Pharmacokinetics and Bioequivalence Study of Nifedipine Controlled-release Tablets after Multiple Doses Administration in Healthy Volunteers

OBJECTIVE Povidone/Copovidone were used as the main osmopolymers instead of Poly (ethylene oxide) (PEO) to prepare nifedipine controlled-release tablets of new osmotic pump type. The pharmacokinetic properties of nifedipine controlled-release tablets after multiple doses in healthy volunteers were studied, and the relative bioavailability of the test preparation was calculated and the bioequivalence was evaluated. METHODS Twenty four male healthy volunteers were enrolled in a randomized two-way crossover design. 30 mg nifedipine was administered per day during consecutive 7 d. The drug concentration in blood was determined with LC-MS/MS method. The pharmacokinetic parameters, relative bioavailability and the bioequivalence were calculated by DAS program. RESULTS The main pharmacokinetic parameters after multiple doses of test preparation and reference preparation were as follows:T1/2β (9.0±2.2)h and (9.5±3.8)h; Tmax (8.1±7.4)h and (6.7±4.1)h; Cssmax (52.7±28.2)μg·L-1 and (44.5±22.6)μg·L-1; Cssmin (29.4±22.2)μg·L-1 and (28.7±15.8)μg·L-1; AUC0-60 (1 087.4±671.6)μg·L-1·h and (1 040.2±518.4)μg·L-1·h; AUC0-∞ (1 113.1±677.2)μg·L-1·h and (1 074.5±519.8)μg·L-1·h , AUCSS (809.1±454.0)μg·L-1·h and (713.9±382.2)μg·L-1·h. The average relative bioavailability of the test preparation versus the reference preparation was as follows: FAUCss (115.2±29.2)%, FAUC0-60 (103.4±30.2)% and FAUC0-∞ (102.2±29.7)%. DF was (77.84±52.09)% and (55.48±30.54)%. The 90% confidence interval of Cmax, AUC0-60, AUC0-∞ and AUCss after longarithmic transform was (100.9-126.0)%, (87.5-111.8)%, (86.8-110.3)% and (98.8-124.4)% respectively. There was no significant difference in Tmax after non-parameter rank sum test. No adverse reaction was observed during the trial. CONCLUSION The test preparation was bioequivalent to the reference preparation. Povidone/Copovidone could replace PEO used as the main functional excipient of osmotic pump type controlled-release preparations.