You are working as a Regulatory Affairs specialist at Bayer. The Director of Pro

Question

You are working as a Regulatory Affairs specialist at Bayer. The Director of Product Development comes to you seeking your advice about pursuing a FDA biowaiver (background info for biowaiver provided below) for their Nifedipine products. Nifedipine (shown in the figure) is a dihydropyridine calcium channel blocker used to treat hypertension. Bayer has both a 10 mg immediate-release capsule (Nifedipine Immediate) taken three times a day, and a 30 mg sustained-release version (Nifedipine Sustained-release) taken once daily. The aqueous solubility of Nifedipine is 0.006 mg/mL at pH 7 and it has an octanol/water partition coefficient of 10,000. The absolute bioavailability is 45-75 % for Nifedipine Immediate and 84-89 % for Nifedipine Sustained-Release. What is your advice to the director, and why (Please limit your answer to 300 words)

Explanation / Answer

Nifedipine is BCS class II drug (low solubility, high permeability)

Hence its bioavailability is limited by its solvation rate.

For immediate release formulation of nifedipine, it is of utmost importance that the nifedipine gets dissolved(solubilized) then only it will have proper bioavailability profile. For these in-vivo bioavailability and in-vitro dissolution correlation profile needs to be established. For that biowaiver can not be granted.

While for sustained release formulation of nifedipine the controlled solvation of nifedipine is required only (which is already present for nifedipine as class II drug), hence there will be no need to establish correlation between in-vivo bioavailability and in-vitro salvation rate. Hence the biowaiver for sustained release formulation of nifedine can be granted.

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