Drug Interactions and Reactions Update

Abstract

Elderly patients take a large number of drugs, especially psychoactive agents, and polypharmacy seems to be the rule in acute hospital settings and in institutions alike. Knowledge about alteration in drug response, with aging, is still at a preliminary and investigational stage, and the problem is compounded by the fact that there are relatively few drugs for which a special geriatric dosage is recommended. It appears to be common practice to keep the elderly in “chemical strait jackets” in some institutions, with emphasis on the use of antipsychotic and sedative/hypnotic combinations. Use of these agents has reached such proportions in Britain and America that it has become necessary to warn that antipsychotic drugs should be used only to treat acute behavior disorders in such patients. The potential for drug-drug interactions in the elderly patient is, therefore, large, and, in the community, the most common categories of prescribed drugs taken by the elderly are psychotropics, diuretics, and antipyretic/analgesics. In addition, analgesics and laxatives are often taken as nonprescribed medicines. Poor compliance with medication instructions, hoarding of drugs, and inadequate knowledge of the purpose of medication are very common. The eventual sequel to these factors is hospitalization; diuretics, hypotensives, antiparkinsonian agents, and psychotropics carry the greatest risk of evoking serious adverse drug reactions. Some specific drugs or groups of drugs present peculiar problems to the aged patient; these agents are relatively few in number and include digoxin, hypotensives, diuretics, nonsteroidal antiinflammatory agents, benzodiazepines, phenothiazines, lithium, and other psychoactive drugs. Currently, lithium and the antirheumatoid agent benoxaprofen are causing much concern in regard to the elderly. With lithium, there are adverse effects suggestive of neurotoxicity, and interactions with concurrent neuroleptic and/or antidepressant therapy, diuretics, and low salt diet are involved. As for benoxaprofen, reports in the past few months have causally linked this drug with fatal cholestatic jaundice and other serious reactions; this drug has now been withdrawn from clinical use. Health professionals must use extreme care when treating an elderly patient with drugs.