An Overview of Bioavailability and Bioequivalence Study in Human Subject

Abstract

Currently drug bioavailability has become a subject of interest not only in drug development, but also in the early stages of drug discovery. This is on sequence of the finding that most of the drugs candidate that failed in clinical trials did so because of problems with ADME (absorption, distribution, metabolism, excretion) and toxicology, rather than through lack of efficacy. Efforts are being made in the pharmaceutical industry to improve success rates by taking into account ADME and toxicology aspects in drug discovery from very early one. Therefore, it is not surprising to see that the number of publications on drug bioavailability has been increasing steadily for some time. In this review, attention is focused to briefly discuss some terms of bioavailability, relative bioavailability, bioequivalence, formulation and manufacturing variables that could influence the bioavailability of a drug product, physiologic and other factors affecting bioavailability, characteristics of drugs with the greater potential for a bioavailability problem, assessment of bioavailability from pharmacologic as well as therapeutic response, bioavailability of drugs versus dietary supplements, causes of low bioavailability and different approaches to improve it based on biopharmaceutical classification system. Thus approaches to improve drug solubility as well as drug permeability are the important strategies in order to enhance the bioavailability of drugs.