Two different drugs or two different formulations of the same drug are called bioequivalent if they are absorbed into the blood and became available at the drug action site at about the same rate and concentration. Bioequivalence trials aim to demonstrate that two different drugs or two diferent formulations of the same drug do not differ by more than a prespecified clinically irrelevant amount. In bioequivalence studies, C_max(maximum concentration) and A∪C(area under the blood level curve) serve as the primary pharmacokinetic characteristics of absorption.
We explain in this paper equivalence tests of ration hypothesis under the assumption that the distributions of C_max and A∪C data are log-normal or normal. We compare sample size determination of three bioequivalence tests of Schuirmann(1981, 1987), Anderson and Hauck(1983) and Sasabuchi(1980, 1988). We present more simple approach of sample size determination of Sasabuchi(1980, 1988).
When the original data are log-normally distributed, sample sizes determined by Schuirmann´s and Anderson and Hauck´s test are similar if the difference of the two location parameters becomes small. When the original data are normally distributed, sample sizes determined by Sasabuchi´s test and Schuirmann´s test is smallest among all if the ratio of two population means is, respectively, less than and greater than unity. There is no sample size difference between the method suggested in this paper which is based on Sasabuchi´s test and Hauschke´s one.
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