TERAPI FARMAKOLOGI TERAPI FARMAKOLOGI PADA GERIATRIPADA GERIATRI

Hal-hal penting pada GeriatriHal-hal penting pada Geriatri Efek umur thd Farmakokinetik dan Efek umur thd Farmakokinetik dan

FarmakodinamikFarmakodinamik Faktor resiko adverse drug events dan Faktor resiko adverse drug events dan

penanganannyapenanganannya Memahami prinsip-prinsip peresepan obat pd orang Memahami prinsip-prinsip peresepan obat pd orang

tuatua Multiple co-morbid stateMultiple co-morbid state PolyfarmasiPolyfarmasi Tingkat kepatuhan minum obatTingkat kepatuhan minum obat Efek fisiologis usia terhadap terapi obat-obatanEfek fisiologis usia terhadap terapi obat-obatan BiayaBiaya

Fakta berkaitan dgn geriatriFakta berkaitan dgn geriatri Pasien berumur 65 th atau lebih Pasien berumur 65 th atau lebih

mencakup 13% dari populasi dan mencakup 13% dari populasi dan membelanjakan 33% obat-obatan yg membelanjakan 33% obat-obatan yg diresepkan.diresepkan.

Tahun 2040, geriatri mencakup 25% Tahun 2040, geriatri mencakup 25% populasi dan membelanjakan 50% obat-populasi dan membelanjakan 50% obat-obat yg diresepkan.obat yg diresepkan.

Pharmacokinetics (PK)Pharmacokinetics (PK) AbsorptionAbsorption

bioavailabilitybioavailability: the fraction of a drug dose reaching the : the fraction of a drug dose reaching the systemic circulationsystemic circulation

DistributionDistribution locations in the body a drug penetrates expressed as locations in the body a drug penetrates expressed as

volume per weight (e.g. L/kg)volume per weight (e.g. L/kg) MetabolismMetabolism

drug conversion to alternate compounds which may be drug conversion to alternate compounds which may be pharmacologically active or inactivepharmacologically active or inactive

EliminationElimination a drug’s final route(s) of exit from the body expressed in a drug’s final route(s) of exit from the body expressed in

terms of half-life or clearanceterms of half-life or clearance

Effects of Aging on Effects of Aging on AbsorptionAbsorption

Rate of absorption may Rate of absorption may be delayedbe delayed Lower peak concentrationLower peak concentration Delayed time to peak Delayed time to peak

concentrationconcentration Overall amount Overall amount

absorbed absorbed (bioavailability) is (bioavailability) is unchangedunchanged

Hepatic First-Pass Hepatic First-Pass MetabolismMetabolism

For drugs with extensive first-pass For drugs with extensive first-pass metabolism, bioavailability may metabolism, bioavailability may increase because less drug is increase because less drug is extracted by the liverextracted by the liver Decreased liver massDecreased liver mass Decreased liver blood flowDecreased liver blood flow

Factors Affecting Factors Affecting AbsorptionAbsorption

Route of administrationRoute of administration What it taken with the drugWhat it taken with the drug

Divalent cations (Ca, Mg, Fe)Divalent cations (Ca, Mg, Fe) Food, enteral feedingsFood, enteral feedings Drugs that influence gastric pHDrugs that influence gastric pH Drugs that promote or delay GI motilityDrugs that promote or delay GI motility

Comorbid conditionsComorbid conditions Increased GI pHIncreased GI pH Decreased gastric emptyingDecreased gastric emptying DysphagiaDysphagia

Effects of Aging on Volume of Effects of Aging on Volume of Distribution (Vd)Distribution (Vd)

Aging EffectAging Effect Vd EffectVd Effect ExamplesExamples body waterbody water Vd for Vd for

hydrophilic hydrophilic drugsdrugs

ethanol, lithiumethanol, lithium

lean body masslean body mass Vd for for Vd for for drugs that bind drugs that bind to muscleto muscle

digoxindigoxin

fat storesfat stores Vd for Vd for lipophilic drugslipophilic drugs

diazepam, trazodonediazepam, trazodone

plasma protein plasma protein (albumin)(albumin)

