Assessment of individual and population bioequivalence using the probability that bioavailabilities are similar.

In this paper a new method for the assessment of both individual and population bioequivalence is proposed that is derived from the approach of Schall and Luus (1993, Statistics in Medicine 12, 1109-1124). The method considers the probability that the bioavailability of the test product is close to the bioavailability of the reference product, against the probability that the bioavailability of the reference product is close to itself when administered on different occasions. The method can accommodate unequal variances of the bioavailabilities of the test and reference formulations, as well as formulation by subject interaction. It is thus as general and comprehensive as the methods proposed by Sheiner (1992, Statistics in Medicine 11, 1777-1778) and Schall and Luus (1993), but the resulting bioequivalence criteria are simple and easy to interpret.