Master of Pharmacy in Pharmaceutics

““FFOORRMMUULLAATTIIOONN,, CCHHAARRAACCTTEERRIIZZAATTIIOONN AANNDD EEVVAALLUUAATTIIOONN OOFF

M

I

MAATTRRIIXX TTYYPPEE TTRRAANNSSDDEERRMMAALL PPAATTCCHHEESS OOFF CCAARRVVEEDDIILLOOLL””

By MMrr.. KKAAIILLAASSHH VVIISSHHVVAANNAATTHHRRAAOO VVIILLEEGGAAVVEE

B. Pharm.

Dissertation Submitted to the

Rajiv Gandhi University of Health Sciences, Karnataka, Bangalore

In partial fulfillment of the requirements for the degree of

Master of Pharmacy

in

Pharmaceutics Under the guidance of

Shri. S.P. HIREMATH

M. Pharm, Associate Professor

Department of Pharmaceutics, K.L.E.S’s College of Pharmacy,

Hubli -580031, Karnataka, India.

February 2010

RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,

KARNATAKA, BANGALORE.

DECLARATION BY THE CANDIDATE

I hereby declare that this dissertation entitled “

“FFOORRMMUULLAATTIIOONN,,

C

CHHAARRAACCTTEERRIIZZAATTIIOONN AANNDD EEVVAALLUUAATTIIOONN OOFF MMAATTRRIIXX TTYYPPEE

T

TRRAANNSSDDEERRMMAALL PPAATTCCHHEESS OOFF CCAARRVVEEDDIILLOOLL”” is a bonafide and genuine

research work carried out by me under the guidance of S

Shhrrii.. SS..PP.. HHiirreemmaatthh.

Associate Professor, Department of Pharmaceutics, K.L.E.S’s College of

Pharmacy, Hubli.

Date:

Place: Hubli M

Mrr.. KKAAIILLAASSHH VV..VVIILLEEGGAAVVEE

II



CERTIFICATE BY THE GUIDE

This is to certify that the dissertation entitled ““FFOORRMMUULLAATTIIOONN,,

C CHHAARRAACCTTEERRIIZZAATTIIOONN AANNDD EEVVAALLUUAATTIIOONN OOFF MMAATTRRIIXX TTYYPPEE

T TRRAANNSSDDEERRMMAALL PPAATTCCHHEESS OOFF CCAARRVVEEDDIILLOOLL”” is a bonafide research

work done by M Mrr.. KKaaiillaasshh VViilleeggaavvee in partial fulfillment of the

requirement for the degree of MASTER OF PHARMACY IN

PHARMACEUTICS.

S Shhrrii.. SS..PP.. HHiirreemmaatthh M.Pharm, Associate Professor

Department of Pharmaceutics, Date: K.L.E.S’s College of Pharmacy, Place: Hubli Hubli- 580031.

Karnataka. (India)

III



ENDORSEMENT BY THE HOD, PRINCIPAL/ HEAD OF THE

INSTITUTION

This is to certify that the dissertation entitled “FORMULATION,

CHARACTERIZATION AND EVALUATION OF MATRIX TYPE

TRANSDERMAL PATCHES OF CARVEDILOL” is a bonafide research work

done by M

Mrr.. KKAAIILLAASSHH VVIISSHHVVAANNAATTHHRRAAOO VVIILLEEGGAAVVEE under the

guidance of Shri. S. P. HIREMATH Associate Professor, Department of

Pharmaceutics, K.L.E.S’s College of Pharmacy, Hubli.

Shri. V.G. Jamakandi Dr. B. M. Patil M.Pharm, M.Pharm, PhD.

Professor & Head, Principal & Professor Department of Pharmaceutics, Department of Pharmacology,

K.L.E.S’s College of Pharmacy, K.L.E.S’s College of Pharmacy, Hubli – 580031. Hubli – 580031. Date:

Place: Hubli

IV

COPYRIGHT

Declaration by the Candidate

I hereby declare that the RRaajjiivv GGaannddhhii UUnniivveerrssiittyy ooff HHeeaalltthh

S

Scciieenncceess,, KKaarrnnaattaakkaa,, shall have the rights to preserve, use and

disseminate this dissertation/thesis in print or electronic format for

academic/research purpose.

Date:

Place: Hubli M Mrr.. KKaaiillaasshh VViisshhvvaannaatthhrraaoo VViilleeggaavvee B.Pharm.

© Rajiv Gandhi University of Health Sciences, Karnataka.

V

LIST OF ABBREVIATIONS USED

Abs - Absorbance

AR - Analytical reagent

B.P - British Pharmacoepia

cp - Centipoise

Conc. - Concentration

0C - Degree centigrade

CDR - Cumulative drug release

%CDR - Percentage cumulative drug release

Cm2 - Centimeter square

DBP - Dibutyl phthalate

D.F - Dilution factor

DSC - Differential Scanning Calorimetry

EC - Ethyl cellulose

FTIR - Fourier transform infrared

Fig - Figure

gms - Grams

μgm/µg - Micro gram

HPMC - Hydroxy propyl methyl cellulose (6 cps)

hrs - Hours

ICH - International Conference on Harmonisation

Kp - Permeability coefficient

Kg - Kilo grams

Kg/cm2 - Kilograms per square centimeter

LR - Laboratory reagent

I

λ Max - Absorption maxima

mg - Milligram

min - Minute

MIPB - 30% v/v methanolic isotonic phosphate buffer of pH 7.4

ml - Milliliter

mm - Millimeter

nm - Nanometer

Ph Eur - European Pharmacoepia

RH - Relative humidity

RFCL Ltd. – Ranbaxy Fine Chemicals Limited

rpm - Revolutions per minute

SEM - Scanning electron microscopy

SS-I - Stock solution – I

SS-II - Stock solution – II

S.D. value - Standard deviation value

TEC - Tri ethyl citrate

Temp - Temperature

TDDS - Transdermal drug delivery system

UV - Ultra violet spectroscopy

USP - United States Pharmacopoeia

v/v - Volume/volume

wt. – Weight

w/v - Weight/volume

w/w - Weight/weight.

XRD - X-Ray Diffractometer

II

TABLE OF CONTENT

Serial No.

Contents

Page No.

1 Introduction 1

2 Objectives 33

3 Review of literature 38

4 Materials and Methodology 58

5 Results 84

6 Discussion 158

7 Conclusion 170

8 Summary 171

9 Bibliography 176

10 Annexures 188

III

LIST OF TABLES

SI. No.

TABLES Page No.

1 Characteristics of drug-in-adhesive and matrix patches v/s. reservoir patches

3

2 Pharmacokinetic properties of Carvedilol 40

3 Chemical names of Eudragit RL and RS 100 43

4 List of chemicals used with grade and supplier/manufacturer names 58-59

5 Details of equipments used 60

6 Formulation design for Eudragit combination patches 69

7 Formulation design for HPMC(6 cps):EC patches 69

8 Data for standard Calibration curve of Carvedilol in 30% v/v

Methanolic Isotonic Phosphate Buffer (MIPB) of pH 7.4

85

9 Data obtained from preformulation studies of Carvedilol. 86

10 Data of various Preformulation studies 87

11 Data obtained from in-vitro flux study of Carvedilol through Porcine ear skin

88

12 Optimization of TDDS patches using Eudragit RL and RS 100 as polymers with DBP as plasticizer

91

13 Optimization of TDDS patches using Eudragit RL and RS 100 as polymers with TEC as plasticizer

92

IV

14 Optimization of TDDS patches using HPMC and EC as polymers with DBP & TEC as plasticizers

93

15 Data obtained from skin irritation test for drug free and optimized polymeric patches

94

16 Data obtained from compatibility studies of drug and polymers by FTIR spectroscopy

100

17 Data obtained from compatibility studies of drug and polymer by DSC thermograms

106

18 Summary of data showing physical parameters and drug content of TDDS

112

19 Data obtained from percentage moisture uptake for Eudragit RS : RL 100 patches

113

20 Data obtained from percentage moisture uptake for HPMC : Ethyl cellulose patches

114

21 Data obtained from percentage moisture content for Eudragit RS : RL 100 patches

115

22 Data obtained from percentage moisture content for HPMC : Ethyl cellulose patches

116

23 Data obtained from Tensile strength and Elongation of Eudragit RL: RS 100 patches

117

24 Data obtained from Tensile strength and Elongation of HPMC: EC patches

118

25 Data obtained from water vapor transmission studies for Eudragit RS : RL 100 patches

119

26 Data obtained from water vapour transmission studies for HPMC : Ethyl cellulose patches

121

V

27 Data obtained from Adhesive property of patches by Thumb tack test

128

28 Data obtained from dissolution study of optimized patches using USP paddle method

129

29 In vitro release study of formulation RSL 1 through dialysis membrane

131

30 In vitro release study of formulation RLS 2 through dialysis membrane

132


133


134


135


136


137


138

37 In vitro release study of formulation RHE 1 through dialysis membrane

141


142


143


144

VI


145


146


147

44 In vitro release study of formulation optimized with Eudragit RS : RL 100 (RSL 2) through

Porcine ear skin

149

45 In vitro release study of formulation optimized with HPMC : EC (RHE 3) through

Porcine ear skin

150

46 : In vitro release study of formulation optimized with HPMC : EC (RHE 3) through

Porcine ear skin

152

47 Kinetic data of various models applied to release study of best formulations

154

48 Data obtained from stability studies for physico-chemical parameters of optimized patches

155

VII

LIST OF FIGURES

SI. No.

FIGURES Page No.

1 Simplified structure of skin 5

2 Transport pathways of drugs through stratum corneum 9

3 A) Process of percutaneous absorption & transdermal delivery

10

4 B) Dermal absorption, sites of action & toxicity 10

5 Polymer membrane permeation controlled TDDS 16

6 Polymer Matrix Diffusion-Controlled TDDS 17

7 Drug Reservoir Gradient-Controlled TDD System 18

8 Microreservoir Dissolution Controlled TDDS 19

9 Release Liner 21

10 Backing Layer 22

11 Shimadzu, DSC Q20 V24.4, Japan. DSC Instrument 67

12 Universal Strength Testing Machine 72

13 JEOL, JSM-6360A, Japan Scanning Electron Microscope. 74

14 Stability Chamber 75

15 Magnetic Stirrer with Franz Diffussion cell 78

VIII

16 Albino Wistar rats prepared for in vivo study 80

17 Biopack Machine

81

18 Photographs of Eudragit RS: RL 100 patches 123

19 Photographs of HPMC: Ethyl cellulose patches 124

20 Scanning Electron Microscopy of formulation RSL 2 125

21 SEM photograph of the transdermal film (RSL2) showing the patch behaviour after the release of drug

126

22 Scanning Electron Microscopy of formulation RHE 3 127

IX

LIST OF GRAPHS

SI. No. GRAPHS Page No.

1 Standard Calibration curve of Carvedilol 85

2 Flux of Carvedilol through porcine ear skin 89

3 Water vapour transmission profile for Eudragit RL: RS 100 patches

120

4 Water vapor transmission profile for HPMC : EC patches 122

5 Dissolution profile for Eudragit RL:RS 100 and HPMC patches 130

6A In vitro release profile for Eudragit formulations through dialysis membrane

139

6B In vitro release profile for Eudragit formulations through dialysis membrane

140

7 In vitro release profile for HPMC : EC formulations through dialysis membrane

148

8 In vitro permeation profile for optimized formulations RLS 1 and RHE 4 through porcine ear skin.

151

X

LIST OF SPECTRA

SI. No. SPECTRA Page No.

1 UV spectra of Carvedilol 84

2 FTIR spectra of Carvedilol 94

3 FTIR spectra of Eudragit RL and RS 100 96

4 FTIR spectra of Eudragit RL 100, RS 100 and Carvedilol 97

5 FTIR spectra of HPMC (6 cps) and EC 98

6 FTIR spectra of HPMC (6 cps), EC and Carvedilol 99

7 DSC thermogram of Carvedilol 101

8 DSC thermogram of Eudragit RL and RS 100 102

9 DSC thermogram of Carvedilol, Eudragit RL and RS 100 103

10 DSC thermogram of HPMC (6 cps) and EC 104

11 DSC thermogram of Carvedilol, HPMC (6 cps) and EC 105

12 XRD spectra of Carvedilol 107

13 XRD spectra of Eudragit RL100:RS100 and Carvedilol Transdermal patch

108

14 XRD spectra of HPMC: EC and Carvedilol Transdermal patch 109

15 XRD spectra of Eudragit RL100:RS100 Blank Transdermal patch

110

16 XRD spectra of HPMC: EC Blank Transdermal patch 111

17 Stability studies: FTIR spectra of formulation RLS 2 156

18 Stability studies: FTIR spectra of formulation RHE 3 157

XI

ABSTRACT

The present study was carried out to formulate, characterize and evaluate a matrix-type transdermal

formulation containing carvedilol with different ratios of hydrophilic (Eudragit RL100,HPMC) and

hydrophobic polymeric (Eudragit RS100,Ethyl Cellulose) combinations plasticized with triethyl Citrate and

dibutyl pthalate by the solvent evaporation technique.

The interference of the polymers were ruled out by infrared spectroscopy, DSC and XRD and

accelerated stability studies as per ICH guidelines. In-vitro release study was performed using Keshary-

Chein diffusion cell with Himedia dialysis membrane and porcine ear skin as barriers.

The partition coefficient was determined using n-octanol-water system. The prepared patches were

tested for their physicochemical characteristics such as thickness, weight and drug content uniformity, water

vapour transmission, folding endurance, and tensile strength. In vitro release studies of carvedilol-loaded

patches in 30% v/v Methanolic Isotonic Phosphate Buffer(MIPB) of pH 7.4 exhibited drug release in the

range of 63.00 to 94.56 % in 24 h.

Based on the physicochemical and in-vitro skin permeation studies, patches coded as RSL2 (Eudragit

RS100: Eudragit RL100, 2:8) and RHE 3 (HPMC: Ethyl Cellulose, 7:3) were chosen for further in-vivo

studies.

Data of in vitro release from patches were fit in to different equations and kinetic models to explain

release kinetics. The models used were zero and first-order equations, Hixon-Crowell, and Higuchi and

Korsmeyer-Peppas models. In-vitro release study showed that formulations with highest proportion of

Eudragit RL 100 gave better release as compared to other Eudragit formulations. In HPMC-Ethyl cellulose

series RHE 3 (7:3) ratio showed faster release as compared to other formulations.

The antihypertensive activity of the patches was studied using methyl prednisolone acetate induced

hypertensive rats. It was observed that In Eudragit combinations the RSL 1 formulation and In case of

HPMC: EC combinations the RHE 3 formulation was most effective in the reduction of systolic BP. The

developed transdermal patches increase the efficacy of Carvedilol for the therapy of hypertension.

Keywords: Carvedilol; transdermal; Eudragit RS 100, Eudragit RL 100, HPMC, EC; in vitro permeation.

In vivo studies

Chapter 1 Introduction

1.0 INTRODUCTION

Transdermal drug delivery systems are devices containing drug of defined

surface area that delivers a pre-determined amount of drug to the surface of intact skin at

a pre-predefined rate.1 The skin as a route for systemic drug administration has become

very attractive since the introduction of transdermal therapeutic systems in the form of

patches.2 A transdermal patch is a medicated adhesive patch that is placed on the skin to

deliver a time-released dose of medication systemically for treating illnesses. Since early

1980s, this dosage form of transdermal therapeutic system has been available in the

pharmaceutical market.3 The discovery of transdermal drug delivery systems (TDDS) is

a breakthrough in the field of controlled drug delivery systems. The ability of TDDS to

deliver drugs for systemic effect through intact skin while bypassing first pass

metabolism has accelerated transdermal drug delivery research in the field of

pharmaceutics. Over a decade of such extensive research activities, many transdermal

patches have been developed and successfully commercialized.4

Preparation of TDDS consists of three basic designs: membrane control or

reservoir patches (RPs), matrix or monolithic patches (MPs), and Drug in adhesive

patches (DIAPs).5

The earliest TDDS were reservoir-type devices that used membranes to control

the rate of drug release.6 Reservoir patches contain the drug in a raised compartment,

diffusing it through a polymeric membrane that controls the release rate, usually

providing true zero-order kinetics. Matrix patches combine the drug, polymeric

membrane, and adhesive into a single layer, the polymeric matrix. Drug is diffused

through the polymeric matrix and through the skin. The drug closest to the skin is

Dept. of pharmaceutics, KLES’s COP, Hubli 1


released first, and drug deeper within the patch travels a longer diffusional path before

being released. This pattern departs slightly from zero-order kinetics, but the difference is

generally not clinically significant. Matrix patches are smaller and thinner than reservoir

patches, features that have increased patch acceptability among patients.7

Monolithic matrix systems consist of a polymeric material in which the drug is

dispersed or dissolved, acting simultaneously as a combined drug reservoir and skin

contact adhesive layer.8 Today a drug is more commonly dispersed or dissolved in a

pressure-sensitive adhesive (PSA) matrix also called as drug in adhesive patches.6

In the simplest form, the adhesive matrix or drug-in-adhesive (DIA) design, the

drug is directly loaded or dispersed into the PSA polymer. The adhesive matrix provides

several functions, including skin adhesion, storage of the drug, and control over

drug/enhancer delivery rate, and it also governs their partitioning into the stratum

corneum.9

When the characteristics of these three different patches are compared (Table

1), DIAPs and MPs are clearly superior to RPs in terms of patient compliance. It might

also be expected, because of their simple structure, that DIAPs and MPs are superior

from the commercial viewpoint in terms of the manufacturing process control, quality

control and continuous product improvement. Moreover, the thinner construction of MPs

and DIAPs may improve wearing comfort for the patient. However, drug formulations for

MPs are more challenging to produce, particularly for those patches that incorporate the

drug in the adhesive.5



Table 1. Characteristics of drug-in-adhesive and matrix patches vs. reservoir patches:5

Type Structure Formulation Skin conformability

Size adjustment Dose dumping

Drug in adhesive (DIA) or matrix

patch (MP)

Simple thin layer

Complex Good Easy Low potential

Reservoir Patch (RP)

Complex multi-layer

Simple Some

discomfort

Difficult

Possible breakage of

rate controlling layer.

Several factors should be considered before choosing an appropriate design for a

particular compound: drug solubility, stability and release rate. As a rule of thumb, if a

drug permeates or crosses the skin faster than desired, RPs can slow down or control the

permeation. Alternatively, if a drug passes through skin at a slower rate than the patch

releases it, MPs probably containing a suitable chemical penetration enhancer may

suffice.5

1.1 The Skin site for transdermal drug administration: 10

The skin constitutes one of the largest interfaces between the body and the

environment. On the one hand, the function of human skin is to protect our body against

chemical, physical, and microbial injury, loss of water, and other endogenous substances;

on the other hand, it is involved in the thermoregulation of the body and serves as an

excretory organ. This bifunctional nature of the skin depends on its highly differentiated

structure, with the main barrier function being located in the outermost skin layer, the

stratum corneum.

The skin is one of the most extensive and readily accessible organs of the

human body. The skin of an average adult body covers a surface area of approximately



2m2 (or 3000 inch2) and receives about one third of the blood circulating through the

body.

1.2 Anatomical structure of human skin:10 (Figure 1)

The multitude of different functions of the human skin can only be achieved by

a unique anatomical structure of the different skin layers. These are as follows:

A ) Epidermis consisting of:

-- Stratum corneum (outermost layer)

-- Viable epidermis

B) Dermis

C) Subcutis or subcutaneous fatty tissue

1.2.1 Epidermis:

Because of practical reasons, the human epidermis can be generally divided into

two main layers, the stratum corneum and the viable epidermis. The stratum corneum

consists of separated nonviable cornified almost nonpermeable corneocytes embedded

into a continuous lipid bilayer made of various classes of lipids, for example, ceramides,

cholesterol, cholesterol esters, free fatty acids, and triglycerides. Structurally, this

epidermis layer is best described by the so-called brick-and-mortar model.

The stratum corneum is crucial for the barrier function of the skin, controlling

percutaneous absorption of dermally applied substances and regulating fluid homeostasis.

The thickness of the stratum corneum is usually 10–25 μm, with exceptions at the soles of

the feet and the palms, which swells several-fold when hydrated. All components of the



stratum corneum originate from the basal layer of the epidermis, the stratum

germinativum.

Fig. no.1: Simplified structure of Skin

The viable epidermis is made of several layers starting with the innermost

layer called stratum germinativum (the basal layer), followed by the stratum spinosum,

the stratum granulosum, and the stratum lucidum, which is present only at the palm of the

hand and at the sole of the foot. Over the course of 28 days cells originating from the

stratum germinativium migrate to the skin surface undergoing various states of

differentiation. The cells in doing so lose their nuclei, get flattened, discharge lipids into

the intercellular space (stratum granulosum) and are cornified building up the unique

stratum corneum structure.



