To determine bioequivalence of a generic 10 mg montelukast tablet formulation. A 2-period, 2- sequence crossover study was designed. It included 28 healthy subjects, each subject received a single dose of the randomly assigned formulation with 240 ml water after 10-hr fasting, and 14 blood samples (6 mL each) were drawn at predose, and 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 7, 10, 12 and 24 hr post-dose. The procedure was repeated after a 7-day washout period. Plasma samples were stored at -20°C until analysed using LC-MS/MS, LLOQ 5 ng/mL. The mean ± SD for the test and the reference were: Cmax 568±185 and 570±205 ng/mL; and AUC0-” 3864±1228 and 4022±1331 ng.hr/mL, respectively. The log-transformed ratios (90% CI) were: Cmax : 99.64% (92.80% - 109.66%); and AUC0-∞ : 99.79 (92.25% - 102.37%). The two formulations were bioequivalent as the 90% CI for the log-transformed ratios for the mean Cmax , and AUC0-∞ were within the 80-125%.
