Drug bioavailability in animals: Impact of feeding and nutrition

Abstract

Bioavailability of drugs, though received limited attention, sufficient evidence do exist to suggest that it is significantly influenced by feeds and feed- ing in animals. The nutrient-drug interactions may lead to clinical problems often resulting in adverse drug reactions/toxicity and even nutritional defi ciencies. The complexity and the diversity in the type of interactions within the species, between the species and amongst the drugs warrant the Veterinarians to be more cautious while prescribing the drugs. Concomitant intake of food may al- ter both the role of drug entry and the extent of drug bio-availability. The effects of mineral cat- ions on the course of drug therapy have also been shown to be significant. On the other hand, there exists tremendous ability of selected foods (functional foods) to reduce the risk of diseases and to enhance the quality of life. Inulin and oligofructans alter several biomarkers, including gastrointestinal transit time, colonic, caecal microflora, and even neoplastic conditions. Nutritional effects on drug metabolizing enzymes also have implications for endogenous substances and environmental toxins and carcinogens, which are metabolized by the same or related enzyme systems, and for related diseases. Methods are needed to measure inter-individual and inter-group differences in metabolism of foreign compounds (drugs and pharmaceuticals) in order to accurately assess dietary influences on drug metabolism and vice versa. Lack of sufficient information in this regard in monogastric and polygastric animals and birds necessitates initiating research in Nutritional Pharmacology, particularly with reference to Nutrient-Drug interactions and Drug-Nutrient interactions.