Age Changes By Sue Henderson Pharmacokinetics How body

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 • • 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 • • 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 (8 th ed. ). Adelaide: Australian Medicines Handbook.