Are all angiotensin-converting enzyme inhibitors interchangeable?

In the treatment of most medical conditions, there are many choices. A crit ical question for practicing clinicians is: "Are all drugs within a class i nterchangeable?" In the past decade, the market has seen a proliferation of drugs within popular drug classes. The original drugs within a class typic ally have better scientific documentation than the newer ones, which are of ten referred to as "me-too" drugs. Due to a lesser financial investment, th e latter may be available at a lower cost. Good reasons exist for grouping drugs, however, there is no accepted definition of the term "class effect." Although members of a drug class share main actions, they may have clinica lly important differences in terms of efficacy and safety. There are many s uch examples in the literature. This article reviews the class effect conce pt as it applies Co the angiotensin-converting enzyme (ACE) inhibitors. Onl y half of the 10 ACE inhibitors available in the U.S. have been shown to im prove survival and reduce morbidity in patients with heart failure or myoca rdial infarction. It is unknown whether the other five have the same safety and efficacy profiles or what their optimal doses are. Thus, we do not kno w whether all ACE inhibitors are fully interchangeable. The practice of med icine ought to he based on solid scientific evidence, not on assumptions or extrapolations. For our patients, such practice is a legitimate expectatio n. Therefore, it seems prudent to recommend that patients requiring ACE inh ibitor therapy be prescribed one that has been proven effective and safe. a Am Cell Cardiol 2001;37:1456-60) (C) 2001 by the American College of Cardi ology.