Pharmacokinetic properties and bioequivalence of two irbesartan/hydrochlorothiazide fixed-dose combination tablets in healthy male Chinese volunteers

Objectives: The aim of the present study was to compare the pharmacokinetic profiles between a new generic and a branded reference formulation of irbesartan/hydrochlorothiazide FDC tablets, and to assess the bioequivalence of the two products in healthy Chinese male volunteers. Materials and methods: 24 male healthy volunteers participated in the open-label, single-dose, randomized-sequence, 2-way crossover study. Eligible subjects were randomly assigned (1: 1) to receive a single 300/12.5-mg dose of either the test or reference formulation followed by a 1-week washout. Blood samples were obtained before (0 hours) and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 36, 48, and 72 hours after dosing. Plasma concentrations of irbesartan and hydrochlorothiazide were analyzed by two separate validated liquid chromatography/tandem mass spectrometric (LC-MS/MS) methods. Results: For irbesartan, the 90% confidence intervals (CIs) of AUC(0-t), AUC(0-infinity), and C-max were 103.27 - 116.71%, 105.01 - 121.47%, and 84.15 - 96.88%, respectively. For hydrochlorothiazide, the 90% CIs of AUC(0-t), AUC(0-infinity), and C-max were 96.11 - 109.02%, 95.15 - 107.35%, and 91.66 - 101.40%, respectively. A total of 3 mild AEs were reported in 3 subjects (12.5%). Conclusion: In this study, a single dose (300/12.5-mg) of the test formulation of irbesartan and hydrochlorothiazide FDC tablet in fasting healthy Chinese male volunteers met WHO's and China's FDA regulatory criteria for assumption of bioequivalence to the reference formulation based on AUC and C-max. Both formulations were well tolerated.