Pharmacokinetics and bioequivalence study of irbesartan tablets after a single oral dose of 300 mg in healthy Thai volunteers

Pharmacokinetics and bioequivalence of 300 mg irbesartan tablets were studied in 26 healthy Thai male volunteers.A single oral dose of one 300 mg tablet of the test product and the reference product was given to each volunteer according to a randomized two-way crossover design with 1-week wash out period. Blood samples were collected at predetermined time intervals until 72 hours post dose and irbesartan concentration was quantified with a validated HPLC method. Individual plasma irbesartan concentration-time profile was analyzed for pharmacokinetic parameters.Maximum plasma concentrations (Cmax) of 3,617.19 and 3,295.77 ng/mL for test and reference, respectively, were achieved. Areas under the plasma concentration-time curve; AUC0-t and AUC0-∞ were 15,304.65 and 15,638.90 ng×h/mL for test and 15,389.21 and 15,730.34 ng×h/mL for reference. The median tmax was 1.50 hours and 1.25 hours for test and reference, respectively. Plasma elimination half-lives (t1/2) were 7.35 hours and 8.09 hours for test and reference, respectively. Primary pharmacokinetic parameters Cmax, AUC0-t, and AUC0-∞ were tested parametrically by analysis of variance (ANOVA), and it revealed no statistically significant difference (defined as p < 0.05) between the corresponding Cmax, AUC0-t, and AUC0-∞ with respect to sequence, volunteers, period and formulation. The 90% confidence intervals for the ratio of test and reference product of the parameters Cmax, AUC0-t, and AUC0-∞ were within 80 - 125% (100.13 - 121.40% for Cmax, 90.83 - 106.86% for AUC0-t and 91.11 - 106.55% for AUC0-∞).The two products were bioequivalent in terms of both rate and extent of drug absorption into systemic circulation.