Abstract
Anxieties about the quality of generic drugs are one of reasons why these drugs are not generally used in therapies in Japan. To reduce anxieties, we propose a statistical and objective method to evaluate the quality of generic drugs using the coefficient of variances (CVs) calculated from their pharmacokinetic parameters. CVs were estimated from AUC, Cmax, Tmax, t1/2, and MRT, which were provided as publicly-available drug information. The generic drug assessment tool (G-DAT), an original equation derived from the ratio of CVs of corresponding generic to original drugs, and the quality of generic drugs was statistically evaluated. As expected, when evaluated with G-DAT, there was little variance between original and generic drugs using 11 medicines. Antihypertensive dihydropyridines with a lower solubility were shown to have a larger CV. No significant difference in CVs was observed when famotidine and ebastine OD tablets were taken with or without water. G-DAT and the ratio of CVs (CCVs) of generic to original drugs revealed pharmacokinetic equivalences between generic and original drugs. The proposed comparative evaluation showing equivalent pharmacokinetics of generic to original drugs can be used as one solution to reduce anxieties and increase the reliability of generic drugs.
