Chapter 4 Special Populations Geriatrics Copyright 2013 by

Special Populations: Geriatrics Overview Older adults make up 14% of the population yet account for 30% of medication expenditures Among a national sample of 2950 older adults: Ø Ø 12% took 10 medications daily 23% took 5 prescription medications daily (Frankfort et al. , 2006) Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 2

Special Populations: Geriatrics Overview (Cont. ) Polypharmacy Ø Ø Multiple providers Self-medication: OTC, vitamins, home remedies Risk for ADRs Limited knowledge of impact of specific drugs on older adults Ø Polypharmacy Ø Normal age- and disease-associated changes Ø Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 3

Special Populations: Geriatrics Functional Assessment Core concept Evaluate medications for Ø Ø Ø Efficacy

Special Populations: Geriatrics Functional Assessment (cont. ) Functional Expression: Ø Ø Weight Mobility Continence

Special Populations: Geriatrics Functional Assessment (cont. ) Assessment Tools Ø Ø Katz’s Activities of Daily Living Folstein Mini-Mental Status Examination Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 6

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy Absorption Ø Passively absorbed • Little or no change • Actively absorbed Minimal to no effect on extent of absorption Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 7

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy (cont. ) Distribution Consider common age changes • Decline of total body water • Body mass: lean vs. fat • Decrease in serum albumin Ø Drugs distribution dependent on any of these variables may be affected • Enhanced effect • Toxicity • See Boxes 4 -1 through 4 -3 for common examples Ø Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 8

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy (Cont. ) Biotransformation (Metabolism) Ø Aging influences loss of hepatic reserve: • Declining mass • Decreased hepatic blood flow • Altered nutritional status • Other physiologic changes and diseases Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 9

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy (Cont. ) Biotransformation (metabolism) Phase I metabolism is primarily affected Drugs compete with CYP 450 pathway for metabolism Ø Drugs that are metabolized and excreted by the liver should be started at 30%-40% less than average dose Ø Ø Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 10

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy (Cont. ) Excretion Age-related changes in renal function are most important physiologic factor that results in ADRs Ø Changes include: • Decreased number of nephrons • Decreased renal blood flow, glomerular filtration rate, and Ø tubular secretion rate • Increased number of sclerosed glomeruli • Decreased creatinine clearance Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 11

Special Populations: Geriatrics Pharmacokinetic Changes That Affect Drug Therapy (Cont. ) Excretion (cont’d) Chronic diseases also may affect renal function; this can further complicate required dosing Ø Creatinine clearance • Gold standard: 24 -hour urine collection • Calculation: Modified Cockcroft-Gault equation • Men: Ø Creatinine = Weight (kg*) × (140 – age in years) clearance 72 × Serum creatinine (mg/dl) • Women: Creatinine = Weight (kg*) × (140 – age in years) clearance 72 × Serum creatinine (mg/dl) × 0. 85 Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 12

Special Populations: Geriatrics Pharmacodynamic Changes in the Elderly That May Affect Drug Therapy Receptor affinity or number Hormonal levels Central nervous system Cardiovascular system Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 13

Special Populations: Geriatrics Common Concerns Adverse drug reactions Higher in the older adult Increase exponentially with 4 or more drugs (Jacubeit et al. , 1990) Ø Reduction in number of medications may not be an option Ø The average older adult uses 4. 5 prescription and 2 OTC medications daily Ø Ø Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 14

Special Populations: Geriatrics Common Concerns (Cont. ) Adherence The extent to which a patient follows a planned medical regimen Ø Barriers to adherence: • Cost • Complicated/unrealistic schedules • Impaired cognition/judgment • Side effects • Lack of knowledge related to need or purpose of Ø medication • Fear of side effect or exacerbation of other problems • No perceived response/effect from drug therapy Copyright © 2013 by Mosby, an imprint of Elsevier Inc. 15