Long-term antihypertensive, metabolic and cellular effects of enalapril

Fifty-three patients with mild to moderate essential hypertension were treated with enalapril (10-40 mg q.d.) alone, in combination with a fixed dose of hydrochlorothiazide (50 mg/day), or in a randomized cross-over study with varying dosages of hydrochlorothiazide (50, 25, 12.5 mg/day). Normalization of blood pressure was obtained in 47% of the patients after enalapril. In the remaining patients, all except four were normalized by the combination with hydrochlorothiazide. The addition of hydrochlorothiazide was required in six patients who had optimally responded to enalapril during the first three months. In the cross-over study, diastolic blood pressure was maintained below 95 mmHg with all the doses of diuretic used in association with 40 mg enalapril. No adverse metabolic (blood glucose, cholesterol, triglycerides), renal (creatinine clearance, urinary lysozyme and gamma-GT) or haematological (total and differential counts) effects were observed after long-term treatment for one year with enalapril alone or in combination with hydrochlorothiazide. Blood uric acid decreased significantly after enalapril and tended to increase after the combination with hydrochlorothiazide. Enalapril increased Na/K ATPase activity on erythrocyte membranes thus reducing intracellular sodium and increasing potassium.