% of unbound % of unbound or free drug or free drug (active)(active)

diazepam, valproic diazepam, valproic acid, phenytoin, acid, phenytoin, warfarinwarfarin

plasma protein plasma protein ((11-acid -acid glycoprotein)glycoprotein)

% of unbound % of unbound or free drug or free drug (active)(active)

quinidine, propranolol, quinidine, propranolol, erythromycin, erythromycin, amitriptylineamitriptyline

Aging Effects on Hepatic Aging Effects on Hepatic MetabolismMetabolism

Metabolic clearance of drugs by the Metabolic clearance of drugs by the liver may be reduced due to:liver may be reduced due to: decreased hepatic blood flowdecreased hepatic blood flow decreased liver size and massdecreased liver size and mass

ExamplesExamples: morphine, meperidine, : morphine, meperidine, metoprolol, propranolol, verapamil, metoprolol, propranolol, verapamil, amitryptyline, nortriptylineamitryptyline, nortriptyline

Metabolic PathwaysMetabolic PathwaysPathwayPathway EffectEffect ExamplesExamplesPhase IPhase I: oxidation, : oxidation, hydroxylation, hydroxylation, dealkylation, dealkylation, reductionreduction

Conversion to Conversion to metabolites of metabolites of lesser, equal, or lesser, equal, or greatergreater

diazepam, diazepam, quinidine, quinidine, piroxicam, piroxicam, theophyllinetheophylline

Phase IIPhase II: : glucuronidation, glucuronidation, conjugation, or conjugation, or acetylationacetylation

Conversion to Conversion to inactive inactive metabolitesmetabolites

lorazepam, lorazepam, oxazepam, oxazepam, temazepamtemazepam

** NOTE: Medications undergoing Phase II hepatic metabolism are generally preferred in the elderly due to inactive metabolites (no accumulation)

Other Factors Affecting Drug Other Factors Affecting Drug MetabolismMetabolism

GenderGender Comorbid conditionsComorbid conditions SmokingSmoking DietDiet Drug interactionsDrug interactions RaceRace FrailtyFrailty

Concepts in Drug Concepts in Drug EliminationElimination

Half-lifeHalf-life time for serum concentration of drug to time for serum concentration of drug to

decline by 50% (expressed in hours)decline by 50% (expressed in hours) ClearanceClearance

volume of serum from which the drug is volume of serum from which the drug is removed per unit of time (mL/min or removed per unit of time (mL/min or L/hr)L/hr)

Reduced elimination Reduced elimination drug drug accumulation and toxicityaccumulation and toxicity

Effects of Aging on the Effects of Aging on the KidneyKidney

Decreased kidney sizeDecreased kidney size Decreased renal blood flowDecreased renal blood flow Decreased number of functional nephronsDecreased number of functional nephrons Decreased tubular secretionDecreased tubular secretion Result: Result: glomerular filtration rate (GFR) glomerular filtration rate (GFR) Decreased drug clearanceDecreased drug clearance: atenolol, : atenolol,

gabapentin, H2 blockers, digoxin, gabapentin, H2 blockers, digoxin, allopurinol, quinolonesallopurinol, quinolones

Estimating GFR in the Estimating GFR in the ElderlyElderly

Creatinine clearance (CrCl) is used to Creatinine clearance (CrCl) is used to estimate glomerular rateestimate glomerular rate

Serum creatinine alone not accurate in Serum creatinine alone not accurate in the elderlythe elderly lean body mass lean body mass lower creatinine lower creatinine

productionproduction glomerular filtration rateglomerular filtration rate

Serum creatinine stays in normal range, Serum creatinine stays in normal range, masking change in creatinine clearancemasking change in creatinine clearance

