Characteristics of a new angiotensin converting enzyme inhibitor: delapril. Delapril, a nonsulfhydryl angiotensin converting enzyme (ACE) inhibitor, which has an indanylglycine moiety differing from the proline moiety of captopril or enalapril, is an esterified prodrug that is converted in vivo to its active metabolites. Delapril effectively inhibits rabbit lung ACE activity and lowers blood pressure in spontaneously hypertensive rats. Delapril has several characteristics that differ from captopril and enalapril, including high lipophilicity and weak bradykinin potentiating action. Delapril is a more potent inhibitor of vascular wall ACE activity than enalapril or captopril. It also shows a weaker potentiating action on the citric acid-induced cough in the guinea pig model compared with captopril and enalapril. In 12 out of 150 patients with essential hypertension who complained of cough during treatment with enalapril, changing to delapril resulted in resolution of the cough in 6 out of 12 of these patients: the percentage of patients in the total population with cough decreased from 8% to 4%. 