Pharmacokinetics properties and bioequiavailability of nifedipine sustained-release tablets after a single dose administration in healthy volunteers

OBJECTIVE To investigate the pharmacokinetics properties and bioequiavailability of nifedipine sustained-release tablets after a single dose administration in healthy volunteers.METHODS The study was designed in a two-treatment, two-period, two-sequence randomized cross-over trial. Nitrendipine was used as the internal standard and the concentrations of nifedipine in plasma were determined by HPLC–APCI-MS method.RESULTS The pharmacokinetics parameters were calculated by DAS(ver 1.0 )program and the bioequivalence were compared. The pharmacokinetics parameters were as follows: C_ max —( 52.9 ± 31.5 )μg·L~ -1 and( 52.1 ± 35.6 )μg·L~ -1 ; T_ max —( 4.1 ± 1.16 )h and( 4.7 ± 1.9 )h; t_ 1/2 —( 6.9 ± 3.5 )h and( 7.7 ± 4.5 )h ; AUC_ 0-36 h —( 410.7 ± 188.1 )μg·h·L~ -1 and ( 440.4 ± 271.7 )μg·h·L~ -1 , AUC_ 0-∞ —( 437.6 ± 206.8 )μg·h·L~ -1 and( 477.9 ± 290.4 )μg·h·L~ -1 for tested and reference preparations, respectively. There were no significant differences(P 0.05 ) in AUC_ 0-t , T_ max , C_ max and t_ 1/2 between two preparations. The relative bioavailability of tested tablets was( 104.4 ± 40.1 )%. CONCLUSION The test and reference preparations are bioequivalent.