ABSTRACT
AIM: To study the pharmacokinetics and rela ti ve bioavailability of naftopidil in healthy male volunteers. METHODS: The naftopidil concentrations in plasma were determined by HPLC. The test and reference formulations of naftopidil were given to 18 healthy male volunteer s. The calibration curve was linear within the range of 1.6 - 400 ?g?L -1 , r=1. The minimum detection limit was 1 ?g?L -1 . The mean recovery rate was 85.2 %- 89.9 %, RSDs of inter-day and i ntra-day were no more than 8.0 %. RESULTS: After a single o ral dose of 50 mg naftopidil test capsules or reference tablets, the main pharma cokinetic parameters AUC 0-24 : 295.6 ? 90.9 and 291.6 ? 89.3 ?g?L -1 ?h -1 ; AUC 0-∞ : 320.0 ? 97.2 and 318.0 ? 98.3 ?g?L -1 ?h -1 ; T max : 0.6 ? 0.2 and 0 .6 ? 0.2 h ; C max : 129.1 ? 60.7 and 138.3 ? 72.5 ?g? L -1 ; T 1/2 : 5.9 ? 1.7 and 6.4 ? 2.1 h , respectively. The relative bioavailability F 0-24 ,F 0-∞ were 101.9 ? 12.9 % and 101.2 ? 12.3 %, respectively. CONCLUSION: No signifi cant difference exists among the pharmacokinetic parameters for the test capsule s and the reference tablets of naftopidil. The two formulations were bioequivale nt.