Abstract
The equivalencies of generic drugs are assessed by biological equivalency tests. These tests are conducted on healthy subjects by the crossover method in comparison with the original product, which makes them a useful method for comparing bioequivalencies among generics. However, since a large variation in the results is sometimes observed, we decided to determine what causes this.
We requested 28 companies to provide biological equivalency test results for pravastatin sodium tablet (23 products) and compared pharmacokinetic parameters among them. There was a large variation in pharmacokinetic parameters, especially in maximum serum drug concentration, area under the serum concentration to time curve and elimination half-life, though there were no differences between the original product and generic product in each test.
On comparing individual parameters from two tests that were carried out according to nearly the same protocol, there was a marked difference in the distribution of data among subjects, indicating that this was a factor causing parameter differences between tests. Thus, when pharmacists are thinking of using a generic drug, it is important for them to notonly consider average parameter values but also the process by which these values have been obtained.
