Randomized, double-blind comparison of irbesartan and enalapril for treatment of mild to moderate hypertension.

BACKGROUND: Irbesartan is a newly developed angiotensin II receptor antagonist. Its antihypertensive efficacy and safety in Taiwanese patients with mild to moderate hypertension remains to be determined.

METHODS: This was a multicenter, double-blind, randomized, parallel group study. One hundred and sixteen patients from three centers were enrolled. After a placebo lead-in period of 14 days, 55 patients (24-75 years-of-age) who had a mean seated diastolic blood pressure of 95 to 110 mmHg were randomized to once-daily treatment with irbesartan 150 mg or enalapril 10 mg. Doses were doubled at week 4 if trough seated diastolic blood pressure was 90 mmHg or more. Trough blood pressure was measured at zero, two, four and eight weeks of treatment.

RESULTS: Both treatments lowered blood pressure with no significant difference in efficacy between treatment groups. Irbesartan 150 mg to 300 mg provided reductions in trough seated systolic and diastolic blood pressures at week 8 of -16.5 mmHg and -7.2 mmHg, respectively, with 36% of patients having a favorable response. Similarly, enalapril 10 mg to 20 mg reduced systolic and diastolic blood pressure by -10.6 mmHg and -5.0 mmHg, respectively, with a response rate of 43%. Headache, malaise and dizziness were the major adverse reactions observed in both groups. The incidence of drug-related cough was significantly higher with enalapril (18%) than with irbesartan (0%).

CONCLUSIONS: Irbesartan 150 mg to 300 mg once daily was as effective in lowering blood pressure as enalapril 10 mg to 20 mg once daily. Both irbesartan and enalapril were well tolerated, while there was a significantly lower incidence of cough with irbesartan compared with enalapril.