Determining Creatinine Determining Creatinine ClearanceClearance

MeasureMeasure Time consumingTime consuming Requires 24 hr urine collectionRequires 24 hr urine collection

EstimateEstimate Cockroft Gault equationCockroft Gault equation

(IBW in kg) x (140-age)(IBW in kg) x (140-age)------------------------------ x (0.85 for females)------------------------------ x (0.85 for females) 72 x (Scr in mg/dL)72 x (Scr in mg/dL)

Example: Creatinine Example: Creatinine Clearance vs. Age in a Clearance vs. Age in a

5’5”, 55 kg Woman5’5”, 55 kg Woman

30301.11.19090

41411.11.17070

53531.11.15050

65651.11.13030

CrClCrClScrScrAgeAge

Pharmacodynamics (PD)Pharmacodynamics (PD) Definition: the time course and intensity of Definition: the time course and intensity of

pharmacologic effect of a drugpharmacologic effect of a drug Age-related changes:Age-related changes:

sensitivity to sedation and psychomotor sensitivity to sedation and psychomotor impairment with impairment with benzodiazepinesbenzodiazepines

level and duration of pain relief with level and duration of pain relief with narcotic narcotic agentsagents

drowsiness and lateral sway with drowsiness and lateral sway with alcoholalcohol HR response to HR response to beta-blockersbeta-blockers sensitivity to sensitivity to anti-cholinergic agentsanti-cholinergic agents cardiac sensitivity to cardiac sensitivity to digoxindigoxin

PK and PD SummaryPK and PD Summary PK and PD changes generally result in PK and PD changes generally result in

decreased clearance and increased decreased clearance and increased sensitivity to medications in older adultssensitivity to medications in older adults

Use of lower doses, longer intervals, Use of lower doses, longer intervals, slower titration are helpful in slower titration are helpful in decreasing the risk of drug intolerance decreasing the risk of drug intolerance and toxicityand toxicity

Careful monitoring is necessary to Careful monitoring is necessary to ensure successful outcomesensure successful outcomes

Optimal Optimal PharmacotherapyPharmacotherapy

Balance between overprescribing and Balance between overprescribing and underprescribingunderprescribing Correct drugCorrect drug Correct doseCorrect dose Targets appropriate conditionTargets appropriate condition Is appropriate for the patientIs appropriate for the patient

Avoid “a pill for every ill”Avoid “a pill for every ill”Always consider non-pharmacologic Always consider non-pharmacologic

therapytherapy

Consequences of Consequences of OverprescribingOverprescribing

Adverse drug events (ADEs)Adverse drug events (ADEs) Drug interactionsDrug interactions Duplication of drug therapyDuplication of drug therapy Decreased quality of lifeDecreased quality of life Unnecessary costUnnecessary cost Medication non-adherenceMedication non-adherence

Adverse Drug Events Adverse Drug Events (ADEs)(ADEs)

Responsible for 5-28% of Responsible for 5-28% of acute geriatric hospital acute geriatric hospital admissionsadmissions

Greater than 95% of ADEs Greater than 95% of ADEs in the elderly are in the elderly are considered predictable and considered predictable and approximately 50% are approximately 50% are considered preventableconsidered preventable

Most errors occur at the Most errors occur at the ordering and monitoring ordering and monitoring stagesstages

Most Common Medications Most Common Medications Associated with ADEs in the Associated with ADEs in the

ElderlyElderly Opioid analgesicsOpioid analgesics NSAIDsNSAIDs AnticholinergicsAnticholinergics BenzodiazepinesBenzodiazepines AlsoAlso: cardiovascular agents, CNS : cardiovascular agents, CNS

agents, and musculoskeletal agentsagents, and musculoskeletal agents

Adverse Drug Reaction Risk Factors in Older Outpatients. Am J Ger Pharmacotherapy 2003;1(2):82-89.Adverse Drug Reaction Risk Factors in Older Outpatients. Am J Ger Pharmacotherapy 2003;1(2):82-89.

