Bioequivalence and Pharmacogenetics

The current drug development framework grants the innovator companies the opportunity to market a new drug exclusively for a defined time period under patent protection. After the patent protection period ends, other companies are permitted to produce their own generic version provided they meet bioequivalance. Accordingly, the test compound and the reference compound pharmacokinetic parameters are expected to be within 80% to 125% in terms of Cmax (maximum plasma concentration) and AUC (area under the curve). Generally, bioequivalence trials are carried out in healthy volunteers as a crossover, open, two-way, randomized design where each volunteer takes both test and reference medication in different periods. The remit of a bioequivalence trial is investigating the similarity of test and reference compounds without observing the pharmacodynamics or therapeutic concentration of the medication. If the trial medication has a bioactive metabolite, in this case, both the main molecule and bioactive metabolite should demonstrate bioequivalancy in terms of pharmacokinetic parameters. Both inter- and intra-individual pharmacokinetic variability can be impacted through pharmacogenetic differences and gene expression regulation at an individual and population level. Surprisingly, pharmacogenetics has been considered very little in bioequivalence studies. This expert review article aims to initiate a discussion on the ways in which these two fields of biomedicine offer synergy for innovation, and the ways forward to address the extant challenges at the unique intersection of pharmacogenetics and bioequivalance research and development.