Bioequivalence and Bioavailability Forum

I'm very grateful for your answer! Now everything is in the right place.

❝ Difficult drug to show BE.

That's it! We've got CI for Cmax of about 115-140% that is far from the required. On the other hand CI for AUC0t lies fully in the proper limits. It is our first study with failed BE and I anticipate the sponsor's anger. I have no ideas of what to do: the standardized differences don't afford to exclude subjects.
Another serious problem is inadequate design: we have only 4-5 non-zero points for each subject; I mean that the concentration rapidly rises from zero to Cmax and then goes down, but the majority of the samples that we measure are far from this range (=are BQL). So there are no three nonzero samples after second Tmax... For our case "after a very long, long time" is just about half an hour! (We've got curves similarily to those pointed in the article Upadhyaya V., et al., Determination of mycophenolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry, Journal of Pharmaceutical Analysis 2014; 4(3):205-216)

❝ Yes. It might well be possible that you see in some patients no second peak, the second one smaller than the first one or vice versa. This behavior may even change within the same patient. For a nice PK model see Prémaud et al. (2005).*

All the patients have second peak in the profile of the curve and this peak is significally smaller than the first.
Thank you for the link but full text of the article is not available.
But you claim that PK model is not necessary for standard BE study, am I right?
Are there any official documents (like FDA recommendations or something else) where I can find the statement that half life calculation is incorrect and isn't neccessary in the case when we have lack of information about the terminal phase of the curve?