Bioequivalence study of nabumetone tablets in man

A nabumetone tablet in development (NabutonR) was tested for its bioequivalence to the reference tablet (UnitonR). Seventeen healthy Korean male subjects participated in this study. Each subject received a 1-g dose of nabumetone (2 tablets each) in an unbalanced, randomized, two-way crossover investigation. Serum concentrations of 6-methoxy-2-naphthylacetic acid (6-MNA), a major metabolite of nabumetone, were measured over 120 hr interval by a high-performance liquid chromatography. The maximum serum concentration (Cmax) and time to reach the maximum concentration (Tmax) were read directly, but area under the serum concentration time curve from time 0 to 120 hr (AUC) and mean residence time (MRT) of 6-MNA were calculated from the serum 6-MNA concentration-time curves. The serum curves showed multiple peaks of 6-MNA in most subjects, and the Cmax and Tmax were read from the highest serum peaks. Calculated bioavailability parameters for test and reference tablets were 1498.6∶1377.9 μg·hr/ml for AUC; 25.2∶23.1 μg/ml for Cmax; 11.8∶16.4 hr for Tmax and 42.6∶43.8 hr for MRT, respectively. The pairedt-test revealed no significant differences in all the parameters between the two tablets. Analysis of variance (ANOVA) revealed no significant differences between groups and formulations in all the parameters (Cmax, Tmax, AUC and MRT) indicating the crossover design of the experiment was properly performed. But significant differences (p<0.05) between subject/groups and periods were found for all the parameters indicating substantial intersubject and interperiodic variations for these parameters.