Food, splanchnic blood flow, and bioavailability of drugs subject to first‐pass metabolism

Abstract

There has been considerable interest in the past fifteen years in determining the influence of food and diet on gastrointestinal drug absorption. Welling 21 has recently presented a comprehensive and critical review of these efforts. In general, food reduces the absorption rate of drugs from the gastrointestinal tract but in most instances has little influence on the extent of absorption. Such an effect is clinically significant for sedative‐hypnotics and for other drugs where a prompt response is desired but is probably of little concern in most other cases. On the other hand, food has been found to substantially reduce the extent of absorption of certain drugs, including many antibiotics. This type of food effect often occurs with drugs with poor permeability characteristics that are incompletely absorbed even by fasting patients. Continual administration of such drugs with meals would result in lower steady‐state drug concentrations in plasma than would be found were the drug to be given under fasting conditions.