Overview of the angiotensin-converting-enzyme inhibitors

The pharmacology of angiotensin-converting-enzyme (ACE) inhibitors and their role in the renin-angiotensin system (Ras) are described, and pharmacokinetic properties and common adverse events are presented. ACE inhibitors play a vital role in the Ras by regulating the potent vasoconstrictor angiotensin II. All ACE inhibitors share the same basic structure; however, they can be separated on the basis of their functional (binding) group: carboxyl, sulfhydryl, or phosphinyl. These functional groups are, in part, responsible for differences in the pharmacokinetic and safety profiles of these agents. Captopril and lisinopril are the only ACE inhibitors that are not prodrugs requiring activation through hepatic biotransformation. Differences among the ACE inhibitors in lipophilicity are described; fosinopril has the greatest lipophilicity and lisinopril the least. ACE is found in numerous tissues, and there is increasing evidence of differences among ACE inhibitors in their ability to inhibit tissue ACE. Most ACE inhibitors are eliminated mainly by the kidneys and to a lesser extent through the liver. Lisinopril is the only ACE Inhibitor that does not require hepatic metabolism. In the selection of an ACE Inhibitor for once-daily use to treat hypertension, differences in trough-peak ratios are clinically relevant. Fosinopril, ramipril, and trandolapril have minimum trough-peak ratios of 50% or greater. ACE inhibitors are generally well tolerated, with hypotension, cough, and hyperkalemia being the most frequently reported adverse effects for the entire class. Drug interactions across the ACE Inhibitor class as well as agent-specific interactions are described. Factors to be considered in the selection of an ACE Inhibitor include differences in potency, affinity for ACE, pharmacokinetics, and toxicity that are related to structural properties of the drug; whether the trough-peak ratio enables use of a once-daily dose; and potential adverse effects related to a drug's functional (binding) group.