Irbesartan in Primary Hypertension in Thai Patients: A Multicentre, Non-Comparative Study

Background: The angiotensin II receptor antagonist irbesartan is an effective and well-tolerated treatment for hypertension in Western societies. However, evidence of the therapeutic benefits of angiotensin II receptor antagonists is generally lacking in hypertensive Asian subjects. Objectives: This multicentre, non-comparative study assessed the efficacy and safety of once-daily irbesartan in the treatment of hypertension in a population of Thai patients. Methods: After a 3- to 4-week placebo run-in period, patients were treated with irbesartan for 12 weeks, initially with 150 mg/day for 4 weeks. At 4 weeks, patients are up-titrated from irbesartan 150 to 300 mg/day and, at 8 weeks from irbesartan 150 to 300 mg/day or from irbesartan 300 mg to irbesartan 300 mg plus hydrochlorothiazide (HCTZ)12.5 mg/day if their seated diastolic blood pressure (SeDBP) remained ≧90 mm Hg. Trough blood pressures and safety assessments were measured at intervals during the study. The primary end point was the comparison of the reduction in blood pressure at the end of the placebo run-in and irbesartan treatment periods. Safety assessments formed part of the secondary end points. Results: Significantly greater reductions in SeDBP (14.42 versus 0.11 mm Hg, p < 0.0001) and seated systolic blood pressure (SeSBP) (20.83 versus 3.15 mm Hg, p < 0.0001) were reported after 12 weeks of irbesartan compared with the placebo run-in period. After 12 weeks, the blood pressure of 56% of patients on irbesartan regimens was normalized and 77% responded to therapy. These results were similar to irbesartan treatment in the Western population. Reductions in blood pressure were recorded in all the irbesartan treatment groups. The safety profile was globally similar to that observed during the placebo run-in period. Conclusions: Once-daily irbesartan was an effective and well-tolerated agent for the treatment of hypertension in Thai patients, suggesting that dose recommendations for irbesartan in Thailand should follow those used in Western countries.