Counterintuitive? [Design Issues]

posted by bebac_fan – US, 2018-04-04 00:43 (1343 d 20:39 ago) – Posting: # 18637
Views: 5,193

Hi Nobody,

» Why should the ratio of REL influence the appropriate metric for BE? Switching T and R should not influence the test in my opinion...

The BE studies I have seen (I am quite junior), the drugs follow dose-linearity. One convenient result is that the shape of the PK curve generally stays the same under test conditions. That means the tests aren't required to be sensitive for changes in shape.

This drug doesn't follow that assumption for reasons previously discussed. The PK shape changes under small formulation changes (e.g. REL). There is definitely a need for non traditional parameters, as it is conceivable that AUCinf and Cmax may pass, but with wildly (and clinically relevant) differences in shape.

I agree that the test applied should be invariant to T/R or R/T. Perhaps run a test on Tmax - which based on the above image, appears to be sensitive to changes in REL. Or require passing all the tests together.

Cheers,
BF

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