1.2.2 Dermis:

Depending on the body site, the thickness of the dermis ranges from 3 to 5 mm.

The dermis consists of a matrix of connective tissue composed of collagen, elastin, and

reticulin and is interspersed by skin appendages such as sweat glands, pilosebaceous units

and hair follicles. Furthermore nerves, lymphatic and blood vessels are located in this

skin layer. Blood vessels are found directly beneath the stratum germinativum of the

viable epidermis supplying nutrients and removing metabolites.

For systemic drug absorption, both the blood system and the lymphatic system

are responsible, acting as sinks and hence keeping the drug concentration in the dermis

low.

1.2.3 Subcutis or subcutaneous fatty tissue:

The subcutaneous fatty layer acts mainly as a heat insulator and a mechanical

cushion and stores readily available high-energy chemicals.

1.3 Skin appendages:10

Skin appendages can be distinguished into hair follicles with their associated

sebaceous glands, eccrine sweat glands, apocrine sweat glands, and nails.

1.3.1 Hair follicles:

Hair follicles with their associated sebaceous glands are present all over the skin

surface with the exception of lips, palms, and soles. Furthermore, hair follicles intersperse

down to the subcutis offering permeation pathways deep into the skin. The density of hair

follicles varies with species and body site. The sebaceous glands produce the sebum,

which lubricates and protects the skin and is involved in the regulation of the pH on the

skin surface.



1.3.2 Sweat glands:

Sweat glands also called as eccrine glands. Sweat glands can be found on the

entire body surface of humans except for the lips, external ear canal, clitoris, and labia

minora. These glands play an important role in thermoregulation which is necessary for

fluid and electrolyte homeostasis. They secrete a milky or oily odorless liquid which

produces the characteristic body smell after metabolism through surface bacteria of the

skin.

1.4 Drug transport through human skin: 5,11

Human skin is an effective, selective barrier to chemical permeation. Most small

water-soluble non-electrolytes diffuse into the systemic circulation a thousand times more

rapidly when the horny layer is absent.

Among the various skin layers, stratum corneum (SC) is the rate-limiting barrier

to percutaneous drug transport due to its desquamating 'horny' properties comprising

about 15–20 rows of flat partially desiccated dead keratinized epidermal cells. Due to the

lipid - rich nature of the SC layer (40% lipids, 40% protein and only 20% water) and its

low water content transport of hydrophilic or charged molecules across SC is low while

transport of lipophilic drug molecules such as fentanyl is higher due to their lipid

miscibility with intercellular lipids around the cells in the SC layer.

1.5 Skin absorption pathways: 10

Skin absorption pathways can be divided into the transport:

(1) Across the intact stratum corneum and



(2) Along the skin appendages.

The physicochemical properties of the drug as well as the nature of the formulation are

the main factors influencing the choice of pathway.

1.5.1 Transport across the intact stratum corneum: (Figure 2 and 3)

Originating from the structure of the stratum corneum two permeation pathways

are possible:

(a) The intercellular route and

(b) The transcellular route.

The intercellular route is considered to be the predominantly used pathway in

most cases especially when steady-state conditions in the stratum corneum are reached.

Substance transport occurs in the bilayer-structured continuous intercellular lipid domain

within the stratum corneum. Although this pathway is very tortuous and therefore much

longer in distance than the overall thickness of the stratum corneum (~20 µm) and has

been estimated as long as 500 µm. The intercellular route is considered to yield much

faster absorption due to the high diffusion coefficient of most drugs within the lipid

bilayer. Resulting from the bilayer structure, the intercellular pathway provides

hydrophilic and lipophilic regions allowing more hydrophilic substances to use the

hydrophilic and more lipophilic substances to use the lipophilic route.

Under normal conditions the transcellular route is not considered as the

preferred way of dermal invasion the reason being the very low permeability through the

corneocytes and the obligation to partition several times from the more hydrophilic

corneocytes into the lipid intercellular layers in the stratum corneum and vice versa. The



transcellular pathway can gain an importance when a penetration enhancer is used, for

example, urea which increases the permeability of the corneocytes by altering the keratin

structure.

Fig 2: Transport of drugs through stratum corneum

1.5.2 The appendages route:

The appendages route consists of the glandular and the follicular pathways with

the latter one being the more important. However, since appendages cover only 0.1% of

the whole skin surface area these pathways do not contribute significantly to dermal

absorption during steady-state conditions of skin absorption. In contrast, in the initial

stages of a skin absorption process and in the case of large hydrophilic compounds and

ions invasion through the appendages may play a considerable role. Recent studies also

report that the appendages route may be involved in the absorption of liposomes,

nanoparticles, and cyclodextrin-inclusion complexes.



Fig. No: 3 (A) Structure of the skin and processes of percutaneous absorption and

transdermal delivery. Absorption can occur through sweat ducts (1), intercellular regions

of the stratum corneum (2) and through the hair follicles (3).

Fig. No: 4 (B) Dermal absorption, sites of action and toxicity12.



1.6 Physicochemical parameters important in dermal absorption:13

The most basic diffusion equation is Fick’s 1st law which describes steady state

flux per unit area (J) in terms of the partition of the permeant between the skin and the

applied formulation (K), its diffusion coefficient (D) in the intercellular channels of

diffusional path length (h), the applied concentration of the permeant in the vehicle (Capp)

and the concentration of the permeant in the receptor phase (Crec):

J = KD (Capp – Crec)/h ----------------- (1)

In most circumstances Crec <<Capp and Eq. (1) is often simplified to:

J = kp Capp ----------------- (2)

Where kp (= KD/h) is the permeability coefficient. This parameter (from an aqueous

donor phase) may be estimated by an empirical relationship described by Potts and Guy:

Log [kp/ (cm h-1)] = -2.7 + 0.71 log Koct – 0.0061 MW ----------------- (3)

Where Koct is the octanol water partition coefficient and MW is molecular weight.

The maximum flux for a compound is when Capp is equal to the solubility.

Simple inspection of the equation shows that the important physicochemical properties

are partition coefficient, diffusion coefficient, and solubility. Large molecules will

tend to diffuse slowly, hence the MW term in Eq. (3), molecules with good solubility in

both oils and water will permeate well. These tend to be compounds with low melting

point. Eq. (1) or (3) would tend to indicate that a high partition coefficient will favour a

high flux however, large values of K tend to produce molecules that have poor solubility

and in general molecules with a log Koct ~ 1 – 3 have the optimum partition behaviour.

This also fits with the notion stated nearly half a century ago that, a balanced solubility in

both oils and water is desirable.



1.7 The potential advantages of transdermal rate-controlled therapy include the

following: 15, 16

• Improved bioavailability for many drugs.

• Reliable blood levels of drug.

• Sustained therapeutic effect, allowing use of drugs with short half-lives.

• Diminished side effects.

• Improving patient compliance in long term therapy.

• Simple, noninvasive administration particularly important for patients who

are unable to take medication orally.

• Reduced overall treatment costs in many instances.

• Minimizing inter- and intra-patient variability.

• Making it possible to interrupt or terminate treatment when necessary.

These advantages of transdermal therapy may yield enhanced safety,

efficacy, reliability and acceptability of drug treatment.

1.8 Limitations of transdermal delivery:3,15,17

• As with the other routes of drug delivery, transport across the skin is also

associated with several disadvantages, the main drawback being that not

all compounds are suitable candidates.

• A number of physicochemical parameters have been identified that

influence the diffusion process and variations in permeation rates can

occur between individuals, different races and between the old and young.



• Furthermore, diseased skin, as well as the extent of the disease can also

affect permeation rates.

• The metabolic enzymes in the skin can also pose a problem and some

drugs are almost completely metabolized before they reach the cutaneous

vasculature.

• Another problem that can arise which is sometimes overlooked is that,

some drugs can be broken down before penetration through the SC by the

bacteria that live on the skin surface.

One of the major limitations of TDDS is that sometimes it may induce an

irritation or sensitization reaction of the skin.

1.9 Factors affecting transdermal permeability:14

The factors controlling transdermal permeability can be broadly placed in the

following cases:

I. Physico-chemical properties of the penetrant molecules:

1. Partition coefficient: Drugs having both lipid and water solubilities are favorably

absorbed through skin. Transdermal permeability coefficient shows a linear

dependency on partition coefficient. A lipid /water partition coefficient of one or

greater is generally required.

2. pH conditions: The pH value of high or low can be destructive to the skin. With

moderate pH values, the flux of ionisable drugs can be affected by changes in pH that

alter the ratio of charged to uncharged species and their transdermal permeability.



3. Penetrant concentration: Increasing concentration of dissolved drug causes a

proportional increase in flux. At higher concentration excess solid drug function as

reservoir and help to maintain a constant drug concentration for a prolonged period of

time.

II. Physico-chemical properties of drug delivery systems:

1. Release Characteristic: Solubility of the drug in the vehicle determines the release

rate. The mechanism of drug release depend on the following factors:

a) Whether the drug molecules are dissolved or suspended in the delivery system.

b) The interfacial partition coefficient of the drug from the delivery system to skin.

c) pH of the vehicle.

2. Enhancement of transdermal permeation: Majority of drugs will not penetrate the

skin at rates sufficiently high for therapeutic efficacy. The permeation can be

improved by the addition of permeation enhancer into the system.

III. Physiological and pathological condition of skin:

1. Reservoir effect of horny layer: The horny layer especially is deeper layer can

sometimes act as a depot & modify the transdermal permeation of drugs. This effect is

due to irreversible binding of a part of the applied drug with the skin.

2. Lipid film: The lipid film on the skin surface acts as a protective layer to prevent the

removal of moisture from the skin and helps in maintaining the barrier function of

stratum corneum.



3. Skin hydration: Hydration of stratum corneum can enhance permeability. Skin

hydration can be achieved simply by covering or occluding the skin with plastic

sheeting, leading to accumulation of sweat. Increased hydration appears to open up the

dense closely packed cells of the skin and increases its porosity.

4. Skin temperature: Raising the skin temperature results in an increase in the rate of

skin permeation; this may be due to availability of thermal energy required for

diffusivity.

5. Regional variation: Differences in nature and thickness of the barrier layer of skin

causes variation in permeability.

6. Pathological injuries to the skin: Injuries that disrupt the continuity of the stratum

corneum increases permeability due to increased vasodilatation caused by removal of

the barrier layer.

7. Cutaneous self metabolism: Catabolic enzymes present in the epidermis may render

the drug inactive by metabolism and the topical bioavailability of the drug is greatly

reduced.

1.10 Transdermal drug delivery system designs:9

Transdermal drug delivery can be achieved via active or passive systems

depending on whether external energy is used to assist the transport of the drug through

the skin. The active systems use heat, electric current (iontophoresis), sound waves

(sonophoresis), or transient high-voltage electrical pulses (electroporation) to enhance the

delivery of drugs into the systemic circulation.

In passive transdermal drug delivery systems, the drug diffuses through the skin

into the systemic circulation by passive means. The concentration gradient of the drug



across the skin and the difference in solubility between the adhesive and skin are the

driving force for delivery to the surface of the skin. In general, chemical permeation

enhancers (pharmaceutical excipients) are required for passive delivery to achieve the

required delivery of the drug from a patch of a reasonable size (that is, a surface area of ≤

40 cm2).There are four major designs of the conventional passive transdermal drug

delivery patches.

1.11 Different technologies employed in the development of TDDS:14

I. Polymer Membrane Permeation controlled TDDS:

Fig No 5: Cross section view of polymer membrane permeation controlled TDDS

In this system the drug reservoir is sandwiched between a drug-impermeable

backing laminate and a rate-controlling polymeric membrane. The drug molecules are

permitted to release only through the rate-controlling polymeric membrane. In the drug

reservoir compartment the drug solids are dispersed homogeneously in a solid polymer

matrix (e.g., polyisobutylene), suspended in an unleachable, viscous liquid medium e.g.,

silicone fluid) to form a pastelike suspension, or dissolved in a releasable solvent (e.g.,

alkyl alcohol) to form a clear drug solution. On the external surface of the polymeric



membrane a thin layer of drug-compatible, hypoallergenic pressure-sensitive adhesive

polymer, e.g., silicone adhesive, may be applied to provide intimate contact of the TDD

system with the skin surface. The intrinsic rate of drug release from this type of TDD

system is defined by:

dt =

Km/r Ka/m Da Dm

Km/r Dm ha + Ka/m Da hmCR (4) dQ

Where: CR ― Drug concentration in the reservoir compartment.

Km/r & Ka/m ― Are the partition coefficients for the interfacial partitioning of

drug from the reservoir to the membrane and from the membrane

to the adhesive.

Dm & Da ― Are the diffusion coefficients in the rate-controlling membrane

and in the adhesive layer.

hm & ha ― Are the thickness of rate controlling membrane and adhesive layer.

II. Polymer Matrix Diffusion-Controlled TDDS :

Fig No 6: Cross section view of polymer Matrix Diffusion-Controlled TDDS.



In this approach the drug reservoir is formed by homogeneously dispersing the

drug solid in a hydrophilic or lipophilic polymer matrix and the medicated polymer

formed is then molded into medicated disks with a defined surface area and controlled

thickness. This drug reservoir-containing polymer disk is then mounted onto an occlusive

baseplate in a compartment fabricated from a drug-impermeable plastic backing. In this

system the adhesive polymer is applied along the circumference of the patch to form a

strip of adhesive rim surrounding the medicated disk. The rate of drug release from this

polymer matrix drug dispersion-type TDD system is given by:

dQ dt

= Ld Cp Dp

2t

1/2

(5)

Where: Ld ― Drug loading dose initially dispersed in the polymer matrix.

Cp & Dp ― Solubility and diffusivity of the drug in the polymer matrix.

t ― Time.

III. Drug Reservoir Gradient-Controlled TDD System:

Fig No 7: Cross section view of Drug Reservoir Gradient-Controlled TDDS



The polymer matrix drug dispersion-type TDD system can be modified to have the

drug loading level varied in an incremental manner, forming a gradient of drug reservoir

along the diffusional path across the multilaminate adhesive layers. The rate of drug

release from this type of drug reservoir gradient-controlled TDD system can be expressed

by:

dQ dt

= Ka/r Da

ha (t) Ld (ha) (6)

In this system the thickness of diffusional path through which drug molecules

diffuse increase with time, i.e., ha(t). To compensate for this time-dependent increase in

diffusional path as a result of drug depletion due to release, the drug loading level in the

multilaminate adhesive layers is also designed to increase proportionally, i.e., Ld(ha).

This, in theory should yield a more constant drug release profile.

IV. Microreservoir Dissolution Controlled TDD system

Fig No 8: Cross section view of Microreservoir Dissolution Controlled TDDS



This type of drug delivery system can be considered a hybrid of the reservoir

and matrix dispersion-type drug delivery systems. In this approach the drug reservoir is

formed by first suspending the drug solids in an aqueous solution of a water-miscible

drug solubilizer, e.g., polyethylene glycol and then homogeneously dispersing the drug

suspension with controlled aqueous solubility in a lipophilic polymer by high shear

mechanical force to form thousands of unleachable microscopic drug reservoirs. This

thermodynamically unstable dispersion is quickly stabilized by immediately cross-linking

the polymer chains in situ, which produces a medicated polymer disk with a constant

surface area and a fixed thickness. The rate of drug release from a microreservoir drug

delivery system is defined by:

Where:

A = a/b, a is the ratio of the drug concentration in the bulk of elution solution

over the drug solubility in the same medium, and b is the ratio of the drug

concentration at the outer edge of the polymer coating membrane over the

drug solubility in the same polymer composition.

B — is the ratio of the drug concentration at the inner edge of the interfacial

barrier over the drug solubility in the polymer matrix.



Kl, Km & Kp ―are the partition coefficients for the interfacial partitioning of

drug from the liquid compartment to the polymer matrix, from the

polymer matrix to the polymer coating membrane, and from the

polymer coating membrane to the elution solution (or skin).

Dl , Dp & Ds ―are the drug diffusivities in the liquid compartment, polymer

coating membrane, and elution solution (or skin), respectively.

Sl & Sp ― are the solubilities of the drug in the liquid compartment and in the

polymer matrix, respectively and

hl, hp & hd ―are the thickness of the liquid layer surrounding the drug

particles, the polymer coating membrane around the polymer

matrix, and the hydrodynamic diffusion layer surrounding the

polymer coating membrane, respectively.

1.12 Anatomy of Transdermal drug delivery systems:

І. Additives:

1. Release Liner:7

Important properties for the release liner, the system component that is

removed before application to the skin, include easy removability and excipient

resistance. Fig 9



To maintain potency and predictable delivery characteristics, the liner must be

resistant to drugs within the preparation and to humidity.

2. Backing Layer:7,18

Backings are chosen for appearance, flexibility and need for occlusion.

Examples of backings are polyester film, polyethylene film and polyolefin film. Backing

Layer is visible after the system is applied; Fig 10

The backing layer should exhibit excipient resistance, a low moisture vapor

transmission rate and nontoxic composition. Non-excipient-resistant backings may allow

leaching of additives from the backing and alteration of the drug. A low moisture vapor

transmission rate is essential to retain skin moisture and hydrating the area 0here by

increases drug penetration.

3. Adhesive Layer:9,7

Adhesives are used to maintain intimate contact between the patch and the skin

surface. Many classes of adhesives are available that might be considered for use with

TDDS, although in practice pressure sensitive adhesives (PSAs) are preferred. Pressure

sensitive adhesives are generally defined as materials that adhere to a substrate with light

pressure and which leave no residual adhesive upon their removal and offer the following

advantages:



Convenience of use (PSAs do not require water/solvents or heat in order to

achieve adhesion)

Good stability (PSAs are generally not sensitive to environmental humidity or

temperature degradation)

Simplicity of manufacture

Good appearance.

Three types of PSAs are commonly used in TDD devices: polyisobutylenes (PIBs),

polysiloxanes (silicones) and polyacrylate copolymers (acrylics). Natural rubber / karaya

gum-based adhesives are another class of PSAs used in many over the counter (OTC)

dermal therapeutic systems.

Adhesives in transdermal drug delivery systems must be effective for 1 to 7

days, allow reasonably atraumatic removal, leave the skin, residue free after removal and

worn comfortably without any local, mechanical, chemical or allergic reactions.

4. Overlay:16

A TDDS may include a drug free adhesive coated film, foam or nonwoven

component

designed to be placed over a transdermal patch that has been applied onto the skin. This

overlay secures the medicated patch to the skin of the patient.

5. Membrane:18

A membrane may be sealed to the backing to form a pocket to enclose the drug

contain-ing matrix or used as a single layer in the patch construction. The diffusion

properties of the membrane are used to control availability of the drug and/or excipients

to the skin.



6. Chemical Permeation Enhancers:16,19,21

The skin’s physical structure provides a barrier that may limit the permeation

of some agents. Skin permeation enhancers broaden the range of drugs that can be

delivered transdermally by increasing the penetration of permeants through enhanced

diffusion of the stratum corneum and/or by increasing the solubility of the penetrant.

Protein denaturation may disrupt the barrier as may fluidization and randomization of

intercellular lipids or intercellular delamination and expansion.

Ideally, a permeation enhancer functions only to reduce the barrier resistance

of the stratum corneum and does not damage any viable cells. The ideal enhancer is:

Pharmacologically inert

Nontoxic

Nonirritating

Nonallergenic

Rapid-acting with a duration of activity that is predictable and suited to its use

Chemically compatible and easily formulated into a variety of systems

Inexpensive

Odorless

Tasteless

Colorless

The enhancer should not extract endogenous material out of the skin but should

spread well on skin and have a suitable skin feel. If the substance is a liquid and is to be

used at high volume fractions, it should be a suitable solvent for drugs.



Due to their systemic and localized toxicity, many effective chemical

permeation enhancers have not been explored yet. Hence natural products have

increasingly been used as enhancers due to their better safety profile. Terpenes are

essential oils, which are used as fragrance, flavourings, and medicines. They have been

found effective penetration enhancers for a number of hydrophilic and lipophilic drugs.

Terpenes are highly lipophilic due to their isoprene (C5H8) units. They are generally

recognized as safe (GRAS) by the FDA. They increase the drug diffusivity in the stratum

corneum for hydrophilic drugs and they enhance partitioning of drug into the stratum

corneum for lipophilic drugs, besides causing increased diffusivity.

П. Selection of Drug:14,15,

Drug should be chosen with great care, various parameters to be considered for

the selection of drug includes:

1) Physicochemical properties of drug

1. Should have molecular weight less than 1000 daltons.

2. Should have affinity for both lipophilic and hydrophilic phase.

3. Should have low melting point.

2) Biological properties of drug.

