OBJECTIVETo evaluate the efficacy and safety of olmesartan medoxomil compared with losartan potassium in patients with mild to moderate essential hypertension.

METHODThis is a randomized, double-blind, double-dummy, active-controlled, parallel, multi-center study. After a 2-week placebo run-in period, a total of 287 eligible subjects were randomized at 1:1 ratio to receive olmesartan medoxomil 20 mg or losartan potassium 50 mg, once daily for 8 weeks. The blood pressure was assessed after 4 weeks treatment. If the subject's seating diastolic blood pressure (SeDBP) was still >or=90 mm Hg, the dosage was doubled for another 4 weeks; for those subjects whose SeDBP was <90 mm Hg after 4-week treatment, the initial dosage remained unchanged and the treatment continued until completion of the study.

RESULTS(1) The mean trough reduction in SeDBP from baseline in olmesartan group was significantly greater than that in losartan group after 4 weeks (11.72 mm Hg vs 9.23 mm Hg, P=0.004) and 8 weeks treatment (12.94 mm Hg vs 11.01 mm Hg, P=0.035). (2) The number and percentage of responders in olmesartan group (81, 65.3%) were statistically higher than those (68, 52.7%) in losartan group (P=0.028) after 4 weeks treatment and were similar between the two groups after 8 weeks treatment (P>0.05). (3) Individual and overall trough/peak ratios of DBP and SBP in 24-hour ambulatory blood pressure monitoring were higher in olmesartan group than losartan group. The hypotensive effect of olmesartan was more durable than losartan at 24 hour interval. (4) The incidence of study drug-related adverse events (AEs) in olmesartan group (10.5%) was similar as that in losartan group (13.9%, P>0.05). Most of these AEs were mild and transient.

CONCLUSIONThis study shows that olmesartan medoxomil, at oral dose of 20 mg-40 mg once daily was effective and safe for hypertension treatment and the hypotensive effect was superior to losartan potassium (50 mg-100 mg once daily).