The FDA should eliminate the ambiguities in the current BCS biowaiver guidance and make public the drugs for which BCS biowaivers have been granted.

Although US Food and Drug Administration (FDA)-approved Biopharmaceutics Classification System (BCS) class 1 drugs are designated as high-permeability drugs, in fact, the criterion utilized is high extent of absorption. This ambiguity should be eliminated, and the FDA criterion should explicitly be stated as > or =90% absorption based on absolute bioavailability or mass balance. Maintaining confidentiality regarding the drugs for which the FDA has approved BCS waivers of in vivo bioequivalence studies is not good public policy and should be reversed.