1. Should be potent with daily dose of few mg.

2. Should have short half life.

3. Drug must not induce cutaneous irritation or allergic response.

4. Drug which degrade in GIT or are inactivated by hepatic first pass effect

are suitable candidates.



5. Tolerance to drug must be developed under near zero order release profile

of transdermal delivery.

6. Drugs which have to be administered for long period of time or which

causes adverse effect to non target tissues can also be formulated.

1.13 Kinetics of Drug Release from TDDS:

1. Kinetics of release from monolithic systems14,22

In monolithic system the drug diffuses through the polymer and then partition

into the skin from the system. Matrix diffusion occurs down the concentration gradient at

a rate that is controlled by diffusion coefficient of drug molecular size of the drug. For

the system, which release the drug by diffusion, were proposed by Higuchi. The steady

state drug release from the matrix according to Higuchi equation is:

Q = Dε

(2A − εCs) Cst τ

1/2

(8)

Where, Q - Amount of drug release per unit area of the matrix exposed to the solvent.

A - Total concentration of drug in matrix.

D - Diffusion coefficient of drug in the permeation fluid.

ε - Porosity of the matrix.

τ -Tortousity of the matrix.

Cs - Solubility of drug in dissolution medium.

t - Time.



It was assumed that A was greater that Cs by factor of at least 3 or 4 justifying

the use of this particular equation. Assuming that the diffusion coefficient remain

constant during release, then equation (8) may be reduced to:

Q = K t1/2 (9)

K =

Dε τ

(2A - εCs)Cs (10)

Thus for diffusion controlled mechanism, a plot of percentage of drug release

per unit area of the matrix against square root of time should be linear. The most

important assumption in the theory of Higuchi is that the total surface areas of the matrix

dose not change significantly during diffusion run. Two modes of behavior in such

systems can be expected during diffusion studies,

i. The drug will be released in first mode after an initial swelling of matrix.

ii In another mode, the drug may be diffused out without any swelling or change

of geometry of the matrix.

2. Kinetic Release from membrane controlled systems.14

In membrane controlled system, first the drug will partition from reservoir into

polymer matrix that comprises the rate controlling membrane. In the membrane,

diffusion will occur down a concentration gradient at a rate which will be controlled by

the diffusion coefficient of the drug in the polymer. Once the drug has diffused through



the rate controlling membrane it will partition into skin, diffusion occurs down the

concentration gradient at a rate that is controlled by diffusion coefficient of drug in the

polymer. The rate of permeation dq/dt across various layers of skin tissue can be

expressed as.21

dq dt = Ps (Cd − Cr) (11)

Where,

Cd - Concentration of drug in donor compartment.

Cr - Concentration of drug in receptor compartment.

Ps - Overall permeability coefficient.

Where as Ps can be defined as:

Ps = Ks/d Dss

hs (12)

Where, Ks/d - Partition coefficient.

Dss - Apparent diffusivity.

hs - Thickness of the skin tissues.

Ps can be considered as constant, if Ks/d, Dss and hs terms in above equation are

constant under a given set of conditions. Equation (12) suggest that to achieve a constant

rate of drug permeation, one needs to maintain a condition in which the drug

concentration on the surface of stratum corneum (Cd) is consistently and substantially


(13)


greater than the drug concentration in the receptor side (Cr) i.e., Cd>>Cr under such

condition the above equation is reduced to:

dQ dt

= Ps Cd (13)

By making Cd greater than Cr, the drug concentration on the skin surface is

maintained at level equal to or greater than equilibrium (or saturation) solubility of drug

in stratum corneum Cse i.e., Cd ≥Cs

e then equation (13) can be written as:

dQ dt m

= Ps Cse (14)

1.14 Antihypertention:23,24,25,26

Hypertension is the most common of cardiovascular disease; elevated arterial

pressure causes pathological changes in the vasculature and hypertrophy of the left

ventricle. As a consequence, hypertension is the principal cause of the stroke, leads to

disease of the coronary arteries with myocardial infarction and sudden death, and is a

major contributor to cardiac failure. Hypertension is defined as a conventionally blood

pressure ≥140/90. It should be noted that the risk of both fatal and non-fatal

cardiovascular disease in adults is lowest with systolic blood pressure of less than 120

mm Hg and diastolic is less than 80 mm Hg. These risk increase progressively with

higher levels of both systolic and diastolic blood pressure. Although many of clinical

trials classify the severity of hypertension of diastolic pressure, at every level of diastolic

pressure risks are greater with higher levels of systolic blood pressure.



Hypertension, which is associated with rapidly progressive micro vascular

occlusive disease in the kidney, brain, retina and other organs. The severe endothelial

disruption can lead to microangiopathy hemolytic anemia also untreated malignant

hypertension is rapidly fatal and requires in hospitalization on an emergency basis. Left

ventricular hypertrophy defined by electrocardiogram, or more accurately by

echocardiography is associated with substantially worse long term outcome that includes

the higher risk of sudden cardiac death. The risk of cardiovascular diseases, disability and

death in hypertensive patients also is increased markedly by concomitant cigarette

smoking and by elevated low-density lipoprotein; Effective antihypertensive therapy will

almost completely prevent the hemorrhagic strokes, cardiac failure and renal

insufficiency due to hypertension. As arterial pressure is the product of cardiac output

and peripheral vascular resistance, it can be lowered by action of drugs on either the

peripheral resistance or the cardiac output, or both. Drug may reduce the cardiac output

by either inhibiting myocardial contractility or decreasing ventricular filling pressure

.reduction in ventricular filling pressure may be achieved by action on the venous tone or

on blood volume via renal effects.

Drug can reduce peripheral resistance by acting on a smooth muscle to cause

relaxation of resistance vessels or by interfering with the activity of systems that produce

constriction of resistance vessel.

Several recent clinical trials suggest that reduction of diastolic blood pressure to

85 mm Hg confers a greater therapeutic benefit then reduction to 90 mm Hg, particularly

in patients with diabetes.



The simultaneous use of the drugs with similar mechanism of action and

hemodynamic effect often produce little additional benefit. However concurrent use of

drugs from different classes is a strategy for achieving effective control of blood pressure

while minimizing dose related adverse effects. 25

1. Mechanism for controlling Blood Pressure

Arterial blood pressure is regulated within a narrow range to provide adequate

perfusion of the tissue with out causing damage to the vascular system, particularly the

arterial anemia .Arterial blood pressure is directly proportional to the product of the

cardiac output and the peripheral vascular resistance cardiac output and peripheral

resistance are controlled by two overlapping mechanisms.

A. Baroreceptors and the sympathetic nervous system

B. Renin-angiotensin-aldesterone system 23

It has avoided fluctuations in clonidine blood level and has a lower incidence of

side effects; withdrawal reaction is also less alarming 24

2. Antihypertensive drugs. 24

These drugs used to lower BP in Hypertension.

# Classification of antihypertensive drugs.

1. ACE inhibitors

Captopril,

Enalapril,

Lisinopril,

Ramipril.



2. Angiotensin (AT1) Antagonist.

Losartan,

Candesartan,

Irbesartan.

3. Calcium channel Blockers

Verapamil,

Diltiazem,

Nifidepine,

Amlodipine,

Nitrendipine.

4. Diuretics

Thiazides : Hydrochlorothiazides,

Chlorthalidone,

Indepamide.

High ceiling : Furosemide.

K + Sparing : Sparinolactone,

5. β Adrenergic Blockers: Propranolol.

Atenolol,

Metoprolol.

6. β + α Adrenergic Blockers: Labetolol.

Carvedilol.

7. α Adrenergic Blockers : Prazosin,

Terazocin.

8. Central sympatholytics : Clonidin,

Methyldopa,

9. Vasodilators :

Arteriolars : Hydralazine,

Diazoxide.

Arteriolars + Venous: Sodium Nitropruside.


Chapter 2 Objectives

2.0 OBJECTIVES

2.1 Need for the study: The transdermal route is an alternative for administration of such drugs. This route

improving patient compliance in long term therapy, bypassing first-pass metabolism,

sustaining drug delivery, maintaining a constant and prolonged drug level in plasma,

minimizing inter- and intra patient variability, and making it possible to interrupt or

terminate treatment when necessary. 15

Transdermal drug delivery (TDD) systems are drug-loaded adhesive patches

which, when applied to the skin, deliver the therapeutic agent, at a controlled rate, through

the skin to the systemic circulation and to the target organs.9

Transdermal systems are ideally suited for diseases that demand chronic treatment.

Hypertension, a disease equally prevalent in the developed and the treatment. Under

developed countries, demands chronic An analysis shows that cardiovascular disease (CVD)

was responsible for the highest mortality rate, and mild hypertension may be the humble

beginning for the fatal cardiovascular ailments. Hypertensive patients need to be on

prolonged medication, and sometimes lifelong therapy is advised. Hence noncompliance of

the therapy, especially in cases where dosing frequency is high, is a major problem.

Transdermal delivery is considered to be the ideal method which can bypass the difficulties

of first- pass metabolism, enable absolute elimination of GIT toxic

Dept. of pharmaceutics, KLES’s COP, Hubli

effects, maintain the steady plasma level of drug for a prolonged period and deliver the drug

at predetermined rate without the hazards of specialist care as is required in the intravenous

infusion Since transdermal patches offer a better quality of life, they are more popular than

33


the oral dosage forms Sizeable number of anti hypertensives undergo extensive first-pass

metabolism, the patches used to prevent cardiovascular disorders are

of higher clinical benefit. 27


Since hypertension itself has no symptoms, patients often do not take their

medication. Furthermore, many patients with high blood pressure are treated with several

drugs; as the complexity of the treatment increases, so do the problems of patient

compliance. Patients who take their medications regularly renew their prescriptions more

often than those who do not. For organizations such as Medicaid, which help support the

cost of prescriptions, this means greater expenditures. However, investigation of Medicaid

records shows that although greater patient compliance means more money spent on drugs,

the reductions in complications of hypertension more than compensate for the drug cost.

The net effect of greater patient compliance is a savings of money. In a study of Medicaid

recipients in the state of South Carolina, the costs associated with the use of nine different

antihypertensive drugs were analyzed. Among a total of 8,894 beneficiaries receiving

antihypertensive drugs, the 278 using the transdermal clonidine patch showed significantly

greater patient compliance, as evidence by prescription renewals. The transdermal patch,

which is worn for a week, was associated with better compliance even when used as a part

of a multi-drug regimen. The health care expenditures for patients using the transdermal

patch were significantly less than for those patients who were advised to take

antihypertensive medication more than once a day. There was no significant difference;

however, between patients using the transdermal patch and patients whose antihypertensive

regimen required only one dose per day. The results indicate that simpler drug regimens are

more likely to result in patient compliance. Such regimens result in an overall cost savings

34


for medical care. 29

Carvedilol is the most widely prescribed drug in the long term treatment of

Hypertension. Following oral administration, Carvedilol is rapidly absorbed from the

gastrointestinal tract (80%), but the oral bioavailability remains low (23%) because of

significant first-pass hepatic metabolism by Cytochrome P450 (urinary recovery as

unchanged carvedilol is less than 0.3% of the oral administered dose). Carvedilol also has

a short plasma half-life of 6 hours Long term therapy of hypertension by carvedilol oral

administration may result in poor patient compliance because of low bioavailability and

short plasma half-life, leading to increased frequency of administration. The transdermal

route is an alternative for administration of such drugs. Carvedilol also possesses some

ideal characteristics— such as a low molecular weight (406.5), smaller dose range (25- 50

mg), short plasma half-life, and poor oral bioavailability— for formulation as a transdermal

patch.15

The absorption of drugs through the transdermal route improves bioavailability of

drugs that might otherwise be metabolized by first-pass effect (pre-systemic drug

elimination) during their passage through the gastrointestinal tract. Drug absorption from

the transdermal route is mainly via passive diffusion through the lipoidal membrane. Thus,

transdermal route of drug delivery has attracted the attention worldwide for optimizing the

drug delivery.28


35


2.2 Aim and objectives of the study:

Aim and objective of the present study are to perform “Formulation,

characterization and evaluation of matrix type transdermal patches of Carvedilol ”

This study includes:

• Determination of λ max and preparation of standard calibration curve of

Carvedilol:

1. Preparation of standard solution of Carvedilol.

2. Preparation of working standard solutions

• Preformulation studies:

1. Solubility

2. Partition Coefficient

3. Melting point

4. Permeability of drug through porcine ear skin

5. Formulation of Transdermal patches with different plasticizers.

6. Optimization of patches

7. Permeability Characters of polymers

8. Polymer-skin compatibility

• Compatibility studies of drug and polymers:

1. F.T I.R. Spectroscopy

2. Differential Scanning Calorimetry (DSC).


36


• Formulation design:

A) Preparation of transdermal patches.

B) Evaluation of transdermal formulation:

I. Physico-chemical evaluation

1. Physical appearance

2. Folding endurance

3. Thickness of the film

4. Weight uniformity

5. Drug content

6. Percentage moisture uptake

7. Percentage moisture content

8. Water vapour Transmission

9. Skin irritation test

10. Scanning Electron Microscopy (SEM).

11. X-Ray Diffractometry (XRD)

12.Stability studies according to ICH guidelines.

II. Adhesive test:

1. Thumb tack test

III. In-vitro release study:

1. USP Paddle method

IV. In-vitro membrane permeation study:

1. Keshary-Chien diffusion cell using dialysis membrane.

V. In-vitro skin permeation study:

1. Keshary-Chien diffusion cell using porcine ear skin.

VI. In-vivo study


1. Using Wistar albino rats.

37

Chapter 3 Review of Literature

3.0 REVIEW OF LITERATURE

3.1 Drug profile: Carvedilol: 1,15,22,23,25,26,31,32,35

Description:

Carvedilol is a nonselective β-adrenergic blocking agent with α1-blocking activity,

approval for treatment of Hypertension , symptomatic Heart Failure and Myocardial Infarction.

The ratio of α1 to β receptor antagonist potency for Carvedilol is 1:10.

Structure:

Chemical Formula : C24H26H2O4

Molecular weight : 406.5

Definition : ([3-(9H-carbazol-4-yloxy)-2-hydroxypropyl][2-(2-

methoxyphenoxy)ethyl]amine

Melting range : 1140C to 1160C.

Appearance : White or almost white crystalline powder.

Action and use : Antihypertensive, Antioxidant, Antiproliferative,

And in treating congestive heart failure

Dept. of Pharmaceutics KLES’s COP. Hubli 38


Solubility : Practically insoluble in water, dilute acid. Slightly soluble in

Alcohol, Ethyl Ether. Freely soluble in DMSO. Soluble in Methyl

Chloride, Methanol, Isopropanol,

Storage : Store below 30°C (86°F). Protect from moisture. Dispense in a

tight, light-resistant container

Pharmacokinetics:

Absorption :Carvedilol is rapidly absorbed following oral administration, with peak plasma

concentrations occurring in 1 to 2 hours. It is highly lipophilic and thus is

extensively distributed into extravascular tissues.

Metabolism :Carvedilol is >95% protein bound and is extensively metabolized in the liver

(hepatic), predominantly by CYP2D6 and CYP2C9. The primary P450 enzymes

responsible for the metabolism of both R(+) and S(-)-carvedilol in human Liver

microsomes were CYP2D6 and CYP2C9 and to a lesser extent CYP3A4, 2C19,

1A2, and 2E1. CYP2D6 is thought to be the major enzym in the 4'- and 5'-

hydroxylation of Carvedilol, with a potential contribution from 3A4. CYP2C9 is

thought to be of primary importance in the O-methylation pathway of S(-)-

Carvedilol.

Excretion :About 16% of the drug is excreted via the renal, 60% in Feccal. And < 2% by

urine.



Table 2: Pharmacokinetic properties of Carvedilol

Sl.No Pharmacokinetic parameter Data

1. Daily dose (oral, mg) 25 —50

2. Number of doses per day 2 -- 3

3. Therapeutic concentration range (ng/ml*hr) 105 ± 12

4. tmax (hr) 1 - 2

5. Bioavailability (%) < 30

6. Protein binding (%) > 98

7. Volume of distribution (L) 115

8. Total plasmatic clearance (mL/min) 500 to 700

9. T ½ (hr) 2 to 6

10. Metabolism Hepatic (CYP2D6 and

CYP2C9)

11. Metabolites 7 inactive metabolites

12. Elimination Biliary (60%) --

Urinary (< 2%)

Mechanism of action:

Carvedilol is a racemic mixture in which nonselective beta-adrenoreceptor blocking

activity is present in the S(-) enantiomer and alpha-adrenergic blocking activity is present in

both R(+) and S(-) enantiomers at equal potency. Carvedilol's beta-adrenergic receptor blocking

ability decreases the heart rate, myocardial contractility, and myocardial oxygen demand.

Carvedilol also decreases systemic vascular resistance via its alpha adrenergic receptor blocking



properties. Carvedilol and its metabolite BM-910228 (a less potent beta blocker, but more

potent antioxidant) have been shown to restore the inotropic responsiveness to Ca2+ in OH- free

radical-treated myocardium. Carvedilol and its metabolites also prevent OH- radical-induced

decrease in sarcoplasmic reticulum Ca2+-ATPase activity. Therefore, carvedilol and its

metabolites may be also beneficial in chronic heart failure by preventing free radical damage

Indications and usage:

Left Ventricular Dysfunction Following Myocardial Infarction

Carvedilol is indicated to reduce cardiovascular mortality in clinically stable patients

whohave survived the acute phase of a myocardial infarction and have a left ventricular ejection

fraction of <40% (with or without symptomatic heart failure) .

Hypertension

Carvedilol is indicated for the management of essential hypertension. It can be used

aloneor in combination with other antihypertensive agents, especially thiazide-type diuretics

Dosage and Administration:

Carvedilol should be taken with food to slow the rate of absorption and reduce the

incidence of orthostatic effects.

Left Ventricular Dysfunction Following Myocardial Infarction

Treatment with carvedilol may be started as an inpatient or outpatient and should be

started after the patient is hemodynamically stable and fluid retention has been minimized. It is

recommended that carvedilol be started at 6.25 mg twice daily and increased after 3 to 10 days,



based on tolerability, to 12.5 mg twice daily, then again to the target dose of 25 mg twice daily.

A lower starting dose may be used (3.125 mg twice daily) and/or the rate of up-titration may be

slowed if clinically indicated (e.g., due to low blood pressure or heart rate, or fluid retention).

Patients should be maintained on lower doses if higher doses are not tolerated. The

recommended dosing regimen need not be altered in patients who received treatment with an IV

or oral ß-blocker during the acute phase of the myocardial infarction.

Hypertension

DOSAGE MUST BE INDIVIDUALIZED. The recommended starting dose of

carvedilol is 6.25 mg twice daily. If this dose is tolerated, using standing systolic pressure

measured about 1 hour after dosing as a guide, the dose should be maintained for 7 to 14 days,

and then increased to 12.5 mg twice daily if needed, based on trough blood pressure, again

using standing systolic pressure one hour after dosing as a guide for tolerance. This dose should

also be maintained for 7 to 14 days and can then be adjusted upward to 25 mg twice daily if

tolerated and needed. The full antihypertensive effect of carvedilol is seen within 7 to 14 days.

Total daily dose should not exceed 50 mg. Concomitant administration with a diuretic can be

expected to produce additive effects and exaggerate the orthostatic component of carvedilol

action.

Side effect: The major side effect of Carvedilol is Hypotension.


http://www.rxlist.com/script/main/art.asp?articlekey=3864


3.2 Polymer review34

3.2.1 Polymethacrylates (Eudragit RL and RS 100)

1. Nonproprietary Names:

USPNF: Ammonio methacrylate copolymer

USPNF: Methacrylic acid copolymer

2. Synonyms:

Eudragit; polymeric methacrylates.

Table 3: Chemical name and CAS Registry number

Chemical name Trade name CAS number

Poly(ethyl acrylate, methyl methacrylate,

trimethylammonioethyl methacrylate chloride)

1:2:0.2

Eudragit RL 100 [33434-24-1]

Poly(ethyl acrylate, methyl methacrylate,

trimethylammonioethyl methacrylate chloride)

1:2:0.1

Eudragit RS 100 [33434-24-1]

3. Molecular weight: Molecular weight of the polymer is ≥ 100 000.

4. Functional category: Film-former; tablet binder; tablet diluent.

5. Applications in pharmaceutical formulation or technology:

Polymethacrylates are primarily used in oral capsule and tablet formulations as film

coating agents. Eudragit RL, RS and NE 30 D are used to form water insoluble film coats for



sustained release products. Eudragit RL films are more permeable than those of Eudragit RS,

and by mixing the two types together films of varying permeability can be obtained.

