CHAPTER 13 - BIOAVAILABILITY TESTING IN MAN: PHARMACOKINETIC CONSIDERATIONS

Abstract

This chapter analyzes pharmacokinetic considerations related to bioavailability testing in man. Usually, bioavailability is determined by comparison with a reference preparation that can be a solution injected intravenously or possibly another pharmaceutical formulation that is known to be well absorbed, for example, a solution taken orally. To determine the bioavailability of drugs, samples will be taken from a location where the drugs exert their therapeutic effect, but this will usually be the general circulation or the urine. For certain drugs, the bioavailability should be determined at other levels—this is the case with locally acting preparations and with substances that act in the gastrointestinal lumen. It is envisaged that the bioavailability tests should set out and make acceptable certain standards. These standards would guarantee, as much as possible, that supposedly equivalent drugs and different batches of the same drug would have similar characteristics concerning their therapeutic effect. The chapter also highlights that bioavailability studies on healthy human volunteers or on cooperating patients should be carried out with the most scrupulous respect for the moral and scientific standards defined by the Helsinki declaration.