Pharmacological Concepts: Geriatric Considerations Margarita Blajeva (Group 35, 2010)

Objectives Describe the main physiological changes that occur with aging Identify factors affecting absorption and distribution with the geriatric client Describe how drugs are metabolized and excreted in the elderly Examine the issues related to drug compliance in the elderly population

Demographics Geriatric population Concerns with Geriatric Pharmacology largest consumers of Rx medications the higher the age, the higher the number of Rx drugs a person takes average usage ~ 3-4 drugs per senior (not uncommon to have 10+ Rx) nature and frequency of adverse drug reactions increase with age Concerns with Geriatric Pharmacology changes in body metabolism drug interactions disease processes changes in lifestyle

Aging Estimated that after 25-30 years of age, CO  by 1% a year Most body organs  in size with age  fewer cells to carry out organ functions Changes the way in which body will cope with metabolic processes – particularly important for pharmacology Pharmacological changes: Drug absorption Drug distribution Drug metabolism Drug excretion

Drug Absorption Changes to intestinal tract: Result: Peak drug level: decreased blood flow reduced absorptive surface area decreased gastric secretions decreased motility Result: SLOWED rate of drug absorption SLOWED rate of drug action Peak drug level: tends to decrease with age same amount of drug will be absorbed but over a longer period of time

Drug Distribution Changes in body composition: Lean body mass (muscle) % decreases Body water % decreases Body fat increases (memory helper: people get weaker, fatter and dryer) Because body fat increases with age Lipid soluble drugs = wider distribution… Lipid soluble drugs: Organs with greater fat (adipose tissue/muscle) will get more than younger adults Organs with lower fat content (liver/kidney) will get less than younger adults  liver & kidney do most of the metabolism and excretion so… = SLOWED elimination = GREATER half life = GREATER duration of action

Drug Distribution Body water change = more drug in less fluid GREATER concentration of drug HIGHER concentration of drug in elderly patient Water soluble drugs: Less bodily fluid to dissolve in Less distribution to organs with high adipose content GREATER concentration of drug in certain organs GREATER pharmacological effects

Drug Metabolism In general… Why? Mixed-function oxidase system RATE of drug metabolism decreases with age …but there is much variability Why? Decreased blood flow to liver (less coming in/fewer resources available) Decreased production of liver enzymes Mixed-function oxidase system Enzymes responsible for oxidizing drugs Tend to be strongly affected by the aging process Drugs that are oxidized (eg. Benzodiazepines) will be metabolized slower…  longer duration of drug action

Drug Excretion Main routes of elimination: Renal & Gastrointestinal “Enterohepatic cycling” Some drugs also are eliminated by travelling through the liver, biliary tract, then intestinal tract Some of these drugs, which undergo enterohepatic cycling, will not be eliminated at a final step but will re-enter circulation  increased half-life & duration

Drug Excretion Renal excretion One of the most greatly impacted systems by aging process Renal function decreases across the board:  glomerular filtration rate (GFR)  creatine clearance What this means for medications that are primarily excreted by renal system:  duration of action  plasma drug concentration pharmacological action Therefore dosage must be reduced accordingly.

Drug Compliance Extremely important issue in elderly… Challenges with elderly compliance Complicated dosing regimens Confusion age related memory loss pathologic processes (Alzheimer’s, dementia, etc.) live alone lack of instructions for drug taking procedures confusion tends to be directly proportional to number of Rx medications taken Presence of unpleasant side effects of drug discourages use “Polypharmacy” = multiple drug prescriptions

Drug Compliance Other considerations: Helping compliance: Understanding and training – compliance may be increased dramatically with thorough instructions about the uses and methodology involved with a given medication Form – patients may have difficulty with certain forms of medications (e.g. swallowing large capsules) Container – may be difficult to open, or difficult to read and understand Helping compliance: Understanding of the how and why: this should be done by physician but often is not Developing easy to follow schedule e.g. Pill A after lunch/ Pill B before bed

Drug Compliance BLISTER PACK!!! A possible solution to patient compliance problems

Summary Demographics & Aging Drug Absorption Drug Distribution Drug Metabolism Drug Excretion Compliance

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