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Continuing our BCS topic, this week we will look at biowaivers. A biowaiver means that in vivo bioavailability and/or bioequivalence studies may be waived (not considered necessary for product approval).
For the sponsoring drug company, this means that instead of conducting expensive and time-consuming in vivo studies, a dissolution test can be adopted as the surrogate basis for the decision as to whether or not two pharmaceutical products are equivalent.
Drugs considered for a biowaiver should have high solubility and high permeability according to the BCS. This basically means that BCS Class 1 drugs can be considered. Generally, the drug should be:
- Highly soluble,
- Highly permeable, and
- Rapidly dissolving
Highly soluble means the highest dose strength is soluble in <250 mL of water over a pH range of 1 to 7.5.
Highly permeable means the extent of absorption in humans is determined to be >90% of an administered dose.
Rapidly dissolving is when no less than 85% of the labeled amount of the drug substance dissolves within 30 minutes, using USP Apparatus I at 100 rpm (or Apparatus II at 50 rpm) in a volume of 900 mL or less in each of the media like 0.1 N HCl or Simulated Gastric Fluid USP without enzymes, pH 4.5 buffer, pH 6.8 buffer, or Simulated Intestinal Fluid USP without enzymes.
Next week: More on biowaivers.
Loyd V. Allen, Jr., PhD, RPh
Editor-in-Chief
International Journal of Pharmaceutical Compounding
Remington: The Science and Practice of Pharmacy Twenty-second edition
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