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Age Changes
By Sue Henderson
Pharmacokinetics
How body acts on drug:
• Reduced renal function, resulting in
reduced elimination of renally excreted
drugs - toxicity
• Dosages should be reduced in the elderly
(start low go slow)
• Acute illness can lead to rapid decrease in
renal function
Pharmacokinetics cont…
• Water content of aging body decreases
• Fat content increases
Pharmaco-dynamics
• How drugs act on the body
• Changes in drug receptors/target organ
responses - alter sensitivity to effect of
drugs (> CNS effects of benzodiazepines).
• Impairment of secondary compensatory
mechanisms - predispose to adverse
effects (orthostatic hypotension with
diuretics or TCAs).
Poly-pharmacy
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Higher rates of disease in the elderly
Take many drugs
> interactions/adverse effects
Multiple sources (different doctors,
hospitals, OTC, friends)
• Hoarders of meds.
• Medication review to confirm full list of
drugs being taken
Noncompliance
• Unintentional - result confusion,
forgetfulness
• Intentional - to minimise adverse effects or
save money.
Minimising adverse effects
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whenever possible, use non-pharmacological treatments
lowest feasible dose (often less than half usual adult dose)
smallest number of medications/simplest dose regimens
be familiar drug effects in elderly
liquid medications if difficulty in swallowing
Simple verbal/written instructions for every medication
presenting symptoms may be a result of medications (not
old age)
• child-proof containers (also elder proof) avoided
• Regular review chronic - may be possible to stop
medications or reduce dose if renal function declines
• Make sure the carer understands treatment
References
Bochner, F., Rossi, S., Royal Australasian
College of General Practitioners,
Pharmaceutical Society of Australia, &
Australasian Society of Clinical and
Experimental Pharmacologists and
Toxicologists. (2008). Australian medicines
handbook (8th ed.). Adelaide: Australian
Medicines Handbook.