Comparison of effects of quinapril versus enalapril on vasoactive substances following acute myocardial infarction

The true existence of a class effect in angiotensin-converting enzyme (ACE) inhibitors remains controversial. Some research suggests that pharmacologic effects may be different among ACE inhibitors and that these differences are dictated by the propensity to penetrate vascular tissue and inhibit ACEs. This randomized, open-label trial in patients with acute myocardial infarction (AMI) explored the effects of 2 ACE inhibitors with observed differences in ability to penetrate vascular tissue. Endothelin-1 (ET-1) and total nitric oxide (NO) were measured at baseline and periodically over 14 days. ET-1 concentrations were no different between treatments; however, NO concentrations over the entire time course were significantly greater with quinapril than with enalapril (p = 0.0025). This investigation suggests a potentially greater increase in NO production with a more highly tissue-penetrating ACE inhibitor after AMI.