Download Pharmacological Concepts: Pediatric and Geriatric Considerations

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
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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:
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Drug absorption
Drug distribution
Drug metabolism
Drug excretion
Drug Absorption
• Changes to intestinal tract:
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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:
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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
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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