Angiotensin converting enzyme inhibitors: comparative structure, pharmacokinetics, and pharmacodynamics

Angiotensin converting enzyme (ACE) inhibitors are a novel class of antihypertensive and anticongestive heart failure agents with wide patient and physician acceptability. By blocking the formation of angiotensin II in blood and tissue, all ACE inhibitors significantly lower systemic vascular resistance, lower blood pressure, and improve cardiac function, while maintaining or enhancing perfusion of vital organs: kidneys, brain, and heart. Captopril is the first oral ACE inhibitor with an active sulfhydryl group. Enalapril and lisinopril are potent nonsulfhydryl inhibitors of ACE characterized by weak chelating properties. The side effects of skin rashes, pruritus, taste abnormalities, oral ulcers, pemphigus, and blood dyscrasias have been considered to be strongly characteristic of penicillaminelike drugs, including the sulfhydryl ACE inhibitors. The class effects of cough, angio-edema, hyperkalemia, nonoliguric functional renal insufficiency, and hypotension can occur with equal frequency with all ACE inhibitors. It is unclear whether the many yet investigational ACE inhibitors would have distinct advantages over captopril, enalapril, lisinopril, and enalaprilat. This paper reviews the comparative structure and clinical pharmacology of the three commercially available but chemically different oral ACE inhibitors.