Bioequivalence and Bioavailability Forum

Dear,

It is very clear in case of drugs which under go very high first pass metabolism and get converted into active metabolites. While performing BE study for such drugs the active metabolite is determined and compared with the innovator formulation during a BE study.

My question is regarding BE studies of drugs which occur in systemic circulation after dosing and their metabolites are also found in circulation at concentrations which can very easily be determined.

1. Is it necessary to determine the concentration of these active metabolites and provide the comparative pharmacokinetic data with all statistical treatments?

2. what is the view that can be found about this issue on various guidances?

3. Can some one provide examples to illustrate this point?
Any views will be highly appreciated.
Thanks a million for the active and inactive (metabolites) oops.. suggestions
USFDA_EMEA.