The effects of irbesartan added to hydrochlorothiazide for the treatment of hypertension in patients non-responsive to hydrochlorothiazide alone

Aim: To evaluate the antihypertensive efficacy and safety of adding irbesartan to hydrochloride (HCTZ) in patients not adequately controlled by HCTZ alone. Patients and Methods: In this multicenter study, after a single-blind, placebo lead-in period, hypertensive patients received single-blind HCTZ 25 mg once daily. After 4 weeks, 238 patients with seated diastolic blood pressure of 93–110 mmHg continued on HCTZ 25 mg once daily and were randomized to double-blind irbesartan 75 mg once daily or matching placebo for 12 weeks. At week 6, the dosage of irbesartan or placebo was doubled for seated diastolic blood pressure ≥90 mmHg. Results: At weeks 2, 6, and 12, irbesartan/HCTZ resulted in significantly greater ( P<0·01) reductions from baseline in trough seated diastolic and systolic blood pressure compared with placebo/HCTZ. At week 12, the mean reductions in trough seated diastolic and systolic blood pressure were 7·2 mmHg (95%, C.I., 5·1–9·3 mmHg) and 11·1 mmHg (95% C.I., 7·9–14·3 mmHg) greater, respectively, with irbesartan/HCTZ compared with placebo/HCTZ. At week 12, significantly ( P<0·01) more patients were normalized (trough seated diastolic blood pressure <90 mmHg) with irbesartan/HCTZ (67%) compared with placebo/HCTZ (29%). The frequency of adverse events, serious adverse events, and discontinuations attributed to adverse events was similar in both groups, and there were no clinically relevant changes in serum creatinine, potassium, or any other laboratory parameter. Conclusion: Irbesartan was effective and well tolerated when added to a background of HCTZ 25 mg in patients whose blood pressure was not adequately controlled by HCTZ alone.