Evaluation of pharmacokinetics and bioequivalence of indapamide capsules

Objective:To establish a HPLC method for the assessment of pharmacokinetics and bioequivalence of indapamide capsules(test sample) versus indapamide tablets(reference sample).Methods:20 healthy Chinese male volunteers were randomized to orally receive a single crossover dose of test or reference samples(5 mg).The blood concentrations of indapamide from the volunteers at the certain timepoints post the administration were measured by HPLC composed of an Inertsil ODS-3 column,a gradient eluent of phosphate buffer(pH4.0)∶acetinile∶methanol(55∶40∶50) and then methanol only,and a UV detection at 240 nm.The pharmacokinetic parameters as well as relative bioavailability were analyzed based on a non-compartment model,variation analyses and a two-sided t-test.Results:The main pharmacokinetic parameters of indapamide capsules and tablets were as follows: AUC_(048h)(6 193.7±873.5) vs.(6 289.8±899.2) h·ng·mL~(-1),AUC_(0-∞)(7 311.8±1 232.3) vs.(7 529.4±1 323.2) h·ng·mL~(-1),C_(max)(331.1±39.2) vs.(358.4±42.9) ng·mL~(-1),T_(max)(3.2±0.9) vs.(2.7±1.0) h,t_(1/2)(17.2±2.8)vs.(18.3±3.1) h,and MRT(25.0±3.9) vs.(25.8±4.1) h,respectively;the P value of these parameters showed no statistical difference(P0.05).The relative bioavailability of the test to reference was(99.1±11.6)%.Conclusion:The reliable,simple and sensitive HPLC method was applied to evaluate blood indapamide concentrations.The indapamide capsules are bioequivalent to indapamide tablets.