The Beers CriteriaThe Beers CriteriaHigh Potential for High Potential for Severe ADESevere ADE

High Potential for High Potential for Less Severe ADELess Severe ADE

amitriptylineamitriptylinechlorpropamidechlorpropamidedigoxin >0.125mg/ddigoxin >0.125mg/ddisopyramidedisopyramideGI antispasmodicsGI antispasmodicsmeperidinemeperidinemethyldopamethyldopapentazocinepentazocineticlopidineticlopidine

antihistamines antihistamines diphenhydraminediphenhydraminedipyridamoledipyridamoleergot mesyloidsergot mesyloidsindomethacinindomethacinmuscle relaxantsmuscle relaxants

Patient Risk Factors for Patient Risk Factors for ADEsADEs

PolypharmacyPolypharmacy Multiple co-morbid conditionsMultiple co-morbid conditions Prior adverse drug eventPrior adverse drug event Low body weight or body mass indexLow body weight or body mass index Age > 85 yearsAge > 85 years Estimated CrCl <50 mL/minEstimated CrCl <50 mL/min

Drug-Drug Interactions Drug-Drug Interactions (DDIs)(DDIs)

May lead to adverse drug eventsMay lead to adverse drug events Likelihood Likelihood as number of medications as number of medications Most common DDIs:Most common DDIs:

cardiovascular drugscardiovascular drugs psychotropic drugspsychotropic drugs

Most common drug interaction effects:Most common drug interaction effects: confusion confusion cognitive impairmentcognitive impairment hypotensionhypotension acute renal failureacute renal failure

Concepts in Drug-Drug Concepts in Drug-Drug InteractionsInteractions

Absorption may be Absorption may be or or Drugs with similar effects can result Drugs with similar effects can result

additive effectsadditive effects Drugs with opposite effects can Drugs with opposite effects can

antagonize each otherantagonize each other Drug metabolism may be inhibited Drug metabolism may be inhibited

or inducedor induced

Common Drug-Drug Common Drug-Drug InteractionsInteractions

CombinationCombination RiskRiskACE inhibitor + potassiumACE inhibitor + potassium HyperkalemiaHyperkalemiaACE inhibitor + K sparing ACE inhibitor + K sparing diureticdiuretic

Hyperkalemia, hypotensionHyperkalemia, hypotension

Digoxin + antiarrhythmicDigoxin + antiarrhythmic Bradycardia, arrhythmiaBradycardia, arrhythmiaDigoxin + diureticDigoxin + diureticAntiarrhythmic + diureticAntiarrhythmic + diuretic

Electrolyte imbalance; Electrolyte imbalance; arrhythmiaarrhythmia

Diuretic + diureticDiuretic + diuretic Electrolyte imbalance; Electrolyte imbalance; dehydrationdehydration

Benzodiazepine + antidepressantBenzodiazepine + antidepressantBenzodiazepine + antipsychoticBenzodiazepine + antipsychotic

Sedation; confusion; fallsSedation; confusion; falls

CCB/nitrate/vasodilator/diureticCCB/nitrate/vasodilator/diuretic Hypotension Hypotension

Doucet J, Chassagne P, Trivalle C, et al. Drug-drug interactions related to hospital admissions in older adults: a prospective study of 1000 patients. J Am Geriatr Soc 1996;44(9):944-948.

