Lisinopril and enalapril in hypertension: a comparative study using ambulatory monitoring

Detecting differences in the effect of two antihypertensive agents is bedevilled by the inherent variability of blood pressure itself. Using an ambulatory blood pressure monitoring technique, we compared, in a cross-over design study, the effects of four weeks' treatment with enalapril, 10 mg once daily, to lisinopril, 10 mg once daily, on the blood pressure of 19 patients with mild to moderate hypertension. A significant reduction in blood pressure was shown by both drugs. However, lisinopril produced a greater fall in mean 24 hour systolic pressure than did enalapril (difference; 5.94 (C.I. -0.77 to -11.1) mmHg, P = 0.027). The difference of 3.3 mmHg (C.I. +0.54 to -7.10) in diastolic pressure between the two agents, though in the same direction, was not significant. Plasma renin activity did not predict the responses to either agent. Studying the prevailing information for these two drugs one might expect there to be little difference between them when administered once daily in terms of antihypertensive effect. The explanation for the superiority of lisinopril may lie in the slightly longer pharmacokinetic half-life and possibly in differences in tissue distribution or persistence. The side effects of both drugs were mild and of similar frequency to those recorded during placebo treatment, illustrating the generally well tolerated nature of this class of antihypertensive therapy. The use of ambulatory blood pressure monitoring provides a method that can detect small, but possibly important differences between drugs. In the clinical setting it allows a more thorough assessment of a particular patient's response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)