COMPARATIVE PHARMACOKINETICS OF 2 NIFEDIPINE PRODUCTS IN CAPSULE FORMFOLLOWING SINGLE ORAL-ADMINISTRATION IN HEALTHY-VOLUNTEERS

The pharmacokinetic parameters (AUG, C-max, T-max, and t(1/2)) of nife dipine following single oral administration of a 10 mg capsule of test product were compared to those of the same amount of a reference prod uct. The two products in capsule form were administered according to a randomized two-way crossover design in 22 healthy male volunteers. Ni fedipine plasma concentrations were determined using a rapid, sensitiv e and precise high performance liquid chromatography (HPLC) method wit h ultraviolet (UV) detection at 235 nm. The parametric 90% confidence intervals of the mean value of the ratio [Myogard((R)) (test product)/ Adalat((R)) (reference product)] for pharmacokinetic parameters were 0 .90-1.08, 0.80-1.07, and 0.93-1.12 for AUC(0-->infinity) C-max and t(1 /2), respectively. In each case, values were within the acceptable bio equivalence range of 0.8-1.25. Distribution free point estimate for th e difference in expected medians of T-max of the two products (Myogard ((R))-Adalat((R))) was 0.00 h with a 90% confidence interval of 0.00-0 .13 which is greater than the accepted bioequivalence of +/- 0.12. The kinetic parameters were comparable to those reported for nifedipine, and no statistically significant differences were found in any of them when comparing the two products by analysis of variance (ANOVA) on lo g-transformed data. Thus, the two products could be considered bioequi valent regarding absorption rate (C-max and T-max), extent of absorpti on (C-max and AUG) and elimination (t(1/2)).