6. Structural formula:

R1 R3 R1 R3

C CH2 C CH2 C CH2 C CH2

C = O C = O C = O C = O

O O O O

R2 R4 R2 R4

For Eudragit RL and RS:

R1 = H, CH3

R2 = CH3, C2H5

R3 = CH3

R4 = CH2CH2N(CH3)3+Cl-

7. Description:

Eudragit RL and Eudragit RS, are copolymers synthesized from acrylic acid &

methacrylic acid esters with Eudragit RL having 10% of functional quarternary ammonium

groups & Eudragit RS having 5% of functional quarternary ammonium groups. Both polymers

are water-insoluble, and films prepared from Eudragit RL are freely permeable to water,

whereas, films prepared from Eudragit RS are only slightly permeable to water.

Solvent-free granules (Eudragit RL & RS 100) contain ≥ 97 % of the dried weight

content of the polymer.



8. Stability and storage condition:

Dry powder polymer forms are stable at temperature less than 300C. Dry powders are stable

for at least two years if stored in a tightly closed container at less than 300C.

3.2.2 Hydroxypropyl methylcellulose (HPMC):

1. Nonproprietary names:

BP: Hypromellose

Ph Eur: Methylhydroxypropylcellulosum

USP: Hydroxypropyl methylcellulose

2. Synonyms:

Cellulose, hydroxypropyl methyl ether; Methocel; Metolose; Pharmacoat; Culminal.

3. Chemical name: Cellulose, 2-Hydroxypropyl methyl ether.

4. Empirical formula:

The PhEur 1992 describes hydroxypropyl methylcellulose as partly O-methylated and O-

(2-hydroxypropylated) cellulose. It is available in several grades which vary in viscosity &

extent of substitution. Grades may be distinguished by appending a number indicative of the

apparent viscosity, in mPa s, of a 2% w/w aqueous solution at 200C.



5. Molecular weight:

Approximately 10 000 – 1 500 000.


Where - R is H, CH3 or [CH3CH(OH)CH2].

7. Functional category:

Coating agent; film-former; stabilizing agent; suspending agent; tablet binder;

viscosity increasing agent.


In oral products, HPMC is primarily used as a tablet binder (in either wet or dry

granulation processes), in film-coating of tablets and as an extended release tablet matrix.

HPMC is also used as a suspending & thickening agent in topical formulations,

particularly ophthalmic preparations. It is also used as an emulsifier, suspending agent &

stabilizing agent in topical gels and ointments.

9. Description:



Hydroxypropyl methylcellulose is an odorless and tasteless, white or creamy-white

coloured fibrous or granular powder.

10. Typical properties:

pH (1% w/w solution): 5.5 — 8.0

Density (tapped): 0.50 — 0.70 g/cm3 for Pharmacoat.

Melting point: Browns at 190-2000C; chars at 225-2300C.

Solubility: Soluble in cold water, forming a viscous colloidal solution;

practically insoluble in chloroform, ethanol (95%) and ether, but

soluble in mixtures of ethanol and dichloromethane and mixtures

of methanol and dichloromethane. Certain grades of HPMC are

soluble in aqueous acetone solutions, mixtures of dichloromethane

& propan-2-ol.

Specific gravity: 1.26

11. Stability and storage conditions:

HPMC powder is a stable material although it is hygroscopic after drying.

HPMC powder should be stored in a well-closed container, in a cool, dry, place.

3.2.3 Ethylcellulose:


BP: Ethylcellulose

PhEur: Ethylcellulosum

2. Synonyms:

Aquacoat; E462; Ethocel; Surelease.



3. Chemical Names and CAS Registry number:

Cellulose ethyl ether [9004-57-3]

4. Empirical formula:

Ethylcellulose is an ethyl ether of cellulose, a long-chain polymer consisting of

anhydroglucose units joined together by acetal linkages.


CH2OC2H5

O

O OC2H5

OC2H5 n

6. Functional category:

Coating agent; tablet binder; viscosity-increasing agent.

7. Description:

Ethylcellulose is a tasteless, free-flowing, white to light tan colored powder.


Ethylcellulose is widely used in oral and topical pharmaceutical formulations.



The main use of ethylcellulose in oral formulations is as a hydrophobic coating agent

for tablets and granules. Ethylcellulose is also widely used in drug microcapsulation. In topical

formulations, ethylcellulose is used as a thickening agent in creams, lotions or gels, provided an

appropriate solvent is used.


Density (bulk): 0.4 g/cm3.

Glass transition temperature: 130 — 1330C.

Solubility: Practically insoluble in glycerin, propylene glycol and water.

Freely soluble in chloroform, methyl acetate, tetrahydrofuran, and in

mixtures of aromatic hydrocarbons with ethanol (95%).

Specific gravity: 1.12 — 1.15.

pH (2% w/w suspension): 5.0 — 7.5

10. Stability and Storage Conditions:

Ethylcellulose is a stable, slightly hygroscopic material. It is chemically resistant to

alkalis, both dilute and concentrated and to salt solutions although it is more sensitive to acidic

materials than cellulose esters.

The bulk material should be stored in a dry place, in a well-closed container at a

temperature between 7-320C.



3.3 Plasticizer review34

3.3.1 Triethyl citrate (TEC)


USPNF: Triethyl citrate

2. Synonyms:

Citric acid, ethyl ester; Citroflex 2; E1505; ethyl citrate; TEC.

3. Chemical name and CAS Registry number:

2-Hydroxy-1,2,3-propanetricarboxylic acid, triethyl ester [77-93-0].

4. Empirical formula: C12H20O7.

5. Molecular weight: 276.29


CH2 COOC2H5

CH2 COOC2H5

C COOC2H5HO

7. Functional category: Plasticizer.

8. Applications in pharmaceutical formulations or technology:



Triethyl citrate and other citrate esters are used as plasticizers for aqueous based

coatings in oral sustained release or enteric coated capsule and tablet formulations. Triethyl

citrate is also used in food products as a sequestrant and in cosmetics as a deodorizing agent.

9. Description:

Triethyl citrate occurs as a bitter tasting, odorless, practically colorless, oily liquid.


Boiling point: 2880C

Flash point : 1550C

Pour point: -450C

Solubility: soluble 1 in 125 of peanut oil, 1 in 15 of water.

Miscible with ethanol (95%) and ether.

Viscosity (dynamic): 35.2 mPa s (35.2 cP) at 250C.

11. Stability and storage conditions:

Triethyl citrate and other citrate esters are stable if stored in a well-closed container in a

cool, dry, place.

3.3.2 Dibutyl phthalate:

1. Synonyms:

1,2-benzenedicarboxylic acid dibutyl ester; n-butyl phthalate; DBP; dibutyl benzene-1,2-

dicarboxylate; di-n-butyl phthalate; Kodaflex DBP; phthalic acid dibutyl ester.

2. Empirical formula: C16H22O4.

3. Molecular weight: 278.35




COOC4H9

COOC4H9

5. Description: DBP occurs as a clear, colorless or faintly colored oily liquid.


Boiling point: 3400C

Density : ~ 1.05 g/cm3

Solubility: Very soluble in acetone, benzene, ethanol (95%), and ether;

soluble 1 in 2500 of water.

Viscosity (dynamic): 15 mPa s (15 cP) at 250C.

7. Applications in pharmaceutical formulations or technology:

DBP is used as a plasticizer in film coatings. It is also used as an insect repellant,

primarily for the impregnation of clothing.

3.4 Review of past work that has been done on Carvedilol and transdermal

patches:

Shashikant D Bharhate et al.,1 Transdermal patches of carvedilol were prepared by using

combination of polyvinyl alcohol (PVP) and polyvinyl pyrrolidone (PVP K30) along with

glycerin,polyethylene glycol 400 and propylene glycol as a plasticizers. The prepared

formulations were evaluated for thickness, drug contentuniformity, folding endurance, percent



elongation at break, tensile strength, in-vitro permeation studies. It was observed that the

system with PVA:PVP in the ratio 8:6 along with used plasticizers was a promising controlled

release transdermal drug delivery system for carvedilol. Formulated transdermal patches of

carvedilol, exhibits zero-order release kinetics.

Sara Nicoli et al.,2 investigated the in vitro kinetics of release and permeation of caffeine from

bioadhesive transdermal films made of polyethylene membrane impregnated with isopropyl

myristate. These films are not self-adhesive but become adhesive when applied to wet skin.

The data obtained in the present work suggest that caffeine release from transdermal

bioadhesive films was controlled either by the permeability characteristics of the skin or by the

film itself, depending on drug loading.

Amir Mehdizadeh et al.,5 evaluated different matrix, drug-in-adhesive (DIA) and reservoir

transdermal formulations of fentanyl with a target of designing a suitable DIA formulation of

fentanyl. Different types & amounts of liquid, pressure-sensitive adhesives (PSAs) were used

and evaluated with respect to drug release and adhesive properties. It was concluded that acrylic

PSAs showed the best adhesion and release properties.

Hock S. Tan et al.,9 reviewed the use of Pressure-sensitive adhesives for transdermal drug

delivery systems (TDDS). Adhesives are a critical component in TDDS. This review discusses

the three most commonly used adhesives (polyisobutylenes, polyacrylates and silicones) in

TDDS and provides an update on recently introduced TDD products and recent developments

of new adhesives.



Ubaidulla U. et al,15 formulated transdermal therapeutic system of carvedilol. And also studied

the effect of hydrophilic and hydrophobic matrix on in vitro and in vivo characteristics. And the

evaluation of physiochemical properties. The carvedilol transdermal patches developed in this

study have grate utility and are a viable option for effective and controlled management

Anna M Wokovich et al.,18 provided an overview on types of transdermal delivery system, their

anatomy, the role of adhesion failure modes and how adhesion can be measured to improve

transdermal adhesive performance.

Adrian C. Williams et al.,19 have discussed a detailed review on Penetration enhancers which

penetrate into skin to reversibly decrease the barrier resistance and improve transdermal

delivery of drugs. Many potential sites and modes of action have been identified for skin

penetration enhancers that are considered in this review.

Naseem Ahmad Charoo et al.,21 investigated the penetration enhancing potential of tulsi and

turpentine oil on transdermal delivery of flurbiprofen. In the present work, the authors have

optimized a flurbiprofen loaded binary solvent mixture composition of propylene glycol :

isopropyl alcohol (30:70%v/v) which is then fabricated into a reservoir type of transdermal

formulation by encapsulating the drug reservoir solution within a shallow compartment,

moulded from polyester backing film & microporous ethyl vinyl acetate membrane. The

prepared patches were subjected to in-vitro drug permeation through rat abdominal skin &

various in-vivo pharmacodynamic studies. In conclusion, the turpentine oil showed superior

absorption enhancing properties on rat skin as compared to the tulsi oil treated, solvent treated

and normal control groups due to increased disruption of stratum corneum with negligible skin

irritation.



Umesh D Shivhare et al.,35 Transdermal films of carvedilol were prepared by using Eudragit

RL100 (ERL100) either alone or in combination with Eudragit RS100 (ERS100),

hydroxypropyl methylcellulose K15LV (HPMC), and ethyl cellulose (EC). The drug release

was extended over a period of 24 h from all formulations. The formulation A5 showed 98.33

cumulative % drug releases in 24 h and followed zero order kinetics. The drug transport

mechanism was observed to be Fickian. The cumulative % drug diffused through artificial

permeation membrane (cellophane A 393) from same formulation was 100.52 % over a 12 h.

The mechanism of dug release was governed by Peppas model and the drug diffusion rate

followed zero order kinetics. The formulation A5 comprising of polymers ERL 100, ERS 100,

EC and HPMC in 7:1:1:1 ratio fulfills the requirement of good TDDS.

Bijaya Ghosh et al.,36 carried out in vitro iontophoretic delivery of glipizide across the pig skin.

The target flux of glipizide was calculated to be 0.4147 µmol h-1. As the highest flux obtained

was 0.2727 µmol cm-2 h-1, the author says that glipizide is a promising candidate for

iontophoretic delivery.

Ubaidulla U. et al,37 has studied the effect of iontophoresis and permeation enhancer on

Carvedilol from Transdermal films. And concluded that the combination of permeation

enhancers and iontophoresis could be useful for increasing the skin permeability of Carvedilol

through the matrix TDDS.

Tashiro Y. et al,38 has studied effect of lipophilicity on in-vivo iontophoretic delivery of β

blockers. In many β -blockers, the relationships between plasma drug concentrations and

pharmacological effects (decreasing heart rate and blood pressure, etc.) has been estimated and



the effect of drug properties on the absorption processes in the iontophoretic transdermal

delivery of beta blocker.

G. D. Gupta et al., 41 prepared matrix type transdermal polymeric membrane systems of

Carvedilol by using eudragit NE 30D as polymer. Various formulations were prepared using

oleic acid, tween-60, span-80 & isopropyl myristate as permeation enhancers at a concentration

of 15% w/w based on polymer weight & subsequently evaluated for in-vitro permeation

enhancing effect by using 30% v/v methanolic isotonic phosphate buffer pH 7.4 as receiver

phase & human cadaver skin as barrier. Different models were applied to evaluate release

mechanism and kinetics. It was found that span-80 showed the best enhancement effect.

Prepared patches were also evaluated for various physico-chemical characteristics.

Srinivas Mutalik et al.,43 prepared reservoir type transdermal systems of glipizide using drug-

containing carbopol gel as drug reservoir and ethyl cellulose as well as Eudragit RS-100,

Eudragit-RL 100 and ethylene vinyl acetate (EVA) as rate-controlling membranes. The

prepared patches were subsequently evaluated for in vitro: drug content and drug permeation

studies and in vivo for: acute and long-term hypoglycaemic activity, effect on glucose tolerance,

biochemical and histopathological studies, skin irritation test and pharmacokinetic studies in

mice. Based on the in vivo study the authors have concluded that a 1 cm2 glipizide transdermal

system prepared with EVA19% membrane showed a cumulative amount of 269.05 µg drug

permeation at the end of 24 h. Hence, a transdermal system of glipizide with an area of

approximately 18 cm2 would be sufficient to provide an optimum effect in humans.

Srinivas Mutalik et al.,44 have prepared glipizide matrix transdermal systems for diabetes

mellitus using the combinations of ethyl cellulose/polyvinylpyrrolidone-K30 (PVP) and



Eudragit RL-100 (ERL)/Eudragit RS-100 (ERS). The systems were evaluated for various in

vitro and in vivo parameters as mentioned in the above article. The in vitro drug release study

through albino mice skin revealed that glipizide release was influenced by PVP and ERL 100

content of the patches. The in vivo results revealed that the patches successfully prevented the

severe hypoglycemia in the initial hours and they were also effective on chronic application.

The present study showed that matrix transdermal patches of glipizide exhibited better in vivo

performance than oral glipizide administration in mice as well reversing the diabetic

complications.

Prakash V. Diwan et al.,45 developed acrylate based transdermal drug delivery system for

glibenclamide by mercury substrate method. Patches were evaluated for its hypoglycemic

activity in normal and streptozotocin induced diabetic rats in comparision with its oral therapy.

In vivo results concluded that, the developed transdermal system is effective in preventing the

frequent hypoglycemic episodes encountered after oral glibenclamide administration in diabetic

rats.

Troy Purvis et al.,46 had produced rapidly dissolving formulations of the poorly water-soluble

drug Carvedilol using an innovative new technology, ultra-rapid freezing (URF), and

investigated the influence of different types and levels of excipients on Carvedilol stability. It

was found that URF process yielded fast-dissolving formulations that were physically &

chemically stable, resistant to alkali.

Ekapol Limpongsa et al.,47 prepared a diltiazem hydrochloride transdermal drug delivery

system by using hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) as hydrophilic

& hydrophobic film formers respectively. Dibutyl phthalate & triethyl citrare were used as



hydrophobic and hydrophilic plasticizers. Effects of HPMC/EC ratios and plasticizers on

mechanical & physical properties of free films were studied. Influence of various enhancers on

in vitro release and permeation through Pig ear skin of diltiazem HCl films were evaluated. It

was found that, the film composed of 8:2 HPMC/EC, 30% DBP and 10% isopropyl myristate,

isopropyl palmitate or Tween 80 loaded with 25% diltiazem HCl should be selected for

manufacturing transdermal patch by using a suitable adhesive layer and backing membrane.


Chapter 4

4.0 METHODOLOGY

The following materials that were either AR/LR grade or the best possible Pharma

grade available were used as supplied by the manufacturer.

MATERIALS USED

Table 4: List of chemicals used with grade and supplier/Manufacturer names

Sl. No. Materials Grade Supplier

1. Carvedilol Pharma

Sun Pharmaceutical Industries,

Mumbai.

Microlabs LTD, Bangalore.

2. Eudragit RL 100 Pharma Evonik Degussa India Pvt. Ltd.,

Mumbai.

3. Eudragit RS 100 Pharma Evonik Degussa India Pvt. Ltd.,

Mumbai.

4. HPMC (6cps) Pharma Arihant Trading Co., Mumbai.

5. Ethyl Cellulose Pharma Deepak Cellulose Pvt. Ltd.,

Mumbai.

6. Tri Ethyl Citrate L.R HiMedia Laboratories Pvt. Ltd.,

Mumbai.

7. Dibutyl phthalate L.R Thomas Baker, Mumbai.

8. Acetone L.R Sd Fine Chem. Ltd., Mumbai.

9. Methanol L.R Sd Fine Chem. Ltd., Mumbai.

10. Methylene Chloride L.R Rankem (RFCL Ltd.), New Delhi.

11. Mercury L.R Sd Fine Chem. Ltd., Mumbai.


Chapter 4

12. Dialysis Membrane HiMedia Laboratories Pvt. Ltd.,

Mumbai.

13. Sodium Chloride L.R Rankem (RFCL Ltd.), New Delhi.

14. Disodium hydrogen

orthophosphate L.R Rankem (RFCL Ltd.), New Delhi.

15. Potassium dihydrogen

phosphate L.R

Qualigens Fine Chemicals (GSK

Pharmaceuticals Ltd.), Mumbai.

16. n-Hexane L.R Sd Fine Chem. Ltd., Mumbai.

17. Formalin Solution L.R Sd Fine Chem. Ltd., Mumbai.

18. Potassium Chloride L.R Rankem (RFCL Ltd.), New Delhi.

19. Calcium Chloride Fused L.R Sd Fine Chem. Ltd., Mumbai.

20 Metyl Prednisolone Acetate Pharma Pfizer India Limited

21. Isopropyl alcohol L.R Rankem (RFCL Ltd.), New Delhi.


Chapter 4

Table 5: Details of Equipments Used

Sl. No.

Instrument Manufacturer

1. Electronic Balance Sartorius, U.K.

2. Digital Screw Gauge Mitutoyo, Japan

3. Hot Air Oven Lawrence & mayo Pvt Ltd., Mumbai

4. Magnetic Stirrers Remi equipments Pvt Ltd., Mumbai

5. Tensile strength & Percentage Elongation testing apparatus

Hounse Field Universal U.K.

6. UV Spectrophotometer Thermo Spectronic, Genesys-6, USA

7. FTIR Spectrophotometer Thermo Nicolet, Japan

8. Dissolution test apparatus (USP XXIII)

ElectroLab, Bangalore

9. Sonicator Enertech electronics Pvt Ltd., Mumbai

10. Digital pH meter Elico India Systronics, Ahmedabad

11. Melting Point apparatus Thermonik, Campbell elctronics. Mumbai

12. DSC Shimadzu, DSC Q20 V24.4, Japan

13 SEM JEOL, JSM-6360A, Japan

14. XRD Philips Analitical XRD PW3710

15. Stability Chamber Thermolab, TH 90 S, Mumbai.

16. Blood Pressure measuring apparatus

Inc Santa Barbara, USA


Chapter 4

Experimental Methods

1. Analytical methods of Carvedilol

1) Determination of λmax of Carvedilol in 30% v/v Methanolic Isotonic Phosphate

Buffer (MIPB) of pH 7.4

2) Calibration curve of Carvedilol in 30% v/v Methanolic Isotonic Phosphate Buffer

(MIPB) of pH 7.4

2. Preformulation Studies

1) Determination of Melting point.

2) Determination of Partition coefficient

3) Permeability studies through porcine ear skin

4) Optimization of transdermal patches with different plasticizers and in

different concentrations.

5) Polymer-Skin compatibility.

6) Determination of drug-excipient compatibility studies

3. Formulation design

4. Evaluation of film

1) Thickness uniformity

2) Weight uniformity

3) Tensile strength

4) Folding endurance

5) Water vapour transmission rate

6) Percentage elongation

7) Drug content uniformity of films

8) In vitro drug release studies

9) In vitro skin permeation studies

10) In vitro skin irritation studies

11) In vivo studies,

12) Stability studies


Chapter 4

METHODS: 4.1 Determination of λmax and preparation of standard calibration curve for

Carvedilol:41

Principle: Carvedilol exhibits absorption maxima at 242 nm in 30% v/v

Methanolic isotonic phosphate buffer (MIPB) pH 7.4.

