Bioequivalence and Bioavailability Forum

Hi PVRC,

❝ […] the agency …

May I ask: Which agency?

❝ … recommend to demonstrate comparative PK in the absence of bioequivalence.

Do I get you right: The study was planned to demonstrate BE, failed, and now you were asked about ‘comparative PK’? I never came across such a term.

❝ The question is that whether all bioequivalence criteria (like 80-125%, group effect etc.,) are still applicable to demonstrate comparative PK.

PK means commonly modeling, which is not acceptable in BE (only NCA). That’s for good reasons (results depend on the chosen model, software/version, initial estimates, parameter constraints, convergence criteria, PopPK or two-stage approach, ). Hence, the outcome is not necessarily reproducible.
When you decide to dive into this murky water, you will be surprised. Even for a simple one-compartment model I bet you will get a huge variability in the absorption rate constant. IMHO, 80–125% will practically never work.