Studies on the bioequivalence of different strengths of tablets containing clarithromycin.

The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of clarithromycin (CAS 81103-11-9) tablets (Klaromin, test tablets) containing 250 mg (study 1) or 500 mg (study 2) of the drug with reference tablets of the same strength. Each study was conducted according to an open, randomized, single-dose, two-period crossover design in healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 24 h in both studies, and concentrations of clarithromycin and its principal active 14-hydroxy metabolite were determined by HPLC method. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of clarithromycin were between 0.93 and 1.05 (AUC0-t) as well as between 0.90 and 1.18 (Cmax). In the second study, i.e. after administration of clarithromycin 500 mg tablets, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of clarithromycin were between 0.90 and 1.08 (AUC0-t) as well as between 0.85 and 1.22 (Cmax). All these values were within the acceptance ranges for bioequivalence studies. In both studies, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of 14-hydroxy-clarithromycin were also within the acceptance ranges, although the confidence intervals for these parameters were not planned to be compared with the acceptance ranges. In the light of the results of the studies reported here it can be concluded that the clarithromycin 250 mg and 500 mg test tablets are bioequivalent to the respective reference formulations.