Procedure:

1. Preparation of standard solution:

100 mg of Carvedilol was accurately weighed into a 100 ml volumetric flask and

dissolved in small volume of MIPB pH 7.4 with sonication. The volume was made up to

100 ml with MIPB to get a concentration of 1000 µg/ml (SS-I). From the above solution 10

ml was pipetted in a 100 ml volumetric flask and the volume was made up with MIPB to

get a concentration of 100 μg/ml (SS-II). From this, working standard solutions were

prepared.

2. Preparation of working standard solutions:

From (SS-II) aliquots of 0.2, 0.4, 0.6, 0.8., 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 ml were

pipetted out into a series of 10 ml volumetric flasks and the volume was made with MIPB

to get a concentration ranging from 2-20 µg/ml.

The absorbance of the resulting solutions was then measured at 242 nm using UV

spectrophotometer against respective parent solvent as a blank. The standard curve was

obtained by plotting absorbance v/s concentration in µg/ml. The standard calibration curve

is shown in Graph 1 and the values are tabulated in Table 9.

Beer’s range: 2 to 20 µg/ml.


Chapter 4

4.2. Pre-formulation studies:

Prior to the development of the dosage form preformulation studies were carried out

on parameters like solubility, partition coefficient, melting point and diffusion rate constant

of Carvedilol

4.2.1 Partition coefficient:75,78

The oil-water partition coefficient is a measure of lipophilicity of a molecule, which

can be used to predict its capability to cross biological membrane. One of the most

common ways of measuring partition coefficient is shake flask method.

Procedure: The Carvedilol was added little at once into 5 ml of n-octanol until

saturated solution was obtained. This solution was filtered to get a clear solution. Three ml

of the saturated solution was mixed with 2 ml of fresh n-octanol. In total 5 ml of n-

octanol containing Carvedilol was mixed with 15 ml of water. Then two phases were

allowed to equilibrate at 37 oC for 24 h, on cryostatic constant temperature shaker bath

(Research and Test Equipments, Bangalore, India). The concentration of the drug in the

aqueous phase and organic phase was determined by UV spectroscopic method after

necessary dilution. The apparent partition coefficient (Kp) was calculated as the ratio of

drug concentration in each phase by the following equation.

where, Corg is concentration of drug in organic phase and Caq is the concentration

of drug in aqueous phase.


Chapter 4

4.2.2 Melting point determination:

Melting point of drug was determined by taking a small amount of drug in a

capillary tube closed at one end and was placed in melting point apparatus and temperature

at which the drug melts was noted. Values for different physicochemical parameters are

tabulated in table 10.

4.2.3 Permeability studies through porcine ear skin:36,41,47,55,57,72

a) Preparation of the skin barrier:

From a local abattoir, ears were obtained from freshly slaughtered pigs. The ears were

cleaned with water to remove blood stains. The fresh full thickness (0.95 mm) porcine

ear skin was used for the study. The epidermis was prepared by soaking the ear in water

at 600C for 1 min. The intact epidermis from the dorsal side was subsequently teased

off from dermis with forceps, rapidly rinsed with isopropyl alcohol to remove the fat

adhering to the dermal side, washed with water & used immediately.

b) Determination of drug permeability through porcine ear skin:

The permeability study of the drug was carried out across the porcine ear skin using a

Keshary-Chien diffusion cell. A 5 mg/ml drug suspension was prepared in phosphate

buffer pH 7.4 and sonicated to ensure uniform drug distribution. One ml of the above

suspension was taken in the donor compartment. The barrier was mounted between the

donor & the receptor compartments in a way that, the dermal side of the skin was

facing receptor compartment. The receptor cell contained MIPB of pH 7.4 as the

elution medium. The medium was magnetically stirred for uniform drug distribution

and was maintained at 37±10C. The samples were withdrawn every hour upto 8 hours


Chapter 4

and estimated spectrophotometrically (UV) at 242 nm after suitable dilutions to

determine the amount of drug diffused.

The flux (µg/cm2/hr) of Carvedilol was calculated from the slope of the plot of

cumulative amount of drug permitted per square centimeter of skin at steady state

against the time using linear regression analysis.

The steady state permeability coefficient (Kp) of the drug diffused through the

porcine skin was calculated using the equation:

Kp = ---------- (15) J

C

Where, J = Steady state flux

C = Concentration of Carvedilol in donor compartment.

The flux data are tabulated in table 11 and graph 2.

4.2.4 Optimization of transdermal patches with different plasticizers and in

different concentrations:44,45,47,58

Drug free patches of Eudragit RL : RS 100 and HPMC 6cps : Ethyl cellulose

were prepared by casting on mercury surface (mercury substrate method) along with two

different plasticizers i.e. dibutyl phthalate (DBP) and triethyl citrate (TEC).

Polymer solutions were prepared by dissolving in respective solvents by

sonication with the aid of a sonicator for 12 mins. For Eudragit and HPMC : Ethyl cellulose

patches acetone and a mixture of methylene chloride & methanol were used as solvents

respectively. Plasticizers like DBP and TEC at different concentrations based on dry weight

of polymer were used to optimize the patches (Table 12 to 14). The prepared patches were

then evaluated for physical appearance and folding endurance.


Chapter 4

4.2.5 Polymer-Skin compatibility: 15,59,60,61

Compatibility of polymers with skin was determined by performing skin irritation

test. The skin irritation test was performed on two healthy albino rabbits weighing between

2.0 to 3.5 kg. Aqueous solution of formalin 0.8% was used as standard irritant. Drug free

polymeric patches of 4.5 cm2 were used as test patches. 0.8% of formalin is applied on the

left dorsal surface of each rabbit, where as the test patches were placed on identical site, on

the right dorsal surface of the rabbit. The patches were removed after a period of 24 hrs

with the help of alcohol swab. The skin was examined for erythema/oedema. The data are

tabulated in table 15.

4.2.6 Compatibility studies of drug and polymers:

a) FTIR studies: 44, 61,62,64,65

The application of infrared spectroscopy lies more in the qualitative

identification of substances either in pure form or in the mixtures and as a tool in

establishment of the structure. Since I.R. is related to covalent bonds, the spectra can

provide detailed information about the structure of molecular compounds. In order to

establish this point, comparisons were made between the spectrum of the substance and

the pure compound. The infrared data is helpful to confirm the identity of the drug and

to detect the interaction of the drug with the polymers. Infrared spectra of drug &

polymers, alone and in physical mixtures were taken. Then it was investigated for any

possible interaction between polymer and drug. I.R spectral data are shown in spectra

2–6 & their results are tabulated in table 16.


Chapter 4

b) DSC studies: 15,44

The physicochemical compatibility between drug and polymers to be used in the

formulation of transdermal patches was also studied by using differential scanning

calorimetry (DSC). The thermograms obtained for drug, polymers and their physical

mixtures were compared to ascertain any interactions. The DSC thermograms are

shown in spectra 7 to 11 & their results are tabulated in table 17.

Fig no.11: Shimadzu, DSC Q20 V24.4, Japan

4.3 Formulation design:

Preparation of Transdermal patches:

Transdermal patches containing Carvedilol were prepared by mercury substrate

method using varying ratios of different grades of polymers and plasticizers in different

concentrations as shown in the table 7 and 8.


Chapter 4

a) Procedure for preparation of Eudragit patches: 15,44,58

The polymers Eudragit RL and RS 100 (total weight = 1000 mg) were weighed

in requisite ratios and dissolved in 10 ml of acetone to form a 10% w/v solution.

Plasticizers like DBP and TEC were added to the above solution, 25 mg of Carvedilol

is then added under mild agitation until drug dissolves. The solution was poured on the

mercury placed in a glass Petri dish of 63 cm2 area and dried at room temperature for

24 hours. The organic solvent evaporates to leave stable Eudragit RL/RS patches (Table

7).

b) Procedure for preparation of HPMC : Ethyl cellulose (EC) patches:47

Films composed of different ratios of HPMC (6 cps) and EC (total polymer

weight = 600 mg) were prepared by mercury substrate method. HPMC and EC were

weighed and dissolved in 10 ml of an equal volume of methylene chloride and

methanol (5:5 ratio) to form a 6 % w/v solution, which is then plasticized with either

TEC or DBP. 25 mg of Carvedilol is added to the above polymer solution under mild

agitation until the drug dissolves. The resultant solution was poured on the mercury

placed in a glass Petri dish of 63 cm2 area, dried at room temperature for 24 hours and

subsequently oven-dried at 450C for 30 min to remove the residual organic solvents

(Table 8).


Chapter 4

Table 6: Formulation design for Eudragit combination patches

% Conc (w/w) of plasticizer Sl.

No. Ratio of Eudragit RS 100 : RL 100

% Total polymer

Conc(w/v) DBP TEC

Drug (mg)

Formulation Code

1. 1 : 1 10 --- 18 25 RSL 1

2. 2 : 8 10 --- 18 25 RSL 2

3. 3 : 7 10 --- 18 25 RSL 3

4. 4 : 6 10 --- 18 25 RSL 4

5. 5 :5 10 --- 18 25 RSL 5

6. 6 : 4 10 --- 18 25 RSL 6

7. 7 : 3 10 --- 18 25 RSL 7

8. 2 : 8 10 18 --- 25 RSL 8

Table 7: Formulation design for HPMC (6cps) : Ethyl Cellulose (EC) patches

% Conc (w/w)

of plasticizer Sl.

No.

Ratio of

HPMC : EC

% Total

polymer

Conc(w/v) DBP TEC

Drug

(mg)

Formulation

Code

1. 5 : 5 6 --- 25 25 RHE 1

2. 6 : 4 6 --- 25 25 RHE 2

3. 7 : 3 6 --- 25 25 RHE 3

4. 8 : 2 6 --- 25 25 RHE 4

5. 9 : 1 6 --- 25 25 RHE 5

6. 10 : 0 6 --- 25 25 RHE 6

7. 7 : 3 6 25 --- 25 RHE 7


Chapter 4

4.4 Evaluation of transdermal formulation:

I. Physicochemical evaluation:

1. Physical appearance:

All the transdermal systems were visually inspected for colour, clarity, flexibility

and smoothness.

2. Folding Endurance:15,59,63,

Folding endurance of the film was determined manually by folding a small strip of

the film (4×3 cms) at the same place till it breaks. The maximum number of folding

operation done at the same place of the film without breaking, gives the value of folding

endurance, where the cracking point of the films were considered as the end point.

3. Thickness of the films: 39,47,63,

The thickness of the patches was measured at three different places by using a

Digital Screw Gauge micrometer (Mitutoyo, Japan) and mean thickness was calculated.

4. Weight uniformity:15,39

The dried patches were weighed on electronic balance (Sartorius UK). The average

of 3 observations was calculated.

5. Drug content:15,39,67

Transdermal systems of specified area (5.088 cm2) was cut into small pieces and

taken into 50 ml volumetric flask, 25ml of MIPB pH 7.4 was added and gently heated

to 450 C for 15 min and kept for 24 hrs with occasional shaking. Then the volume was

made up to 50ml again with MIPB pH 7.4 and further dilutions were made from this

solution. Similarly, a blank was carried out using a drug free patch. The solutions


Chapter 4

were filtered and absorbances were read at 238 nm by UV spectrophotometer. The

values for different physicochemical parameters are tabulated in Table 18.

6. Percentage moisture uptake:15,63,64,66

The weighed films were kept in a dessicator at room temperature for 24 hours.

They were then taken out and exposed to 84% relative humidity using a saturated

solution of potassium chloride in a dessicator until a constant weight was achieved.

Then the films were weighed and percentage moisture uptake was calculated by using

the following formula:

Percentage moisture uptake = [Final wt.−Initial wt./Initial wt.]×100 -------- (16)

The values are tabulated in table 19 and 20.

7. Percentage moisture content:15,63,64,65,66

The prepared films were weighed individually and kept in a desiccator

containing fused calcium chloride at room temperature for 24 hours. The films were

weighed repeatedly until they showed a constant weight. The percentage moisture

content was calculated using the following formula:

Percentage moisture content = [Initial wt.−Final wt./Final wt.]×100 -------- (17)

The values are tabulated in table 21 and 22.

8. Tensile Strength & Percentage Elongation:15,39

Tensile strength of the film was determined with Universal Strength Testing

Machine (Hounsfield, Slinfold, Horsham, U.K.) as shown in Figure 7. The

sensitivity of the machine was 1 gram. It consisted of two load cell grips. The


Chapter 4

lower one was fixed and upper one was movable. The test film of size (4 × 1 cm2)

was fixed between these cell grips and force was gradually applied till the film

broke. The tensile strength of the film was taken directly from the dial reading in

kg. The values are shown in table 20 & 21. Tensile strength is expressed as follows;

= Tensile load at

Tensile strength

Cross sectional area

Fig no.12 : Universal Strength Testing Machine (Courtesy: B.I.E.T., Davangere)

9. Water vapour transmission studies (WVT or MVT): 39,59,60

MVT is defined as the quantity of moisture transmitted through unit area of film

in unit time.

For this study glass vials of equal diameter were used as transmission cells.

These cells were washed and dried in an oven. About 1gm of fused calcium chloride

was taken in the cells and the polymeric patches (1.30 cm2 area) were fixed over the

brim with the aid of an adhesive. Then the cells were accurately weighed and kept in

a closed desiccator containing saturated solution of potassium chloride (200 ml). The

humidity inside the desiccator was measured by a digital Hygro thermometer and

found to be 84% RH. The cells were taken out and weighed after 1st, 2nd, 3rd, 4th, 5th,


Chapter 4

6th & 7th days of storage and weighed accuratly. The amount of water vapour

transmitted and rate of WVT were calculated and plotted. The values are shown in

table 23 & 24 and graph 3 & 4.

The rate of water vapour transmission (WVT) was calculated using the formula:

WVT Rate = WL S

(18)

Where, W = gm of water transmitted

L = Thickness of the film in cm

S = Exposed surface area of the film in cm2.

10. Skin irritation test: 15,39,60,61

The skin irritation test was performed on two healthy albino rabbits weighing

between 2.0 to 3.5 kg. Aqueous solution of formalin 0.8% was used as standard

irritant. Polymeric patches containing drug of 5.088 cm2 were used as test patches.

0.8% formalin is applied on the left dorsal surface of each rabbit, where as the test

patches were placed on identical site, on the right dorsal surface of the rabbit. The

patches were removed after a period of 24hours with the help of alcohol swab. The

skin was examined for erythema/oedema. The values are tabulated in table 15.

11. Scanning electron microscopy (SEM):44,63,65

The surface morphologies of the transdermal patches were analyzed by using a

JEOL, JSM-6360A, Japan scanning electron microscope. The samples placed on the

stubs were coated finely with gold palladium alloy and examined under the microscope.

Fig No: 10.


Chapter 4

Fig No: 13. JEOL, JSM-6360A, Japan scanning electron microscope

12.

Samples of Carvedilol its pure crystalline state and the transdermal patches were assessed

for ps analytica X- Raydiffractometer (Model:PW 3710). The

ra

ccelerated stability studies of the optimized formulation:68,69

Stability of a pharmaceutical preparation can be defined as “the capability of a

main within its

XRD studies: 49,50

crystallinity using Phili

voltage and current was 25 kv and 25 mA, respectively. Measurements were carried out in

the angular scan range from 10° to 70° (2θ). The XRD spectral data are shown in spect

12 to 16.

13. A

particular formulation in a specific container/closure system to re


Chapter 4

physical, chemical, microbiological, therapeutic and toxicological specifications

throughout its shelf life”.

Studies are designed to increase the rate of chemical degradation or physical

change of an active drug substance or drug product by using exaggerated storage

2 months.

months.

conditions as a part of the formal, definitive, storage program.

ICH specifies the length of study and storage conditions:

Long term testing: 250C ± 20C / 60% RH ± 5% RH for 1

Accelerated testing: 400C ± 20C / 75% RH ± 5% RH for 6

Fig no.14 . Stability Chamber

Procedure:

th TEC as plasticizer (RSL 2)

asticizer (RHE 3) were selected for accelerated stability

studies as per ICH guidelines. These two batches were subjected for 400C ± 20C / 75%

Optimized formulation of Eudragit RL : RS 100 wi

and HPMC : EC with TEC as pl


Chapter 4

RH ± 5% RH for a period of 3 months. These patches were analyzed for physical

appearance, folding endurance, weight variation, content uniformity and finally the

patches were studied for interaction studies.

Results of stability studies are represented in table 45 and spectra 12 and 13.

Adhesive test:

1. Thumb tack test:

II.

as pressed

atch for about 5 seconds and then quickly withdrawn. By varying the

ontact and considering the difficulty of pulling the thumb from

III. I

1.

The release rate determination is one of the most important studies to be

trolled release delivery systems. The dissolution studies of

ne needs to maintain the drug concentration on the

ire and

5

One week after the preparation of transdermal patches, the thumb w

lightly on a p

pressure and time of c

the patch, it was possible to set a scoring as to how easily, quickly and strongly the

polymer can form a bond with the skin. The entire test was simultaneously performed

in blind way on all samples (Table 25).

n-vitro release study:

USP Paddle method:47,64,66

conducted for all con

patches are crucial because o

surface of the stratum corneum consistently and keep it substantially higher than the

drug concentration in the body, to achieve a constant rate of drug permeation.

The dissolution study using USP Paddle Type Dissolution Apparatus was

carried out at 32±10C at 50 rpm frequency of the paddle. 500 ml of MIPB of pH 7.4

was used as the dissolution media. The patches were tied with a thin copper w


Chapter 4

then placed in a jar. Samples were withdrawn at different time intervals and then

analyzed using a UV Spectrophotometer at 238 nm against blank.

Percentage of drug released was determined using the formula:

% of drug released = Da/Dt × 100 --------- (19)

Where, Dt ― indicates the total amount of drug in the patch and

Da — the amount of drug released.

The values are tab in graph 5.

IV. In

using

dialysis membrane as barrier. The optimized patches (patches which showed

subjected for in-vitro release through

porcine

1.

fixed carefully to the receptor compartment of the diffusion cell so that it just touches

area was placed

ulated in table 26 and the release pattern is shown

-vitro membrane/skin permeation study:

In-vitro permeation studies were carried out for all the formulations

highest release in 8 hours) were further

ear skin.

Keshary-Chien diffusion cell using dialysis membrane:71,72,73,74

The dialysis membrane soaked in phosphate buffer pH 7.4 for overnight was

the receptor fluid surface. The transdermal system of 5.088 cm2

above the dialysis membrane fixed to the donor compartment. The receptor

compartment was filled with 48 ml of MIPB of pH 7.4 as diffusion medium. The

receptor medium was magnetically stirred using a magnetic bead for uniform drug

distribution and was maintained at 37±10C. The samples (3 ml) were withdrawn

every hour upto 8 hours and estimated spectrophotometrically (UV) at 238 nm to


Chapter 4

determine the amount of drug released. The volumes withdrawn at each interval were

replaced with an equal volume of fresh, pre warmed buffer solution.

Fig. no.15: Magnetic

rer with Franz

Diffussion cell

eated was plotted against time and

steady state flux as well as Kp value was determined. The values are tabulated in

2.

arlier in permeability

diffusion cell with a

Stir

The cumulative amount of drug perm

table 27 to 41 and the release pattern is shown in graph 6 and 7.

Keshary-Chien diffusion cell using porcine ear skin: 47,55

The porcine ear skin sample was prepared as described e

studies of drug through porcine skin. A Keshary-Chien

diffusional surface area of 5.088 cm2 and receptor volume capacity of 48 ml was used

for the release study. MIPB of pH 7.4 was used as receptor medium. The transdermal

patch was firmly pressed onto the centre of the porcine skin and then the skin along

with the patch was mounted on the donor compartment. The donor compartment was

then placed in position such that the surface of dermis side skin just touches the

receptor fluid surface.


Chapter 4

ase through dialysis membrane. The values are tabulated in

V. In

rocurement, Identification and Housing of Animals

mal House

conditions in 12h light/dark cycle

) guidelines. All the

ning/Training of Animals.

For conducting the BP measurement studies, the animals were required to be kept in

ne side open for entry/exit of the animal with proper

Rest all the experimental set up, procedure and calculations remained similar as

described above in rele

tables 42, 43 and the release pattern is shown in graph 8.

-Vivo permeation study:15

P

Thirty six male albino rats (8 weeks old) 230-250 g were supplied by Ani

facility in our college and kept under standard laboratory

at 25 ± 2 °C. Animals were provided with pellet diet (Lipton, India) and water ad libitum.

