Enalapril in essential hypertension: the comparative effects of additional placebo, nicardipine and chlorthalidone.

The effect of adding placebo, a calcium antagonist, nicardipine and a thiazide diuretic, chlorthalidone, each for 2 weeks, to ongoing treatment with the ACE inhibitor, enalapril was evaluated in seven patients with essential hypertension. Compared with placebo, nicardipine and chlorthalidone both significantly enhanced the antihypertensive effect of enalapril: average blood pressure reductions over 8 h were respectively 26/16 and 33/17 mm Hg (supine) but the time-course of these augmented effects was significantly different. In particular, blood pressure control with the addition of nicardipine, despite apparently being at steady state, was significantly attenuated during the latter part of the dosage interval and therefore was less well sustained at 24 h. In contrast, an effect throughout 24 h appeared possible with the chlorthalidone-enalapril combination.