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

Objective: Pharmacokinetics and bioequivalence of 300 mg irbesartan tablets were studied in 26 healthy Thai male volunteers.
Methods: 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.
Results: 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-∞).
Conclusion: The two products were bioequivalent in terms of both rate and extent of drug absorption into systemic circulation.