Bioequivalence and Bioavailability Forum

Dear Ioanam!

❝ there is any explanation to use Tmax to predict site of absorption of a drug?

t_max is a rather primitive metric used only in NCA of BE.

❝ Because I don't consider that only this parameter offers me information regarding a gastric or intestinal absorption.

Remember that t_max is not a model parameter in PK, but a derived one - depending on both absorption, distribution, elimination, etc. Imagine a gastric-resistant formulation of the weak acid diclofenac. There's no absorption window for this drug - it will be absorbed in the entire gut. If you see t_max in one subject at 1 h and in another at 16 h, the absorption site most likely is just the same!