The primary objective of this randomised, placebo- controlled, double-blind, crossover study, was to evaluate and compare the longer term effects of the
angiotensin II type 1 receptor antagonist losartan and the converting
enzyme inhibitor enalapril on 24-h ambulatory blood pressure (BP). After a 4-week placebo run-in period, nine patients with
essential hypertension entered the double-blind phase of the study, which consisted of three 6-week periods during which patients were treated with placebo,
enalapril 20 mg o.d. or
losartan 50 mg o.d.
Losartan and
enalapril, taken between 07.00 and 08.00, reduced ambulatory BP throughout the 24-h period. Average night time BP was reduced from 133/85 mm Hg on placebo to 124/78 mm Hg on
enalapril and to 126/77 mm Hg on
losartan. Daytime BP averaged 157/101 mm Hg on placebo, and was significantly lower during
enalapril (142/91 mm Hg) than during
losartan treatment (147/95 mm Hg). Clinic BP, measured 2 to 4 hours after
drug intake, was reduced to the same extent by both drugs. The
losartan-induced BP changes were significantly related to those obtained with
enalapril (0.63 < r < 0.93). Ambulatory BP monitoring was repeated after 4 weeks of combined
therapy in six patients. The BP lowering effect of the combination was not significantly better than that achieved with
enalapril alone. In conclusion,
losartan 50 mg o.d. and
enalapril 20 mg o.d. lower BP to approximately the same extent, except for a more pronounced effect of
enalapril on daytime ambulatory BP. The current study does not provide convincing evidence that addition of
losartan to
enalapril in the doses used further reduces BP.