Bioequivalence and Bioavailability Forum

Hello Everyone,

I am facing the problem to perform the calculation of in vitro Bio-equivalence of Sevelamer Carbonate.
As per the US FDA guidelines, we have conducted the Kinetic binding study for test and reference at 8 different levels of concentrations of phosphate. Then this binding study is repeated over 12 times.

Now for further data calculation, I have considered these 8 levels of concentration and then calculated K1 and K2 for each study. Same way for 12 repeats.
So eventually I got 12 values of K1 and K2 for test and reference individually.
These K1 and K2 are calculated using Linear Regression in which some of K1 and K2 are negative.
Do negative values exist for K1 and K2?
Which method should I use to calculate 90% CI for ratio of K2?

Thanks in advance

Regards,
Tushar