Older persons consume a disproportionately high quantity of prescription and nonprescription drugs. Thirty-one per cent of all medications are prescribed to patients older than 65 while they comprise less than 12% of the total US population (Lamy, 1980). The high prevalence of chronic illness and elevated use of health-care services among the aged, and socioeconomic factors such as mass media promotion of medication use, to the exclusion of nondrug alternatives, contribute to the increased drug use. Heart disease, hypertension, and arthritis are common chronic conditions that, among others, afflict four out of five aged persons and occur about five times more frequently than in younger age groups (Soldo and Agree, 1988). Physician visits markedly increase with patient age, as do the frequency and total number of medications prescribed per visit (Stewart, 1988).

The ranking of specific drug categories administered to patients over 65 years of age has remained consistent over the years. Table 11.1 lists the most common drug classes identified in two studies of prescription drugs or combined prescription and nonprescription medication use in older persons (Task Force on Prescription of Drugs USDHEW, 1968; May et al., 1982). Most of the top-ranked drug categories are commonly associated with adverse reactions including sexual dysfunction.

Adverse drug effects have been reported two to three times more frequently among the aged than in the general population (Wade and Bowling, 1986). The risk of toxic drug reactions to specific drugs in the elderly requires that altered pharmacokinetics and age-related changes in organ response are considered. (Andrews, 1992).