Pharmacology in the Elderly

Pharmacological Challenges in the Elderly Pharmacokinetic changes Pharmacodynamic changes Multiple co-morbidities Polypharmacy More adverse effects Adherence problems/cognition Reduced diagnostic precision Few well designed trials in this population

Pharmacokinetics in the Elderly Absorption: remains relatively unchanged with age Distribution: reduce in body water increase in body fat plasma protein binding Metabolism: reduced hepatic blood flow reduced liver volume

reduced enzymatic activity Excretion: reduced renal blood flow atrophic renal tissue

Pharmacodynamic Changes Changes in drug receptors/target organ

responses - alter sensitivity to effect of drugs (> CNS effects of benzodiazepines) 2nd to neuronal loss

Impairment of secondary compensatory mechanisms - predispose to adverse effects (orthostatic hypotension with diuretics or TCAs).

Co-morbidities Lead to polypharmacy Increased risk of developing adverse events 2nd

to co-morbidities Risk of delirium 2nd to anticholinergic drugs 2nd

to degeneration of cholinergic pathways Increased risk of cerebrovascular events on

some antipsychotics in people with pre-existing cerebrovascular damage (Shah and Shu, 2005)

Polypharmacy Over age 65 people use an average of 8 drugs 1/3 of those has inappropriate use of at least

one drug 10% are likely to have dangerous drug

interaction (Cannon et al., 2006)

Minimising adverse effects whenever possible, use non-pharmacological

treatments Start low, increase slowly, monitor frequently smallest number of medications/simplest dose

regimens be familiar with drug effects in elderly Alternative applications if difficulties

swallowing tablets

Minimizing adverse events cont’d Simple verbal/written instructions for every

medication incl. generic/brand names, dosage, frequency, route and indication to avoid confusion

presenting symptoms may be a result of medications (not old age)

Avoid child-proof containers (also elder proof), use Webster pack or RDNS

Ensure carer understands treatment

Reference Cannon, K.T., Choi, M.M., Zuniga, M.A.

(2006), Potentially inappropriate use in elderly patients receiving home health care: a retrospective data analysis. American Journal of Geriatric Pharmacotherapy, 4(2), 134-143.

Shah, A., Shu, G.H., (2005). A case for judicious use of risperidone and olanzapine in BPSD. International Psychogeriatrics, 17(1), 12-22.