The effect of food on drug bioavailability.

The recent literature concerning interactions between ingested food and orally administered drugs, and the resulting effects on the rate and extent of drug absorption, has been reviewed. As was observed previously (1, 2) food has been shown to have a variable effect on drug absorption, and the observed changes are not entirely predictable from a mechanistic viewpoint. While drug-food interactions are shown to give rise to a variety of effects, the majority of reported interactions give rise to either reduced or delayed drug profiles in the circulation. With some drugs such as nitrofurantoin, doxycycline, and lithium, the presence of food increases clinical efficacy by reducing the incidence of local GI side effects. While there appear to be no reports of increases or decreases in the actual therapeutic efficacy of drugs due to food, the frequency of food related changes in drug bioavailability, and the magnitude of some of the effects, suggests that observed changes in drug absorption are likely to have profound clinical consequences particularly with drugs that have low therapeutic indices, steep dose-response curves, or clearly defined therapeutic or toxic levels in the body. The review provides further evidence of the need for greater control in the relationship between drug administration and food ingestion.