PHARMACOKINETIC AND BIOEQUIVALENT STUDY OF A GENERIC METOPROLOL TABLET PREPARATION

A study was conducted to compare the in vivo bioavailability of a gene ric metoprolol tablet preparation (Metoprolol(R)) with that of the inn ovator product Betaloc(R). Both preparations have a labeled dose of 10 0 mg metoprolol tartrate. Twelve healthy adult male volunteers partici pated in the study, which was conducted according to a standard two-wa y crossover design with a washout period of I week. The bioavailabilit y was compared using the total area under the plasma level versus time curve (AUC(0-infinity)), peak plasma concentration (C-max), and time to reach peak plasma concentration (T-max). No statistically significa nt difference was observed between the logarithmically transformed AUC (0-infinity) values or the logarithmically transformed C-max values of the two preparations. However, a statistically significant difference was observed between the T-max values, but may not be therapeutically significant or important. Moreover, the 90% confidence interval (CI) for the ratio of the logarithmically transformed AUC(0-infinity) value s of Metoprolol over those of Betaloc was calculated to be between 0.9 4 and 1.02, while that of C-max was between 0.98 and 1.01, both of whi ch are within the acceptable limit of 0.80-1.25. From the data obtaine d, it was also observed that a high proportion of our volunteers of As ian origin appeared to be poor metabolizers of metoprolol, which was c onsistent with what had been observed in our previous study of another preparation of metoprolol.