Twenty-four hour blood pressure effect of once-daily lisinopril, enalapril, and placebo in patients with mild to moderate hypertension.

This multicentre, double-blind, parallel-group, placebo-controlled study compared the antihypertensive effects of equal doses of two long-acting angiotensin converting enzyme (ACE) inhibitors. After a two-week, placebo run-in phase, 110 patients with mild to moderate hypertension were randomised to receive 10 mg lisinopril or enalapril, or placebo for 4 weeks. Office BPs were measured at regular intervals throughout the study. Twenty-four hour ambulatory blood pressure (ABP) was measured at baseline and after the first and final doses of study drug. Serum ACE activity and aldosterone were obtained concomitantly with each ABP monitoring. Office BP differences from placebo reached (P less than 0.05) or approached (P less than 0.10) statistical significance at all observations for the lisinopril group but were not significant for any observation in the enalapril group and approached significance on two occasions. After four weeks of treatment, ABP analysis revealed that the lisinopril and enalapril groups, when compared with placebo, had similar and significant systolic and diastolic AUC reductions (P less than 0.01) from baseline over the 24 h dosing interval. During the second half of the dosing interval, 13-24 h post drug administration, the lisinopril group was significantly different from placebo (systolic BP, P = 0.002; diastolic BP, P = 0.005) while the enalapril group was not. Both drugs were well tolerated. The results indicate that monotherapy with 10 mg of lisinopril is as effective as with 10 mg of enalapril, and that ABP monitoring is useful in more precisely depicting the clinical effect of the known pharmacokinetic properties of these two agents.