Animals were marked with picric acid solution for easy identification.

All the experimental procedures were carried out accordance with committee for the

purpose of control and supervision of experiments on animal (CPCSEA

experimental procedures were approved by the institutional animal ethical committee

(IAEC).

Conditio

a restrainer (rat holder). It had only o

ventilation at all other sides. As the rats were unaccustomed to remain in the restrainer in a

calm and non-aggressive manner, animals were trained for their stay in the restrainer as a

slight movement in and aggression by the animal would have led to variation BP reading.

For this, a rat was inserted in the restrainer headlong until the whole body got conveniently

accommodated inside. The restrainer was locked by screwing the open side of the


Chapter 4

apparatus leaving the tail outside. The exercise was repeated several times until the animals

learnt to stay in restrainer non-aggressively and familiarized with the conditions.

Measurement of Initial Systolic BP of Rats.

The initial BP of all the rats was recorded using Non-invasive blood pressure

, USA). The restrainer carrying the rat was apparatus (Biopac Systems, Inc Santa Barbara

placed in the rat holder with tail protruding out. Systolic blood pressure was measured

indirectly in conscious and slightly restrained, pre-warmed rat by the tail cuff method. An

average of ten consecutive readings was noted.

Fig 16: Albino Wistar rats prepared for in vivo study

Induction of Hypertension in Normotensive Rats.

The anima I was taken as

g five groups (Groups II to VI) by

ls were divided into six groups’ six animals each. Group

control. Hypertension was induced in the remainin

subcutaneous injection of methyl prednisolone acetate (20 mg/Kg/week). Two weeks later,

rats with a minimum mean BP of 150 mmHg were selected.


Chapter 4

Fig no.17: Biopack Machine

ed Hypertensive Rats

After MPA treatment, groups III, IV, V and VI were subjected to TDDS

(formulations RSL-2, RSL-8, RHE-3 and RHE-7, respectively). Group II served as toxic

Post TDDS Treatment BP Assessment of MPA induc

control and received no further treatment. The TDDS was applied to the previously shaven

abdominal area of rat skin with the entire release surface in intimate contact with the

stratum corneum. The patch was applied over the stratum corneum, over the patch an

aluminum foil was placed for avoid the backward movement of drug through the adhesive

tape. A microporous adhesive tape (Johnson and Johnson) was then rolled over to keep the

patch secured at the site of application. The rat was then placed in the restrainer and the

Systolic BP was recorded upto 12 hours. Results of Systolic BP are represented in table 40.


Chapter 4

4.5 Data analysis:70

The matrix systems were reported to follow the zero order release rate and the

the release of the drug.

t order, Higuchi matrix and Korsmeyer’s

elease

e area does not change and no equilibrium conditions are

itial amount of drug in the solution

etics the release rate data were fitted to the following

ount of drug released in time t, Qo is the initial amount of drug

the fi

e release of water-soluble and low

soluble drugs incorporated in semisolids and or solid matrices. Mathematical expressions

diffusion mechanism for

To analyze the mechanism for the release and release rate kinetics of the dosage form, the

data obtained was fitted in to Zero order, Firs

Peppas model. By comparing the r-values obtained, the best-fit model was selected.

1. Zero order kinetics:

Drug dissolution from pharmaceutical dosage forms that do not disaggregate and r

the drug slowly, assuming that th

obtained can be represented by the following equation

Q t = Q o + K o t (20)

Where Q t = amount of drug dissolved in time t, Q o = in

and K o = zero order release constant.

2. First order kinetics:

To study the first order release rate kin

equation.

Log Qt = log Qo + K1t / 2.303 (21)

Where Qt is the am

in the solution and K1 is rst order release constant.

3. Higuchi model:

Higuchi developed several theoretical models to study th


Chapter 4

were obtained for drug particles dispersed in a uniform matrix behaving as the diffusion

Mt / M ∞ = K × t n (23)

e, K is the release constant, t is the release time

e shape of the

1.0, or n=1.0, for mass transfer following a non-Fickian model.

5. Hixson- Crowell model:

To study the Hixson – Crowell model the release rate data are fitted to the following

equation:

(24)

drug in the pharmaceutical dosage form, Ks is a constant incorporating the

study of best

media. And the equation is

Q t = KH × t ½ (22)

Where Q t = Amount of drug released in time t, K H = Higuchi dissolution constant.

4. Korsmeyer and Peppas release model:

To study this model the release rate data are fitted to the following equation

Where Mt / M ∞ is the fraction of drug releas

and n is the diffusional exponent for the drug release that is dependent on th

matrix dosage form.

Peppas (1985) used this n value in order to characterize different release

mechanisms, concluding for values for a slab, of n=0.5 for Fick diffusion and higher values

of n, between 0.5 and

Wo1/3 – Wt

1/3 = Kst

Where Wo is the amount of drug in the pharmaceutical dosage form, Wt is the remaining

amount of

surface-volume relation. Kinetic data of various models applied to release

formulations is shown in table 44.


Chapter-5 Results

5.0 RESULTS

5.1 ANALYTICAL METHODS :

UV scanning of Carvedilol in 30% v/v Methanolic Isotonic Phosphate Buffer (MIPB)

of pH 7.4

Spectra 1: Scanning of Carvedilol by UV-spectrophotometer in 30% v/v


242nm

Dept. of pharmaceutics, KLES’s COP, Hubli. 84

Chapter-5 Results


Table 8: Data for standard Calibration curve of carvedilol in 30% v/v


Absorbance at 242 nm Flask No.

Volume of

SS−II (ml)

Volume made up to (ml)

Conc. (µg/ml) Trial

1 Trial

2 Trial

3 Average S.D.#(±)

1 0.2 10 2 0.024 0.024 0.025 0.024 0.00057

2 0.4 10 4 0.045 0.045 0.045 0.045 0.0000

3 0.6 10 6 0.064 0.065 0.066 0.064 0.0010

4 0.8 10 8 0.088 0.086 0.084 0.086 0.0020

5 1.0 10 10 0.107 0.107 0.108 0.107 0.00057

6 1.2 10 12 0.130 0.130 0.130 0.130 0.0000

7 1.4 10 14 0.154 0.155 0.154 0.154 0.00057

8 1.6 10 16 0.179 0.178 0.178 0.178 0.00057

9 1.8 10 18 0.203 0.203 0.205 0.203 0.00115

10 2.0 10 20 0.227 0.225 0.225 0.225 0.00115

Graph 1: Standard Calibration curve of carvedilol in 30% v/v Methanolic

Isotonic Phosphate Buffer (MIPB) of pH 7.4

Chapter-5 Results

The linear regression analysis for the standard curve:

The linear regression analysis was done on Absorbance data points. The results are as

follows:

For standard curve in 30% v/v methanolic IPB pH 7.4:

The slope = 0.011

The intercept = −0.001

The correlation coefficient = 0.998

A straight line equation (Y = mx + c) was generated to facilitate the calculation of

amount of drug. The equation is as follows:

Absorbance = 0.011 × Concentration − 0.001

Table 9: Data obtained from preformulation studies of Carvedilol.


Chapter-5 Results


Sl. No.

Solubility in MIPB

(mg/ml)

Partition Coefficient (log

P)

Melting Point (0C)

Diffusion rate Constant of

drug (µg/cm2/hr)

1.

~ 1

0.59

115.15

52.27

Chapter-5 Results

Dept. of pharmaceutics, KLES’sCOP, Hubli. 90

5.2.3. Optimization of TDDS patches using Eudragit RL:RS 100 and HPMC:Ethyl

cellulose as polymers with DBP and TEC as plasticizers

Eudragit RL/RS 100 patches: Preformulation study involved using Eudragit RL and RS 100

in various ratios with different concentrations of plasticizers DBP and TEC. In total 56

formulations were prepared involving different ratios of polymers and different concentrations

of plasticizers.

Among the 21 patches containing 3 different concentrations of DBP as plasticizer,

patches with 20% w/w showed good physico-chemical characters, seven of these were

subjected for further development. Similarly out of 5 different concentrations of TEC, patches

with 18% w/w of TEC as plasticizer showed good physico-chemical characters, seven of these

were also subjected for further development (Table 12 and 13).

HPMC/EC patches: All the TDDS patches fabricated with HPMC and EC individually and in

combination were prepared with 15, 20 and 25% w/w of DBP and TEC as plasticizers. Among

36 formulated patches only 6 patches each with DBP and TEC at 25% w/w concentration

showed good physico-chemical characteristics. Hence these were also subjected for further

investigation (Table 14).

Plain HPMC patches with or without plasticizers were very hard, non brittle, made

cracking sound (crackle) when folded. The combination patches of HPMC:EC containing no or

with either DBP and TEC as plasticizers at other than 25% w/w concentration were found to be

hard to brittle, either transparent (in case of TEC) or translucent (in case of DBP) and patches

made cracking sound when folded.

Chapter 5 Results

Dept of Pharmaceutics, KLES’sCOP, Hubli 91

Table 12: Optimization of TDDS patches using Eudragit RL and RS 100 as polymers with DBP as plasticizer

Sl.

No

Ratio of Polymer

Eudragit RS 100 : RL 100

% Total

Polymer

Conc (w/v)

% Conc (w/w)

of plasticizer

TEC

Observations

1. 1 : 9 12 Patches have formed, transparent, non adhesive in nature, initially exhibit good physical properties like flexibility but on storage they were brittle.

2. 2 : 8

3. 3 : 7

15 Patches have formed, transparent, non adhesive in nature, initially exhibit good physical properties like flexibility & elasticity but on storage they

were found to be brittle.

4. 4 : 6

5. 5 : 5

18 Patches have formed, transparent, exhibit good physical properties like flexibility & elasticity, stable on storage. Patches have slight adhesive

property.

6. 6 : 4

7. 7 : 3

10

21

Patches have formed, transparent; apart from good physical properties like increased flexibility & elasticity they exhibit moderate stickiness,

stable on storage.

RS 100 patches were found to be more sticky when compared to RL 100 patches.

Chapter 5 Results


Table 13: Optimization of TDDS patches using Eudragit RL and RS 100 as polymers with TEC as plasticizer

Sl. No

Ratio of Polymer

Eudragit RS 100 : RL 100

% Total Polymer

Conc (w/v)

% Conc (w/w) of plasticizer

TEC

Observations

1. 1 : 9 10 Patches have formed, transparent, brittle, non adhesive in nature.

2. 2 : 8

3. 3 : 7

15 Patches have formed, transparent, exhibit mild elasticity & flexibility, non

adhesive in nature and stable on storage.

4. 4 : 6

5. 5 : 5

18 Patches have formed, transparent, exhibit more elasticity & flexibility and

stable on storage. Patches have slight adhesive property.

6. 6 : 4

7. 7 : 3

10

20

Patches have formed, transparent; apart from good physical properties like increased flexibility & elasticity they exhibit moderate stickiness and

stable on storage.

RS 100 patches are more sticker when compared to RL 100 patches.

Chapter 5 Results


Table 14: Optimization of TDDS patches using HPMC and EC as polymers with DBP & TEC as plasticizers

Sl.

No

Ratio of Polymer

HPMC : EC

% Total Polymer

Conc (w/v)

% Conc (w/w)

of plasticizer

DBP

Observations

1. 10 : 0

2. 9 : 1

3. 8 : 2

25% of DBP

Patches have formed, translucent, non adhesive in nature.

As the ratio of ethyl cellulose increases the softness & flexibility of the patches increase. HPMC patches (10:0, 9:1 and 8:2) were hard, non brittle and crackle to some extent when folded where as other patches (7:3, 6:4 and 5:5) were soft, flexible in nature and do not crackle when folded.

4. 7 : 3

5. 6 : 4

6

25% of TEC Patches have formed, transparent, soft, flexible, non adhesive in nature and stable on storage. Patches do not crackle when folded.

Chapter 5 Results


6. 5 : 5

Table 15: Data obtained from skin irritation test for drug free and optimized polymeric patches:

Sl.No Formulation Control Test 1 Test 2

1 Patch without drug Eudragit RS : RL100 (1:1)

++ --- ---

2 Patch without drug HPMC : EC (5:5) ++ --- ---

3 Optimized patch with Eudragit RS:RL 100 & drug (RLS 2)

+++ --- ---

4 Optimized patch with HPMC:EC & drug

(RHE 3)

++ --- +

--- = No Erythema

+ = Very slight erythema

Chapter 5 Results


+ + = Well defined erythema

+ + + = Moderate to severe erythema

Compatibility studies of drug and polymers by FTIR spectroscopy:

Spectra 2: FTIR spectra of Carvedilol

Chapter 5 Results


Spectra 3: FTIR spectra of Eudragit RL 100 and Eudragit RS 100

Chapter 5 Results


Spectra 4: FTIR spectra of Eudragit RL 100, Eudragit RS 100 and Carvedilol

Chapter 5 Results


Spectra 5: FTIR spectra of HPMC (6 cps) and Ethyl cellulose

Chapter 5 Results


Spectra 6: FTIR spectra of HPMC (6 cps), Ethyl cellulose and Carvedilol

Chapter 5 Results


Table 16: Data obtained from compatibility studies of drug and polymers by FTIR spectroscopy

Chapter 5 Results


Important IR spectral peaks of different groups expressed in wave number (cm-1)

Drug/Polymer N-H/-N-

20amide/quaternary

ammonium group

C-O-C

stretch

(ether)

C-H

stretch

(aliphatic)

OH

stretch

(alcohol/

acid)

C=O

stretch

(acid)

C=O

stretch

(amide/ester)

Aromatic

C=C

stretch

C-O-H

bend

Carvedilol 3344.93

1214.70

and

1034.36

2922.56

Broad peak

(3200 —

2583.03)

1603.53 1636.78

1562.20

and

1493.74

---

Eudragit

RL+RS 100 3440.93 --- 2992.69 --- --- 1733.45 --- ---

Carvedilol +

Eudragit

RL+RS 100

3343.34

1213.57

and

1099.66

2925.10

Broad peak

(3200 —

2500)

1594.23 1637.40 (D)

1730 (P) (W)

1564.44

and

1492.35

---

HPMC (6 cps)

+ EC ---

1065

and

1118.40

2930.23

and

2978.37

3479.40 (B) --- --- --- 1379.90

Carvedilol +

HPMC (6cps)

+ EC

3343.46(W)

1213.63(D)(W)

1087.81 (P)

1096.73 (P)(W)

2923.53

3478.81 (B) 1595.85 1639.77

1568.30

and

1451.48

1380.31

(D) — drug peak (Carvedilol) (W) — a weak peak EC — Ethyl cellulose

(P) — polymer peak (B) — broad peak due to hydrogen bonding.

Compatibility studies of drug and polymers by differential scanning calorimetry (DSC) studies:

Chapter 5 Results


Spectra 7: DSC thermogram of Carvedilol

Spectra 8: DSC thermogram of Eudragit RL 100 and Eudragit RS 100

Chapter 5 Results


Spectra 9: DSC thermogram of Carvedilol, Eudragit RL 100 and Eudragit RS 100

Chapter 5 Results


Spectra 10: DSC thermogram of HPMC (6 cps) and Ethyl cellulose

Chapter 5 Results


Spectra 11: DSC thermogram of Carvedilol, HPMC (6 cps) and Ethyl cellulose

Chapter 5 Results


Table 17: Data obtained from compatibility studies of drug and polymer by DSC thermograms.

Chapter 5 Results


Drug/Drug-Polymer combination

Observed Peaks

Carvedilol

(drug) 120.050C --- --- ---

Eudragit RL 100

+

RS 100

--- 260.920C --- ---

Carvedilol

+

Eudragit RL 100+RS

100

120.930C (drug) --- --- ---

HPMC (6cps)

+

Ethyl cellulose (EC) --- ---

192.080C (HPMC)

272.300C (EC)

Carvedilol

+

HPMC (6 cps) + EC

119.860C (drug)

--- --- 250.390C

(EC)

Chapter 5 Results


Compatibility studies of drug and polymers by X-Ray Difractometry (XRD):

Chapter 5 Results


Spectra 12: XRD spectra of Carvedilol.

Chapter 5 Results


Spectra 13: XRD spectra of Carvedilol+Eudragit RS 100 +RL 100

Chapter 5 Results


Spectra 14:XRD spectra of Carvedilol+HPMC+EC

Chapter 5 Results


Spectra 15: XRD spectra of Eudragit RS 100 +RL 100

Chapter 5 Results


Spectra 16: XRD spectra of HPMC+EC

Chapter 5 Results


Table 18: Summary of data showing physical parameters and drug content of TDDS

SL.

No.

Formulation

Code

*Folding

Endurance ± S.D

(No. of foldings)

Weight (gm) *Thickness (mm)

± S.D

*Drug content (%)

± S.D

1. RSL 1 217 ± 7.506 0.863 0.0833 ± 0.0115 89.48 ± 0.6351

2. RSL 2 241 ± 7.024 0.859 0.1103 ± 0.0351 96.36 ± 0.7045

3. RSL 3 206 ± 12.000 0.950 0.1033 ± 0.0208 92.23 ± 0.9022

4. RSL 4 140 ± 11.140 0.762 0.1100 ± 0.0100 92.16 ± 0.3119

5. RSL 5 159 ± 5.850 0.887 0.0933 ± 0.0251 91.81 ± 0.4038

6. RSL 6 178 ± 6.506 0.902 0.1133 ± 0.0152 90.94 ± 0.2237

7. RSL 7 156 ± 17.217 0.813 0.1367 ± 0.0503 88.78 ± 0.6602

8. RSL 8 239 ± 12.290 0.837 0.1166 ± 0.0472 93.84 ± 0.6842

9. RHE 1 95 ± 2.517 0.566 0.0910 ± 0.0168 92.74 ± 0.5703

10. RHE 2 120 ± 4.726 0.592 0.0973 ± 0.0283 93.72 ± 1.270

11. RHE 3 179 ± 8.082 0.597 0.0923 ± 0.0155 96.34 ± 1.007

12. RHE 4 227 ± 6.391 0.637 0.1000 ± 0.0174 92.27 ± 0.4022

13. RHE 5 170 ± 15.020 0.612 0.1037 ± 0.0232 91.45 ± 0.5950

14. RHE 6 216 ± 13.111 0.603 0.1183 ± 0.0293 90.77 ± 0.5972

15. RHE 7 103 ± 3.512 0.589 0.0993 ± 0.0070 95.84 ± 0.2831

* = Average of 3 observations.

Chapter 5 Results


Table 19: Data obtained from percentage moisture uptake for Eudragit RS : RL 100 patches

Moisture uptake (gm) for films containing drug

Sl. No. Formulation

Code Initial wt in gm Final wt in gm

% Moisture uptake

1. RSL 1 0.227 0.229 0.88

2. RSL 2 0.235 0.238 1.27

3. RSL 3 0.215 0.217 0.93

4. RSL 4 0.214 0.217 1.41

5. RSL 5 0.195 0.197 1.02

6. RSL 6 0.199 0.201 1.00

7. RSL 7 0.221 0.223 0.90

8. RSL 8 0.218 0.220 0.91

Chapter 5 Results


Table 20: Data obtained from percentage moisture uptake for HPMC : Ethyl cellulose patches

Moisture uptake (gm) for films containing drug

Sl. No. Formulation


% Moisture uptake

1. RHE 1 0.172 0.174 1.12

2. RHE 2 0.163 0.165 1.23

3. RHE 3 0.167 0.169 1.19

4. RHE 4 0.175 0.178 1.71

5. RHE 5 0.129 0.132 2.32

6. RHE 6 0.137 0.139 1.42

7. RHE 7 0.147 0.149 1.36

Chapter 5 Results


Table 21: Data obtained from percentage moisture content for Eudragit RS : RL 100 patches.

