Bioequivalence and Bioavailability Forum

Dear C_max!

Let’s take magnesium as an extreme example. The body pool is ≈20 g, the daily requirement 300 mg, the plasma concentration ≈25 µg/mL. There are drugs registered to treat Mg-deficiency with strengths of 100–400 mg. Given the daily intake and the large body pool, do you consider it will be possible to distinguish between a 100 and a 200 mg dose – not to speak to be able to detect at 20% difference between formulations? That’s why in the literature oral bioavailabilty could only be demonstrated by ²⁸Mg tracer studies – which is not an option in BE (you can’t modify the formulations). BTW, we tried it in the past (a lot of standardisation, run-in, etc.), but failed terribly after correction for the baseline.