Comparison of Ramipril and Enalapril in Patients With Essential Hypertension

STUDY OBJECTIVE: To compare the clinical safety and efficacy of ramipril, a new long-acting nonsulfhydryl inhibitor of angiotensin-converting enzyme (ACE), with enalapril. DESIGN: A randomized, double-blind trial. SETTING: Multicenter trial involving 4 large teaching hospitals and 12 community medical centers. PATIENTS: One hundred fifty-nine patients with mild to moderate essential hypertension were enrolled. Two patients were excluded from the efficacy analysis because they failed to return for follow-up. INTERVENTIONS: Patients were randomized to receive ramipril 2.5, 5, or 10 mg, or enalapril 5, 10, or 20 mg once/day for 3 or 4 weeks. MEASUREMENTS AND MAIN RESULTS: At baseline, supine diastolic blood pressures ranged from 98-116 mm Hg. Supine and standing systolic blood pressures were reduced by 11.8 and 10.2 mm Hg with ramipril 10 mg (p < or = 0.001) and 9.3 and 10.7 mm Hg with enalapril 20 mg (p < or = 0.001). At the end of the 4-week trial, patients in all six dosage groups had clinically and statistically significant reductions in supine diastolic blood pressure compared with baseline values. The agents did not differ significantly with respect to their blood pressure-lowering effects. Both lowered plasma ACE activity; after 4 weeks, changes from baseline were highly significant for all dosage groups (p < or = 0.001). CONCLUSION: Ramipril was as effective in reducing blood pressure and was as well tolerated as enalapril. A larger average decrease in plasma ACE activity was achieved with ramipril over all dosages (71%) compared with that for enalapril (48%), suggesting that ramipril has greater ACE inhibition in the circulation.