Moisture content (gm) for films containing drug

Sl. No. Formulation


% Moisture content

1. RSL 1 0.060 0.058 3.44

2. RSL 2 0.064 0.062 3.22

3. RSL 3 0.045 0.043 4.65

4. RSL 4 0.051 0.046 10.86

5. RSL 5 0.054 0.051 5.88

6. RSL 6 0.024 0.021 14.28

7. RSL 7 0.041 0.036 13.88

8. RSL 8 0.061 0.055 10.90

Chapter 5 Results


Table 22: Data obtained from percentage moisture content for HPMC : Ethyl cellulose patches

Moisture content for films containing drug

Sl. No. Formulation


% Moisture content

1. RHE 1 0.053 0.048 10.41

2. RHE 2 0.060 0.054 11.11

3. RHE 3 0.061 0.057 7.01

4. RHE 4 0.057 0.054 5.55

5. RHE 5 0.058 0.055 5.45

6. RHE 6 0.054 0.050 8.00

7. RHE 7 0.053 0.047 12.76

Chapter 5 Results


Table 23: Data obtained from Tensile strength and Elongation of Eudragit RL: RS 100 patches

Sl. No

Formulation Code

Tensile strength

(Kg ± SD)

Elongation (mm ±SD)

1. RSL 1 0.4245 ± 0.0122 15.48 ± 1.1511

2. RSL 2 0.3874 ± 0.0118 18.61 ± 0.7703

3. RSL 3 0.3604 ± 0.0164 22.46 ± 1.1452

4. RSL 4 0.2877 ± 0.0101 27.17 ± 1.3499

5. RSL 5 0.2736 ± 0.0119 31.76 ± 0.8637

6. RSL 6 0.2381 ± 0.0102 35.92 ± 1.2550

7. RSL 7 0.1999 ± 0.0107 41.88 ± 1.6258

Chapter 5 Results


Table 24: Data obtained from Tensile strength and Elongation of HPMC: EC patches

8. RSL 8 0.3747 ± 0.0068 18.56 ± 0.8748

Chapter 5 Results


Table 25: Data obtained from water vapor transmission studies for Eudragit RS : RL 100 patches.

Sl. No

Formulation

Code

Tensile strength

(Kg ± SD)

Elongation (mm ± SD)

1. RHE 1 0.2333 ± 0.0125

35.29 ± 0.8045

2. RHE 2 0.3246 ± 0.0126

32.45 ± 0.8558

3. RHE 3 0.3842 ± 0.0130

26.51 ± 2.1601

4. RHE 4 0.4758 ± 0.0093

24.56 ± 0.7006

5. RHE 5 0.5759 ± 0.0134

23.35 ± 1.7043

6. RHE 6 0.385 ± 0.0100

20.49 ± 1.0864

7. RHE 7 0.3784 ± 0.0130

27.51 ± 1.7601

Chapter 5 Results


Amount of water vapor transmission for drug containing

patches in gm

Sl. No

Formulation

Code 1st day 2nd day 3rd day 4th day 5th day 6th day 7th day

WVT rate constant

(gm.cm/cm2.24 hrs)

1. RSL 1 0.017 0.027 0.042 0.052 0.062 0.073 0.084 5.381 × 10-3

2. RSL 2 0.014 0.031 0.040 0.054 0.063 0.075 0.087 6.652 × 10-3

3. RSL 3 0.015 0.021 0.032 0.039 0.048 0.059 0.070 6.674 × 10-3

4. RSL 4 0.013 0.033 0.040 0.056 0.063 0.076 0.090 7.124 × 10-3

5. RSL 5 0.016 0.032 0.041 0.056 0.065 0.079 0.093 6.021 × 10-3

6. RSL 6 0.018 0.037 0.045 0.058 0.066 0.082 0.100 6.647 × 10-3

7. RSL 7 0.015 0.039 0.047 0.063 0.071 0.085 0.106 8.814 × 10-3

8. RSL 8 0.016 0.032 0.042 0.054 0.066 0.084 0.102 7.531 × 10-3

Graph 3: Water vapour transmission profile for Eudragit RL: RS 100 patches

Chapter 5 Results


Table 26: Data obtained from water vapour transmission studies for HPMC : Ethyl cellulose patches

Chapter 5 Results


Amount of water vapour transmission for drug containing patches

in gm

Sl. No

Formulation

Code 1st day 2nd day 3rd day 4th day 5th day 6th day 7th day

WVT rate constant

(gm.cm/cm2.24 hrs)

1. RHE 1 0.023 0.056 0.083 0.106 0.133 0.156 0.177

5..880 × 10-3

2. RHE 2 0.015 0.049 0.073 0.094 0.115 0.138 0.160

6.284 × 10-3

3. RHE 3 0.016 0.045 0.069 0.093 0.120 0.145 0.167

5.963× 10-3

4. RHE 4 0.017 0.048 0.072 0.093 0.128 0.155 0.175

6.472 × 10-3

5. RHE 5 0.015 0.043 0.067 0.084 0.112 0.126 0.170

6.700 × 10-3

6. RHE 6 0.024 0.063 0.094 0.120

0.163 0.184 0.206 7.644. × 10-3

7. RHE 7 0.022 0.049 0.070 0.094 0.130 0.153 0.173 6.416 × 10-3

Graph 4: Water vapour transmission profile for HPMC: Ethyl cellulose patches

Chapter 5 Results


Chapter 5 Results


Fig 18: Photographs of Eudragit RS: RL 100 patches

Formulation RSL2 Formulation RSL8

Chapter 5 Results


Fig 19: Photographs of HPMC: Ethyl cellulose patches

Formulation RHE 3 Formulation RHE 7

Chapter 5 Results


Fig 20: Scanning Electron Microscopy of formulation RSL 2

Chapter 5 Results


Chapter 5 Results


Fig 21: SEM photograph of the transdermal film (RSL2) showing the patch behaviour after the release of drug

Chapter 5 Results


Fig 22: Scanning Electron Microscopy of formulation RHE 3

Chapter 5 Results


Table 27: Data obtained from Adhesive property of patches by Thumb tack test

Eudragit RS : RL 100 patches

RSL 1 RSL 2 RSL 3 RSL 4 RSL 5 RSL 6 RSL 7 RSL 8

Observations

+ + + + + + + +

A. HPMC : EC patches

RHE 1 RHE 2 RHE 3 RHE 4 RHE 5 RHE 6 RHE 7

Observations

--- --- + --- + --- +

--- = No adhesive property

Chapter 5 Results


+ = Slight adhesive property

Table 28: Data obtained from dissolution study of optimized patches using USP paddle method

Percentage of drug released

Eudragit RS 100 : RL 100 HPMC : Ethyl Cellulose

Sl. No.

Time in hours

RSL 1 RSL 8 RHE 3 RHE 7

1. 1 45.73 66.54 83.78 81.80 2. 2 69.60 69.43 92.20 90.43 3. 3 77.19 71.25 91.12 96.17 4. 4 80.66 75.79 91.19 95.63 5. 5 83.58 79.88 --- --- 6. 6 86.85 84.15 --- --- 7. 7 89.07 88.60 --- --- 8. 8 91.53 89.88 --- --- 9. 9 93.56 89.10 --- --- 10. 10 93.76 88.56 --- --- 11. 12 92.73 88.41 --- --- 12. 24 92.63 88.05 --- ---

Chapter 5 Results


Graph 5: Dissolution profile for Eudragit RL:RS 100 and HPMC : EC patches

Chapter 5 Results


Chapter 5 Results


Table 29: In vitro release study of formulation RSL 1 through dialysis membrane

Sl. No

Time in

Hours Absorbance Conc in

µgm/3 ml Error Conc in µgm/48 ml

CDR µgm

CDR µgm/cm2/hr

% CDR

1. 1 0.212 9.59 0 234.97 234.97 50.86 13.84

2. 2 0.245 11.09 9.59 271.72 281.31 60.89 16.57

3. 3 0.285 12.90 20.68 316.27 336.95 72.93 19.85

4. 4 0.309 14 33.59 343 376.59 81.51 22.19

5. 5 0.341 15.45 47.59 378.63 426.22 92.25 25.11

6. 6 0.379 17.18 63.04 420.95 484 104.76 28.52

7. 7 0.443 20.09 80.22727 492.22 572.45 123.90 33.73

8. 8 0.486 22.04 100.31 540.11 640.43 138.62 37.73

9. 9 0.529 24 122.36 588 710.36 153.75 41.85

10. 10 0.572 25.95 146.36 635.88 782.25 169.31 46.09

11. 11 0.637 28.90 172.31 708.27 880.59 190.60 51.89

12. 12 0.673 30.54 201.22 748.36 949.59 205.53 55.95

13. 24 0.963 43.72 231.77 1071.3 1303.09 282.05 76.78

The concentration of drug at the donor compartment was = 1697 µgm.

Steady state flux was = 3.163 µgm/cm2/hr Kp = 0.001837.

Chapter 5 Results


Table 30: In vitro release study of formulation RLS 2 through dialysis membrane

Sl. No

Time in



CDR µgm

CDR µgm/cm2/hr % CDR

1. 1 0.256 11.59 0 283.97 283.97 61.46 16.73

2. 2 0.289 13.09 11.59 320.72 332.31 71.93 19.58

3. 3 0.315 14.27 24.68 349.68 374.36 81.031 22.060

4. 4 0.347 15.72 38.95 385.31 424.27 91.833 25.00

5. 5 0.368 16.68 54.68 408.70 463.38 100.30 27.30

6. 6 0.409 18.54 71.36 454.36 525.72 113.79 30.97

7. 7 0.449 20.36 89.90 498.90 588.81 127.44 34.69

8. 8 0.492 22.31 110.2 546.79 657.06 142.22 38.71

9. 9 0.537 24.36 132.59 596.90 729.5 157.90 42.987

10. 10 0.588 26.68 156.95 653.70 810.65 175.46 47.77

11. 11 0.643 29.18 183.63 714.95 898.59 194.50 52.95

12. 12 0.698 31.68 212.81 776.20 989.02 214.07 58.28

13. 24 0.996 45.22 244.5 1108.068 1352.56 292.76 79.70



Chapter 5 Results



Sl. No

Time in



CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.208 9.40 0 230.52 230.52 49.89 13.58

2. 2 0.231 10.45 9.40 256.13 265.54 57.47 15.64

3. 3 0.278 12.59 19.86 308.47 328.34 71.06 19.34

4. 4 0.302 13.68 32.45 335.20 367.65 79.57 21.66

5. 5 0.332 15.04 46.13 368.61 414.75 89.77 24.44

6. 6 0.357 16.18 61.18 396.45 457.63 99.05 26.96

7. 7 0.398 18.04 77.36 442.11 519.47 112.44 30.61

8. 8 0.461 20.90 95.40 512.27 607.68 131.53 35.80

9. 9 0.589 26.72 116.3 654.81 771.13 166.91 45.44

10. 10 0.621 28.18 143.0 690.45 833.5 180.41 49.11

11. 11 0.653 29.63 171.22 726.09 897.31 194.22 52.87

12. 12 0.669 30.36 200.86 743.90 944.77 204.49 55.67

13. 24 0.927 42.09 231.22 1031.22 1262.45 273.25 74.39



Chapter 5 Results



Sl. No

Time inHours Absorbance Conc in


CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.196 8.86 0 217.15 217.15 47.00 12.79

2. 2 0.221 10 8.86 245 253.86 54.94 14.95

3. 3 0.268 12.13 18.86 297.34 316.20 68.44 18.63

4. 4 0.294 13.31 31 326.29 357.29 77.33 21.05

5. 5 0.328 14.86 44.31 364.15 408.47 88.41 24.07

6. 6 0.347 15.72 59.18 385.31 444.5 96.21 26.19

7. 7 0.381 17.27 74.90 423.18 498.09 107.81 29.35

8. 8 0.438 19.86 92.18 486.65 578.84 125.29 34.10

9. 9 0.485 22 112.04 539 651.04 140.91 38.36

10. 10 0.543 24.63 134.04 603.59 737.63 159.66 43.46

11. 11 0.599 27.18 158.68 665.95 824.63 178.49 48.59

12. 12 0.647 29.36 185.86 719.40 905.27 195.94 53.34

13. 24 0.903 41 215.22 1004.5 1219.7 264.01 71.8



Chapter 5 Results



Sl. No

Time in Hours Absorbance Conc in


CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.189 8.54 0 209.36 209.36 45.31 12.33

2. 2 0.209 9.45 8.54 231.63 240.18 51.98 14.15

3. 3 0.253 11.45 18 280.63 298.63 64.63 17.59

4. 4 0.275 12.45 29.45 305.13 334.59 72.42 19.716

5. 5 0.306 13.86 41.90 339.65 381.56 82.59 22.48

6. 6 0.331 15 55.77 367.5 423.27 91.61 24.94

7. 7 0.363 16.45 70.77 403.13 473.90 102.57 27.926

8. 8 0.397 18 87.22 441 528.22 114.33 31.127

9. 9 0.454 20.59 105.22 504.47 609.70 131.97 35.92

10. 10 0.499 22.63 125.81 554.59 680.40 147.27 40.09

11. 11 0.548 24.86 148.45 609.15 757.61 163.98 44.64

12. 12 0.583 26.45 173.31 648.13 821.45 177.80 48.40

13. 24 0.882 40.04 199.77 981.11 1180.88 255.60 69.58



Chapter 5 Results



Sl. No

Time in



CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.172 7.77 0 190.43 190.43 41.21 11.22

2. 2 0.195 8.81 7.77 216.04 223.81 48.44 13.18

3. 3 0.243 11 16.59 269.5 286.09 61.92 16.85

4. 4 0.266 12.04 27.59 295.11 322.70 69.84 19.016

5. 5 0.293 13.27 39.63 325.18 364.81 78.96 21.49

6. 6 0.316 14.31 52.90 350.79 403.70 87.381 23.78

7. 7 0.348 15.77 67.22 386.43 453.65 98.194 26.733

8. 8 0.371 16.81 83 412.04 495.04 107.15 29.17

9. 9 0.411 18.63 99.81 456.59 556.40 120.43 32.78

10. 10 0.463 21 118.45 514.5 632.95 137.00 37.29

11. 11 0.496 22.5 139.45 551.25 690.70 149.50 40.70

12. 12 0.529 24 161.95 588 749.95 162.32 44.19

13. 24 0.851 38.63 185.95 946.59 1132.5 245.13 66.73


Chapter 5 Results


Steady state flux was = 2.673. µgm/cm2/hr Kp = 0.001575.


Sl. No

Time in



CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.159 7.18 0 175.95 175.95 38.08 10.36

2. 2 0.176 7.95 7.18 194.88 202.06 43.73 11.90

3. 3 0.211 9.54 15.13 233.86 249 53.89 14.67

4. 4 0.262 11.86364 24.68 290.65 315.34 68.255 18.58

5. 5 0.279 12.63 36.54 309.59 346.13 74.921 20.39

6. 6 0.305 13.81 49.18 338.54 387.72 83.923 22.84

7. 7 0.328 14.86 63 364.15 427.15 92.458 25.17

8. 8 0.341 15.45 77.86 378.63 456.5 98.80 26.90

9. 9 0.372 16.86 93.31 413.15 506.47 109.62 29.84

10. 10 0.399 18.09 110.18 443.22 553.40 119.78 32.61

11. 11 0.426 19.31 128.27 473.29 601.56 130.20 35.44

12. 12 0.479 21.72 147.5909 532.31 679.90 147.16 40.06

13. 24 0.823 37.36 169.31 915.40 1084.72 234.78 63.92


Chapter 5 Results


Steady state flux was = 11.372.5113 µgm/cm2/hr Kp = 0.001489.


Sl. No

Time in



CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.249 11.27 0 276.18 276.18 59.77 16.27

2. 2 0.281 12.72 11.27 311.81 323.09 69.93 19.03

3. 3 0.306 13.86 24 339.65 363.65 78.714 21.42

4. 4 0.339 15.36 37.86 376.40 414.27 89.66 24.41

5. 5 0.357 16.18 53.22 396.45 449.68 97.33 26.49

6. 6 0.396 17.95 69.40 439.88 509.29 110.23 30.01

7. 7 0.435 19.72 87.36 483.31 570.68 123.52 33.62

8. 8 0.479 21.72 107.09 532.31 639.40 138.40 37.67

9. 9 0.518 23.5 128.81 575.75 704.56 152.50 41.51

10. 10 0.562 25.5 152.31 624.75 777.06 168.19 45.79

11. 11 0.621 28.18 177.81 690.45 868.27 187.93 51.16

12. 12 0.673 30.54 206 748.36 954.36 206.57 56.23

13. 24 0.967 43.90 236.54 1075.77 1312.3 284.05 77.33

Chapter 5 Results




Graph 6A: In vitro release profile for Eudragit patches containing 25 mgs of Carvedilol through dialysis membrane

Chapter 5 Results


Graph 6B: In vitro release profile for Eudragit patches containing 25 mgs of Carvedilol through dialysis membrane

Chapter 5 Results


Chapter 5 Results


Table 37: In vitro release study of formulation RHE 1 through dialysis membrane

Sl. No

Time inHours Absorbance Conc in


CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.18 8.13 0 199.34 199.34 43.147 11.74

2. 2 0.194 8.77 8.13 214.93 223.06 48.28 13.14

3. 3 0.199 9 16.90 220.5 237.40 51.38 13.98

4. 4 0.21 9.5 25.90 232.75 258.65 55.98 15.24

5. 5 0.236 10.68 35.40 261.70 297.11 64.31 17.50

6. 6 0.254 11.5 46.09 281.75 327.84 70.96 19.31

7. 7 0.265 12 57.59 294 351.59 76.10 20.71

8. 8 0.278 12.59 69.59 308.47 378.06 81.83 22.27

9 9 0.29 13.13 82.18 321.84 404.02 87.45 23.80

10 10 0.304 13.77 95.31 337.43 432.75 93.66 25.50

11 11 0.315 14.27 109.09 349.68 458.77 99.30 27.03

12 12 0.326 14.77 123.36 361.93 485.29 105.04 28.59

13 24 0.347 15.72 138.13 385.31 523.45 113.30 30.84 The concentration of drug at the donor compartment was = 1697µgm.

Chapter 5 Results




Sl. No

Time in Hours Absorbance Conc in


CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.198 8.95 0 219.38 219.38 47.48 12.92

2. 2 0.214 9.68 8.95 237.20 246.15 53.28 14.50

3. 3 0.22 9.95 18.63 243.88 262.52 56.82 15.46

4. 4 0.251 11.36 28.59 278.40 307 66.45 18.09

5. 5 0.267 12.09 39.95 296.22 336.18 72.76 19.81

6. 6 0.281 12.72 52.04 311.81 363.86 78.75 21.44

7. 7 0.296 13.40 64.77 328.52 393.29 85.12 23.17

8. 8 0.315 14.27 78.18 349.68 427.86 92.61 25.21

9. 9 0.326 14.77 92.45 361.93 454.38 98.35 26.77

10 10 0.351 15.90 107.22 389.77 497 107.57 29.28

11. 11 0.368 16.68 123.13 408.70 531.84 115.11 31.34

12. 12 0.394 17.86 139.81 437.65 577.47 124.99 34.02

13. 24 0.402 18.22 157.68 446.56 604.25 130.79 35.60

Chapter 5 Results



Steady state flux was =1.35 µgm/cm2/hr Kp = 0.000795.