Drug-Disease Drug-Disease InteractionsInteractions

Obesity alters Vd of lipophilic drugsObesity alters Vd of lipophilic drugs Ascites alters Vd of hydrophilic drugsAscites alters Vd of hydrophilic drugs Dementia may Dementia may sensitivity, induce sensitivity, induce

paradoxical reactions to drugs with CNS paradoxical reactions to drugs with CNS or anticholinergic activityor anticholinergic activity

Renal or hepatic impairment may impair Renal or hepatic impairment may impair metabolism and excretions of drugsmetabolism and excretions of drugs

Drugs may exacerbate a medical Drugs may exacerbate a medical conditioncondition

Common Drug-Disease Common Drug-Disease InteractionsInteractions

CombinationCombination RiskRiskNSAIDs + CHFNSAIDs + CHFThiazolidinediones + CHFThiazolidinediones + CHF

Fluid retention; CHF Fluid retention; CHF exacerbationexacerbation

BPH + anticholinergicsBPH + anticholinergics Urinary retentionUrinary retention

CCB + constipationCCB + constipationNarcotics + constipationNarcotics + constipationAnticholinergics + constipationAnticholinergics + constipation

Exacerbation of constipationExacerbation of constipation

Metformin + CHFMetformin + CHF Hypoxia; increased risk of lactic Hypoxia; increased risk of lactic acidosisacidosis

NSAIDs + gastropathyNSAIDs + gastropathy Increased ulcer and bleeding riskIncreased ulcer and bleeding risk

NSAIDs + HTNNSAIDs + HTN Fluid retention; decreased Fluid retention; decreased effectiveness of diureticseffectiveness of diuretics

Principles of Prescribing in Principles of Prescribing in the Elderlythe Elderly

Avoid prescribing prior to diagnosisAvoid prescribing prior to diagnosis Start with a low dose and titrate Start with a low dose and titrate

slowlyslowly Avoid starting 2 agents at the same Avoid starting 2 agents at the same

timetime Reach therapeutic dose before Reach therapeutic dose before

switching or adding agentsswitching or adding agents Consider non-pharmacologic agentsConsider non-pharmacologic agents

Prescribing Prescribing AppropriatelyAppropriately

Determine therapeutic endpoints and plan for Determine therapeutic endpoints and plan for assessmentassessment

Consider risk vs. benefitConsider risk vs. benefit Avoid prescribing to treat side effect of another Avoid prescribing to treat side effect of another

drugdrug Use 1 medication to treat 2 conditionsUse 1 medication to treat 2 conditions Consider drug-drug and drug-disease interactionsConsider drug-drug and drug-disease interactions Use simplest regimen possibleUse simplest regimen possible Adjust doses for renal and hepatic impairmentAdjust doses for renal and hepatic impairment Avoid therapeutic duplicationAvoid therapeutic duplication Use least expensive alternativeUse least expensive alternative

Preventing PolypharmacyPreventing Polypharmacy Review medications regularly and Review medications regularly and

each time a new medication started each time a new medication started or dose is changedor dose is changed

Maintain accurate medication Maintain accurate medication records (include vitamins, OTCs, and records (include vitamins, OTCs, and herbals)herbals)

““Brown-bag”Brown-bag”

Non-AdherenceNon-Adherence Rate may be as high as 50% in the Rate may be as high as 50% in the

elderlyelderly Factors in non-adherenceFactors in non-adherence

Financial, cognitive, or functional statusFinancial, cognitive, or functional status Beliefs and understanding about Beliefs and understanding about

disease and medicationsdisease and medications

Enhancing Medication Enhancing Medication AdherenceAdherence

Avoid newer, more expensive Avoid newer, more expensive medications that are not shown to be medications that are not shown to be superior to less expensive generic superior to less expensive generic alternativesalternatives

Simplify the regimenSimplify the regimen Utilize pill organizers or drug calendarsUtilize pill organizers or drug calendars Educate patient on medication purpose, Educate patient on medication purpose,

benefits, safety, and potential ADEsbenefits, safety, and potential ADEs

SummarySummary Successful pharmacotherapy means Successful pharmacotherapy means

using the correct drug at the correct using the correct drug at the correct dose for the correct indication in an dose for the correct indication in an individual patientindividual patient

Age alters PK and PDAge alters PK and PD ADEs are common among the elderlyADEs are common among the elderly Risk of ADEs can be minimized by Risk of ADEs can be minimized by

appropriate prescribingappropriate prescribing