Comparative study of the effects of three angiotensin converting enzyme inhibitors or the cough reflex

Abstract

To compare the effects of three different angioten­sin converting enzyme (ACE) inhibitors on the cough reflex, capsaicin and citric acid challenge tests were done in normal subjects and hypertensive pa­tients before and after administration of delapril, captopril, or enalapril. Two groups of 7 normal subjects (single dose study: 15 mg delapril v 18.75 mg captopril or 2.5 mg enalapril) and a group of 6 mildly hypertensive patients (1 week study: Cross­over administration of 30 mg/day delapril, 37.5 mg/day captopril, or 5 mg/day enalapril) were stud­ied. Another group of 6 patients with essential hy­pertension was treated with three ACE inhibitors for 4 weeks in a randomized order, with a 2 week washout period between active therapies. Aerosols of 1 //mol/L and 3 /zmol/L capsaicin and 0.68% citric acid in 0.9% NaCl were generated by an ultrasonic nebulizer, and the frequency of cough was counted during inhalation. Delapril treatment resulted in substantially fewer patients with a significant in­crease (^ 4 coughs during treatment than during the control period) in the frequency of cough than did captopril treatment. In the 1 and 4 week studies, enalapril and captopril had substantially more oc­currences of significantly increased capsaicin-in­duced cough than did delapril. These results indi­cate that delapril has the least cough stimulatory effect among these ACE inhibitors, which may be clinically beneficial. © 1991 by the American Journal of Hypertension, Inc.