Relative bioavailability and pharmacokinetics of two oral nifedipine sustained -release capsules in Chinese volunteers after single dose administration

OBJECTIVE The relative bioavailability between a China made and Ethypharm SA nifedipine oral sustained release capsules (20 mg),and the pharmacokinetics were studied in 12 male Chinese healthy volunteers.METHODS The study was conducted in a two treatment,two period,two sequence randomized cross over trial.The plasma concentration of nifedipine after an oral single dose in the subjects was determined with an electron capture detecting high resolution capillary column gas chromatographic method with nimodipine as the internal standard and ether-0.2 mol·L -1 NaOH cyclohexane (1.5∶1.0∶3.5 ml) as the extraction solvent.The important pharmacokinetic parameters were calculated with non compartment method.RESULTS From the plasma concentration time data of both preparations in the single dose study,the AUC 0～∞ ,c max ,t max and t 1/2 for China made and Ethypoharm SA nifedipine sustained release capsules were (464.8±169.1) and (462.2±152.1) ng·h·ml -1 ,(39.7±9.1) and (41.4±9.1) ng·ml -1 ,(2.6±0.6) and (3.4±1.3) h,(10.4±4.0) and (10.1±4.4) h,respectively.And adequate ANOVA analyses showed that there were no significant difference (α=0.05) between them.The relative bioavailability of the sustained release capsules was (101.0±12.2)%.CONCLUSION The China made nifedipine sustained release capsules was able to maintain the plasma concentration above the effective level for about 12 hours after a single dose.And there was no significant difference between the two preparations with two one sided hypotheses at the α=0.05 level of significance.