Bioequivalence and Bioavailability Forum

Dear Tushar,

I suppose you're using ivivc for R.

❝ values of absorption constant, elimination and volume of distribution.

❝ Can anybody tell me, based on what conditions we have to select these 3 values?

The elimination rate constant (k_el)and Vd can be obtained from literature or any IV, solution, IR dosage form study. I don't think that it requries you to enter absorption rate constant.

❝ Actually, I have one pilot 2-way crossover bio-study data of ER oral formulation with 6 subjects which shows bioequivalence result (ratio &

With 6 subjects in one pilot to show bioequivalence? Wow!

❝ C.I. are between 80% to 125%) but when I input these data and its dissolution into R software to check IVIVC and its prediction error. It shows prediction error 37% and 41% for Cmax and AUC respectively. which is quite doubtful.

Supposed you have done everything correctly, it is not so surprised at all. It implies that you have a poor ivivc model, although you have proved that THIS formulation is bioequivalent to its brand product. Please note that iviivc for R uses internal validation right now. For external validation, you have to calculate yourself with a spreadhseet (like ms-excel or oo-calc). Or the PK model of your study drug is more complicated, such as more than one-compartment linear or nonlinear PK model. If this is the case, it limits the use of ivivc for R. Here is a nice post for ivivc reference by Helmut.