Bioavailability studies of acetaminophen and nitrofurantoin.

264 The Journal of Clinical Pharmacology T HE effects of dosage form variables on therapeutic efficacy and/or bioavailability of drugs are well documented.m Usually, these effects will be manifest principally in differences in rate of absorption and/or differences in efficiency of absorption. Since a formulation which releases a drug slowly over an extended time could have the same bioavailability as a formulation with a more rapid rate of absorption, it is important to commsider both rate and extent of absorption as criteria for assessing therapeutic equivalency. Uwilt et al.2 mmoted differences imm blood and plasma levels of aeetaminophen after administering 1 Gm of drug as whole tablets (eight different manufacturers), as crushed tablets (one manufacturer), and as a tablet containing sorbitol. However, his comparisons were made at a single sampling time (45 minutes after administration). McGilveray et al.3 compared efficiencies and rates of absorption of eight