Angiotensin converting enzyme inhibitors in congestive heart failure: Overview in comparison of captopril and enalapril

In this study, the use of enalapril and captopril is compared in the treatment of congestive heart failure. Although both drugs act on the renin-angiotensin system via converting enzyme inhibition, their different chemical structures may dispose them to different pharmacologic and physiologic activity. Both drugs exert a vasodilator effect, with reduction of left and right ventricular filling pressures and aortic impedance. In short-term hemodynamic studies, the onset of action and peak effect are earlier with captopril. Enalapril has a much more gradual onset and longer duration of action. Both drugs have a shallow dose-response curve and both produce comparable hormonal changes: an increase in plasma renin activity and a decrease in aldosterone levels. Captopril also increases prostaglandin production. Long-term efficacy trials have demonstrated symptomatic improvement in patients given captopril and those receiving enalapril who were also receiving digitalis and diuretics. Baseline hemodynamics may not predict long-term improvement. There are few adverse effects for the two drugs, but their incidences differ, suggesting a relationship to chemical structure. Recent studies in congestive heart failure suggest a reduction in mortality with various drug regimens.