ARTICLE: PDF OnlyGadsbøll Niels; Leth, Arne; Rasmussen, Sten; Giese, Jørn; Nielsen, Meta DamkjærJournal of Cardiovascular Pharmacology: 1987 - p 163-166 Free Abstract Summary The purpose of the study was to evaluate the antihypertensive effect of enalapril administered once daily (q.d.), and to assess the effectiveness of enalapril in achieving sustained blockade of the renin–angiotensin system. The study population comprised 15 patients with uncomplicated, moderate essential hypertension whose blood pressure (BP) was not adequately controlled on hydrochlorothiazide (HCTZ) monotherapy. Enalapril 10–40 mg q.d. produced a significant fall in supine and erect BP (24 h after enalapril) that persisted during 1 year of combination therapy with HCTZ and enalapril. Blood pressure 6 h after enalapril was significantly lower than BP measured 24 h after enalapril, and occasionally at hypotensive levels. Plasma angiotensin II concentration fell significantly after enalapril with reciprocal increases in the plasma concentrations of renin and angiotensin 1. The blockade of the renin–angiotensin system was maintained throughout the study. Bradykinin could not he detected in venous blood at any time during the study. We conclude that combination therapy with HCTZ and enalapril once daily is a rational, simple, and effective treatment in patients with moderate essential hypertension. Copyright © 1987 Wolters Kluwer Health, Inc. All rights reserved.