Immediate blood pressure effects of the renin inhibitor enalkiren and the angiotensin-converting enzyme inhibitor enalaprilat

Abstract

The antihypertensive effects of the renin inhibitor enalkiren were compared with those of the angiotensin-converting enzyme inhibitor enalaprllat in 17 hypertensive patients (14 white, 3 black; mean age 57 years), whose renin systems had been stimulated by diuretic pretreatment. Patients were studied on 3 separate in-hospital days. On the first study day patients received placebo alone. On day 2 they received intravenous bolus doses of enalkiren (0.03 to 1.0 mg/kg), and on day 3, intravenous bolus doses of enalaprilat (0.625 to 1.25 mg). Each agent reduced systolic ( p < 0.01) and diastolic ( p < 0.01) blood pressures (BP) from baseline levels. The acute decrease in systolic BP of 18.5 ± 0.4 mm Hg during enalkiren tended to be greater ( p < 0.01) than the decrease of 12.6 ± 0.7 mm Hg during enalaprilat. Decreases in diastolic BP during enalkiren (11.9 ± 0.4 mm Hg) were also slightly greater ( p < 0.1) than those during enalaprilat (9.2 ± 0.4 mm Hg). Based on prestudy plasma renin activity (PRA), patients were divided into “high” renin (PRA >3.5 ng angiotensin l/ml/hr; n = 6) and “low/normal” renin (<3.5 ng angiotensin l/ml/hr; n = 11) groups. Reductions in diastolic BP in the “high” renin group during enalkiren ( 30 ± 5 20 ± 3 mm Hg ) tended to be greater ( p < 0.07) than those during enalaprilat ( 23 ± 7 14 ± 1 mm Hg ); differences were not significant in the “low/normal” group ( 12 ± 2 7 ± 2 and 7 ± 2 8 ± 1 mm Hg , respectively). Thus the renin inhibitor is at least as effective as the ACE inhibitor in its immediate BP-lowering effects in hypertensive patients.