Drug Interactions in Geriatric Patients

Abstract

It has long been recognized that the incidence of adverse drug reactions increases with age (Seidl et al. 1966; Hurwitz 1969). Moreover, the more drugs being taken, the greater the likelihood of an adverse reaction (Williamson and Chopin 1980; Williamson 1984). It was suggested in the report of a Working Party of the Royal College of Physicians of London (1984) on “Medication for the Elderly” that the incidence of adverse drug reactions was the direct result of disproportionate prescribing. Indeed, 80% of the subjects studied by Williamson (1984) were taking prescribed drugs. These were people being admitted to hospital. However, elderly people living at home have a similar pattern, for in a random sample Moir and Dingwall-Fordyce (1980) found that 56% were taking one to three preparations, 15% had four or more, and only 28% had no prescribed medication. Our own findings in Southampton (Table 1) are similar, for in a randomly selected sample of elderly living at home, 61% were taking one to three preparations, 19% four or more, and 20% none. Our sample, however, was structured to contain a larger proportion of elderly (aged 75 years or more) (Table 2), and we also included self- prescribed drugs in our analysis.