Pharmacological Concepts: Geriatric Considerations

Margarita Blajeva(Group 35, 2010)

Objectives

1. Describe the main physiological changes that occur with aging

2. Identify factors affecting absorption and distribution with the geriatric client

3. Describe how drugs are metabolized and excreted in the elderly

4. Examine the issues related to drug compliance in the elderly population

Demographics

Geriatric population• 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:• 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…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:• 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!!!

Summary

• Demographics & Aging

• Drug Absorption

• Drug Distribution

• Drug Metabolism

• Drug Excretion

• Compliance

THE END