Drug interactions in the elderly.

Polypharmacy and its dangers in the elderly are of increasing concern. The purpose of this study was to determine the incidence of drug with drug, drug with food, and drug with alcohol interactions in a population aged 60 years or greater. Four hundred patients were randomly selected from a university family medicine outpatient clinic population of 4,483 in this age group. A total of 292 drugs were involved for a total of 1,052 potential interactions: 310 drug-food, 316 drug-alcohol, and 426 drug-drug. Interactions were analyzed using The Drug Master computer program and rated as to their clinical significance. Chart review revealed no serious actual interaction for any patient even though potential interactions could be categorized as highly significant for 27 percent of the drug-drug, 11 percent of the drug-alcohol, and 3 percent of the drug-food. Thirty-two percent of the total population were taking five or more drugs concurrently. The mean number of drugs for men was 3.75 and for women 4.22 (P less than .05). Age and race differences were also noted in the number of drugs taken. The most common drugs and their interactions with drug, food, and alcohol are reviewed.