Humoral and hemodynamic effects of nitrendipine versus clonidine in patients with essential hypertension.

A single-blind, randomized controlled study was conducted to assess and compare the antihypertensive effectiveness and the effects on glucose tolerance and renin-angiotensin-aldosterone balance of nitrendipine (Bay e 5009), a new dihydropyridine calcium antagonist, and clonidine. Twenty-six outpatients with uncomplicated mild to moderate essential hypertension were randomly allocated to receive 20 mg of nitrendipine or 0.25 mg of clonidine (slow-release formulation) daily for five weeks. One patient in the clonidine group dropped out. Both treatments significantly reduced systolic and diastolic blood pressures with negligible modifications in heart rate. However, diastolic blood pressure was reduced significantly more (P less than 0.001) with nitrendipine. Accordingly, 12 of 13 patients given nitrendipine attained the goal of diastolic pressure less than or equal to 90 mmHg, according to criteria of the Hypertension Detection and Follow-up Program, while only three of 12 patients in the clonidine group achieved this goal. Side effects were mild and transient in both treatment groups. No definite trends in plasma renin activity or plasma aldosterone concentration, or in blood glucose or immunoreactive insulin (measured both in fasting conditions and after an oral glucose tolerance test), were evident when baseline and posttreatment values were compared. The results of this study suggest that nitrendipine is an effective and safe antihypertensive agent and is devoid of adverse effects on glucose tolerance and renin-aldosterone homeostasis.