Sl. No

Time inHours Absorbance

Conc in µgm/3 ml Error

Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.298 13.5 0 330.75 330.75 71.59 19.49

2. 2 0.354 16.04 13.5 393.11 406.61 88.01 23.96

3. 3 0.397 18 29.54 441 470.54 101.84 27.72

4. 4 0.445 20.18 47.54 494.45 542 117.31 31.93

5. 5 0.485 22 67.72 539 606.72 131.32 35.75

6. 6 0.512 23.22 89.72 569.06 658.79 142.59 38.82

7. 7 0.535 24.27 112.9 594.68 707.63 153.16 41.69

8. 8 0.562 25.5 137.22 624.75 761.97 164.93 44.90

9 9 0.586 26.59 162.7 651.47 814.20 176.23 47.97

10 10 0.612 27.77 189.31 680.43 869.75 188.25 51.25

11. 11 0.632 28.68 217.09 702.70 919.79 199.08 54.20

12. 12 0.698 31.68 245.77 776.20 1021.97 221.20 60.22

Chapter 5 Results


13. 24 0.752 34.13 277.45 836.34 1113.79 241.08 65.63




Sl. No



Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.088 3.95 0 96.88 96.88 20.97 5.70

2. 2 0.099 4.45 3.95 109.13 113.09 24.47 6.66

3. 3 0.126 5.68 8.40 139.20 147.61 31.95 8.69

4. 4 0.152 6.86 14.09 168.15 182.25 39.44 10.73

5. 5 0.18 8.13 20.95 199.34 220.29 47.68 12.98

6. 6 0.196 8.86 29.09 217.15 246.25 53.30 14.51

7. 7 0.253 11.45 37.95 280.63 318.59 68.95 18.77

8. 8 0.285 12.90 49.40 316.27 365.68 79.15 21.54

9. 9 0.314 14.22 62.318 348.56 410.88 88.93 24.21

10. 10 0.362 16.40 76.54 402.02 478.56 103.58 28.20

11. 11 0.39 17.68 92.95 433.20 526.15 113.88 31.00

Chapter 5 Results


12. 12 0.421 19.09 110.63 467.72 578.36 125.18 34.08

13. 24 0.453 20.54 129.72 503.36 633.09 137.03 37.30




Sl. No



Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.123 5.54 0 135.86 135.86 29.40 8.00 2. 2 0.153 6.90 5.54 169.27 174.81 37.83 10.30 3. 3 0.174 7.86 12.45 192.65 205.11 44.39 12.08 4. 4 0.196 8.86 20.31 217.15 237.47 51.40 13.99

5. 5 0.222 10.04 29.18 246.11 275.29 59.58 16.22 6. 6 0.235 10.63 39.22 260.59 299.8182 64.89 17.66 7. 7 0.265 12 49.86 294 343.86 74.42 20.26

8. 8 0.298 13.5 61.86 330.75 392.61 84.98 23.13

9. 9 0.32 14.5 75.36 355.25 430.61 93.20 25.37

10. 10 0.356 16.13 89.86 395.34 485.20 105.02 28.59

Chapter 5 Results


11. 11 0.379 17.18 106 420.95 526.95 114.05 31.05

12. 12 0.395 17.90 123.18 438.77 561.95 121.63 33.11

13. 24 0.421 19.09 141.09 467.72 608.81 131.77 35.87




Sl. No



Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.132 5.95 0 145.88 145.88 31.57 8.596

2. 2 0.162 7.31 5.95 179.29 185.25 40.09 10.91

3. 3 0.233 10.54545 13.27 258.36 271.63 58.79 16.00

4. 4 0.277 12.54 23.81 307.36 331.18 71.68 19.515

5. 5 0.294 13.31 36.36 326.29 362.65 78.49 21.37

6. 6 0.314 14.22 49.68 348.56 398.25 86.20 23.46

7. 7 0.356 16.13 63.90 395.34 459.25 99.40 27.06

8. 8 0.378 17.13 80.04 419.84 499.88 108.20 29.45

9. 9 0.421 19.09 97.18 467.72 564.90 122.27 33.28

Chapter 5 Results


10. 10 0.465 21.09 116.27 516.72 633 137.01 37.30

11. 11 0.498 22.59 137.36 553.47 690.84 149.53 40.70

12. 12 0.535 24.27 159.95 594.68 754.63 163.34 44.46

13. 24 0.589 26.72 184.22 654.81 839.04 181.61 49.44




Sl. No

Time inHours

Absorbance Conc in

µgm/3 ml Error

Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.184 8.31 0 203.79 203.79 44.11 12.00 2. 2 0.212 9.59 8.318 234.97 243.29 52.66 14.33 3. 3 0.265 12 17.90 294 311.90 67.51279 18.38 4. 4 0.321 14.54 29.90 356.36 386.27 83.60 22.76

5. 5 0.375 17 44.45 416.5 460.95 99.77 27.16 6. 6 0.401 18.18 61.45 445.45 506.90 109.72 29.87 7. 7 0.431 19.54 79.63 478.86 558.5 120.88 32.91

8. 8 0.463 21 99.18 514.5 613.68 132.83 36.16

Chapter 5 Results


9. 9 0.498 22.59 120.18 553.47 673.65 145.81 39.69

10. 10 0.536 24.318 142.77 595.79 738.56 159.86 43.52

11. 11 0.578 26.22 167.09 642.56 809.65 175.25 47.71

12. 12 0.634 28.77 193.31 704.93 898.25 194.42 52.93

13. 24 0.689 31.27 222.09 766.18 988.27 213.91 58.23



Graph 7: In vitro release profile for HPMC : Ethyl cellulose patches containing 25 mgs of Carvedilol through dialysis membrane

Chapter 5 Results


Table 44: In vitro release study of formulation optimized with Eudragit RS : RL 100 (RSL 2) through

Chapter 5 Results


Porcine ear skin

Sl. No



Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.191 8.636364 0 211.5909 211.5909 45.7989 12.46853 2. 2 0.212 9.590909 8.636364 234.9773 243.6136 52.73022 14.35555 3. 3 0.265 12 18.22727 294 312.2273 67.58166 18.39878 4. 4 0.321 14.54545 30.22727 356.3636 386.5909 83.67769 22.78084

5. 5 0.375 17 44.77273 416.5 461.2727 99.84258 27.18166 6. 6 0.401 18.18182 61.77273 445.4545 507.2273 109.7895 29.88964 7. 7 0.431 19.54545 79.95455 478.8636 558.8182 120.9563 32.92977

8. 8 0.463 21 99.5 514.5 614 132.9004 36.1815

9. 9 0.498 22.59091 120.5 553.4773 673.9773 145.8825 39.71581

10. 10 0.536 24.31818 143.0909 595.7955 738.8864 159.9321 43.54074

11. 11 0.578 26.22727 167.4091 642.5682 809.9773 175.3198 47.72995

12. 12 0.634 28.77273 193.6364 704.9318 898.5682 194.4953 52.95039

13. 24 0.689 31.27273 222.4091 766.1818 988.5909 213.9807 58.25521



Chapter 5 Results


Table 45: In vitro release study of formulation optimized with HPMC : EC (RHE 3) through

Porcine ear skin

Sl. No



Conc in µgm/48 ml

CDR µgm

CDR

µgm/cm2/hr % CDR

1. 1 0.145 6.545455 0 160.3636 160.3636 34.71074 9.449831 2. 2 0.169 7.636364 6.545455 187.0909 193.6364 41.91263 11.41051 3. 3 0.233 10.54545 14.18182 258.3636 272.5455 58.99252 16.06043 4. 4 0.277 12.54545 24.72727 307.3636 332.0909 71.88115 19.56929 5. 5 0.304 13.77273 37.27273 337.4318 374.7045 81.10488 22.08041 6. 6 0.326 14.77273 51.04545 361.9318 412.9773 89.38902 24.33573 7. 7 0.356 16.13636 65.81818 395.3409 461.1591 99.81799 27.17496 8. 8 0.378 17.13636 81.95455 419.8409 501.7955 108.6137 29.56956 9 9 0.421 19.09091 99.09091 467.7273 566.8182 122.6879 33.40119

10 10 0.465 21.09091 118.1818 516.7273 634.9091 137.4262 37.41362 11 11 0.521 23.63636 139.2727 579.0909 718.3636 155.49 42.33139 12 12 0.562 25.5 162.9091 624.75 787.6591 170.489 46.4148 13 24 0.572 25.95455 188.4091 635.8864 824.2955 178.4189 48.57369



Chapter 5 Results


Graph 8: In-vitro permeation profile for optimized formulations RLS 7 and RHE 3 containing 15 mgs of Carvedilol through Porcine ear skin

Chapter 5 Results


Table No 46: Effect of Transdermal drug delivery systems of Carvidilol on mean blood pressure in control and methyl prednisolone acetate (MPA) induced hypertensive rats.

Group Treatment Initial 1 hour 2 hour 4hour 6hour 10hour 12hour

1 Control a 113.8 ±1.639 113.9

±1.122

112.2 ±

0.9058

114.2 ±

1.664

113.0 ±

1.123

112.7 ±

1.332

113.4 ±

1.392

2 MPA Control b 156.6± 1.367 157.2 ±

1.621

155.6

±1.679

157.3

±1.558

156.9 ±

1.2785

157.9 ±

4.3697

155.3±

1.3845

3 ERL:ERS(4:1) c 158.6± 1.3706 154.8 ±

0.3867**

148.6±

1.370***

142.6

±1.6133***

138.6 ±

1.1829***

132.9 ±

1.3603***

126.8 ±

1.7648***

4 ERL:ERS(1:4) c 157.6± 0.3552 155.1±

0.3965*

152.6 ±

1.311***

148.9 ±

1.611***

144.9±

1.139***

139.9 ±

1.613***

135.1 ±

1.395***

5 HPMC:EC(8:2)c 158.6± 1.237 153.2 ±

0.3481***

149.3 ±

1.264***

142.3 ±

1.7252***

139.1 ±

1.3451***

134.8 ±

0.1187***

129.2 ±

1.2740***

6 HPMC:EC(5:5)c 156.5± 1.4561 154.6±

0.6423**

152.9±

1.378***

146.1 ±

0.3408***

141.8 ±

1.369***

135.6 ±

1.838***

132.9 ±

1.3829***

*Mean BP (mm Hg) ± SEM

Chapter 5 Results


aControl Group: Received no treatment.

bToxic Control Group: Received Methyl prednisolone acetate s.c. 20mg/Kg/week for two weeks.

cTreatment Groups: Received Methylprednisolone acetate s.c. 20mg/Kg/week for two weeks followed by

Carvidilol(Drug) loaded Transdermal Patches.

*Significant compared with MPA control (P < 0.05).

Chapter 5 Results


Table 47: Kinetic data of various models applied to release study of best formulations

Zero order First order Matrix Peppas Hixon Crowell

Formulation

Barrier

R k R k R k R k n R k

Best

fit

Model

Dialysis

Memb 0.9232 0.0069 0.9233 -0.0001 0.9961 0.0166 0.9947 0.0149 0.5627 0.9232 0.0000 Matrix

RLS 7

Porcine ear skin

0.9124 0.2468 0.9144 -0.0025 0.9928 0.5961 0.9838 0.6121 0.4780 0.9137 -0.0008 Matrix

RHE 3 Dialysi

s Memb

0.9911 0.8685 0.9927 -0.0089 0.9642 2.0539 0.9969 1.3203 0.7592 0.9922 -0.0029 Peppas

Chapter 5 Results


Porcine ear skin

0.9930 0.3421 0.9928 -0.0035 0.9216 0.7979 0.9655 0.4405 0.8332 0.9929 -0.0011 Zero order

Table 48: Data obtained from stability studies for physico-chemical parameters of optimized patches

Physical appearance Folding Endurance Decrease in weight (gm) Drug content Sl.

No.

Time Interval

RSL 2 RHE 3 RSL 2 RHE 3 RSL 2 RHE 3 RSL 2 RHE 3

1. 0 days + + + + 157 117 0.751 0.638 95.21 98.07

2. 15 days + + + + 158 125 0.747 0.630 93.67 98.69

3. 30 days + + + + 133 105 0.742 0.621 94.37 97.15

4. 60 days + + + 176 98 0.738 0.616 93.55 97.42

5. 90 days + + + 182 90 0.735 0.613 93.70 96.34

Chapter 5 Results


+ + — No change in physical appearance

+ — Slight change in physical appearance.

STABILITY STUDIES » Spectra 17: IR spectra of formulation RSL 2 at 400C ± 20C / 75% RH ± 5% RH

Chapter 5 Results


Chapter 5 Results


STABILITY STUDIES » Spectra 18: IR spectra of formulation RHE 3 at 400C ± 20C / 75% RH ± 5% RH

Chapter-5 Results


5.2 PREFORMULATION STUDIES The following Preformulation studies were performed for Carvedilol.

5.2.1 Melting Point Melting point of Carvedilol was determined by capillary tube method and it

was found to be 115.15 ± 1.5337 (n = 3). This value is same as that of the literature

citation.

5.2.2 Partition Coefficient Partition coefficient determination study of Carvedilol was done with n-

octanol and water. The logarithmic value of partition coefficient (log pka) of

Carvedilol was found to be 3.415. This indicates that Carvedilol is lipophillic in

nature.

Table 10: Data of various Preformulation studies

Sl. no. Drug Melting point

Mean ± S.D.*

Partition coefficient

(Log p)

1. Carvedilol 115.15 ± 1.5337 0.59

*Standard deviation, n = 3

Chapter 5 Results

Table 11: Data obtained from in-vitro flux study of Carvedilol through Porcine ear skin

Sl. No

Time in

Hours Absorbance

Conc. in µg/5 ml

(with dilution)

Conc. in µg/1 ml

(Conc x D.F)

Conc. in µg/48 ml

CDR µgm

CDR µg/cm2/hr

% CDR

1. 1 0.191 8.63 0 211.59 211.59 45.79 12.46 2. 2 0.212 9.59 8.63 234.97 243.61 52.73 14.35 3. 3 0.265 12 18.22 294 312.22 67.58 18.39 4. 4 0.321 14.54 30.22 356.36 386.59 83.67 22.78 5. 5 0.375 17 44.77 416.5 461.27 99.84 27.18 6. 6 0.401 18.18 61.77 445.45 507.22 109.78 29.88 7. 7 0.431 19.54 79.95 478.86 558.81 120.95 32.92 8. 8 0.463 21 99.5 514.5 614 132.90 36.18 9. 9 0.498 22.59 120.5 553.47 673.97 145.88 39.715 10 10 0.536 24.31 143.0909 595.79 738.88 159.93 43.54 11 11 0.578 26.22 167.40 642.56 809.97 175.31 47.72 12 12 0.634 28.77 193.63 704.93 898.56 194.49 52.95 13 24 0.689 31.27 222.40 766.18 988.59 213.98 58.25

The concentration of drug at the donor compartment was: 5 mgs.

Steady state flux through Porcine ear skin was = 9.088 µgm/cm2/hr Kp = 0.001817.

Dept of Pharmaceutics, KLES’s COP, Hubli 88

Chapter 5 Results

Graph 2: Flux of Carvedilol through Porcine ear skin

Dept of Pharmaceutics, KLES’s COP, Hubli 89

Chapter 7 Conclusion

7.0 CONCLUSION

From the above experimental results it can be reasonably concluded that:

The formulated TDD patches of both Eudragit and HPMC-Ethyl cellulose series showed

good physical properties.

18% w/w of TEC and 25% w/w of DBP were suitable plasticizers for Eudragit and

HPMC:EC combinations respectively.

All the optimized patches formulated were stable at room temperature.

FTIR and DSC studies indicated compatibility between the drug and the excipients employed

in the fabrication of TDDS, which was further confirmed by accelerated stability studies as

per ICH guidelines.

SEM micrographs (HPMC:EC, RHE 3) revealed the rough & porous surface nature of the

patches.

Formulated patches did not show any skin irritation reaction as compared to standard.

In Eudragit series, RLS 2 showed highest release (79.70 %) and in case of HPMC:EC series a

maximum of 65.63 % release was obtained for RHE 3 during in vitro drug permeation

studies through dialysis membrane.

The release of Carvedilol appears to be dependent on lipophilicity of the matrix. Moderately

lipophilic matrices showed best release. The predominant release mechanism of drug through

the fabricated matrices was believed to be by diffusion mechanism.

The in vitro release study between dialysis membrane and porcine skin could not be

correlated because of difference in release behaviour.


The in vivo release study the groups 3 (RSL 2), and 5 (RHE 3) were showed significant fall

in BP compared to groups 4(RSL 8) and 6(RHE 7).

170

Chapter 8 Summary

8.0 SUMMARY

Introduction

Transdermal drug delivery systems (TDDS) are adhesive drug containing devices of

defined surface area that delivers predetermined amount of drug to the intact skin at a

preprogrammed rate. The transdermal delivery has gained importance in recent years. The

transdermal drug delivery system has potential advantages of avoiding hepatic first pass

metabolism, maintaining constant blood levels for longer period of time resulting in a

reduction of dosing frequency, improved bioavailability, decreased gastrointestinal irritation

that occur due to local contact with gastric mucosa, and improved patient compliance. Some

of the anti hypertensive drugs already have been formulated and evaluated as transdermal

patches but most of them still been unexplored. Transdermal formulation of anti

hypertensive drug is promising aspect in near future. A few anti hypertensive drugs like

pinacidil, timolol, bupranolol, propranolol, verapamil, nifedipine, metoprolol have been

incorporated in transdermal dosage form and been evaluated.

Objectives

In the present study transdermal films of the carvedilol were prepared using

polymers like Eudragit RS100, Eudragit RL100, hydroxypropylmethyl cellulose and Ethyl

cellulose in different ratios. These transdermal films will be characterized for their

physicochemical properties including drug release.

Industrial Pharmacy, B.P.C., Davangere

171

Chapter 8 Summary

Review of Literature

The chapter ‘Literature Review’ contained the general concepts of transdermal drug

delivery and its applications. Advantages and limitations of drug delivery through

transdermal route were listed. Description of the physiology of skin for drug delivery was

explained. Factors affecting transdermal drug delivery system and possible routes for drug

transport across the skin layer were discussed. Basic components and modern approaches of

transdermal drug delivery systems were described.

Methodology

At the outset, method for estimation of the drug was developed. Carvedilol showed

maximum absorption at wavelength 242 nm in 30% v/v Methanolic isotonic phosphate

buffer (MIPB) pH 7.4. Standard calibration curve obeyed Beer’s law at given concentration

range of 2µg/ml to 20 µg/ml which one subjected to regression analysis.

The value of regression coefficient was found to be 0.998, which showed linear

relationship between concentration and absorbance. The FT-IR peak of carvedilol displayed

some parent peaks at 400 to 4000 cm-1nm. The physical mixture of drug with selected

polymers gave peak which corresponded to the parent peaks of the pure drug which

confirmed the compatibility between drug and selected polymers.


The various formulations of films were developed for carvedilol, dose in given area

of 64 cm2 was 25 mg using various bioadhesive and film forming polymers like Eudragit

RS100, Eudragit RL100, hydroxypropylmethyl cellulose and Ethyl cellulose in different

172

Chapter 8 Summary

ratios by solvent casting method with the incorporation of Tri ethyl citrate and Dibutyl

phthalate as plasticizer.

Physicochemical parameters such as Physical appearance, folding endurance, weight

uniformity, thickness uniformity, Drug content, tensile strength determination, Percentage

moisture uptake, Percentage moisture content, and Water vapour transmission studies were

carried out. In order to know the pattern of release of carvedilol from patches, in vitro

release and skin permeation studies were carried out with dissolution apparatus and

diffusion cell using 30% v/v Methanolic isotonic phosphate buffer (MIPB) pH 7.4 as

receptor medium,

In the present study a total of 14 formulations were formulated and subjected to various

in-vitro evaluation parameters such as Tensile strength, % elongation, % moisture

transmission, % moisture uptake and Drug content, skin irritation test, SEM analysis, XRD

studies, accelerated stability studies as per ICH guidelines, drug-polymer interaction by

FTIR and DSC studies,

In-vitro release study was performed using Keshary-Chein diffusion cell with Himedia

dialysis membrane and porcine ear skin as barriers.

In-vivo method for measurement of systolic BP in Rats.

Short-term stability studies were conducted.

Results and Discussion


The results and discussion obtained from different methods of this thesis were described

under different tables and graphs. From the results of the drug content determination, it was

173

Chapter 8 Summary

inferred that there was proper distribution of drug in the films and the deviations were

within the acceptable limits. Films exhibited higher tensile strength as the concentration of

HPMC was increased. The prepared film exhibited satisfactory physical characteristics such

as weight uniformity, thickness uniformity, and folding endurance. Results revealed that

prepared patches showed good physical characteristics, no drug-polymer interaction and no

skin irritation as compared to standard.

X-Ray Diffraction studies indicated that Carvedilol was not crystalline in both Eudragit

and HPMC:Ethyl Cellulose polymer matrix.

The in-vitro release study through dialysis membrane revealed that formulations RHE 4

and RLS 1 showed maximum release.

The release kinetics of formulations RHE 4 and RLS 1 shows a good correlation value

of zero order model.

In the In-vivo studies, In Eudragit combinations the RLS 1 formulation was most

effective in the reduction of systolic BP (157.8 ± 0.6145 mm Hg to 129.3 ± 0.7398 mm

Hg). In case of HPMC:EC combinations the RHE 4 formulation was most effective in

the reduction of systolic BP (157.8 ± 0.6145 mm Hg to 127.9 ± 0.9940mm Hg).

Formulations RLS 1 and RHE 4 were subjected for accelerated stability studies. Both

formulations were found to be stable as there was no drastic change in the physico-

chemical properties of the patches, which was also confirmed by FTIR.


Thus conclusion can be made that stable transdermal patches of Carvedilol has

been developed.

174

Chapter 8 Summary

Future prospects:

In-vitro skin permeation study using porcine ear or human cadaver skin containing a

suitable penetration enhancer.

Preclinical and clinical studies of the developed formulation can be carried out.

Pharmacokinetic evaluation studies of the developed formulations can be carried out.

Conclusion

From the results obtained and discussion generated there from, encouraged

conclusions were drawn and written in chapter. On the basis of the in vitro characterization

it was concluded that carvedilol could be administered transdermally through matrix type

TDDS developed in our laboratory. Transdermal patches consisting of the rate-controlling

polymer Eudragit RS100, Eudragit RL100 and polymer HPMC, EC demonstrated sustained

and controlled release of the drug across rat abdominal skin during in vitro permeation and

in vivo studies. The drug remained intact and stable in the TDDS during storage, with no

significant chemical interaction between the drug and the excipient. Further work is to

establish the therapeutic utility of this system by pharmacokinetics and pharmacodynamic

studies on human beings.


175

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Chapter 10 Annexures

K.L.E.S s College of Pharmacy, Hubli 188

Chapter 10 Annexures

K.L.E.S s College of Pharmacy, Hubli 189

Master of Pharmacy in Pharmaceutics

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