Imidapril is a pro-drug which is hydrolysed in vivo to form an active metabolite, imidaprilat. Imidaprilat inhibits the angiotensin-converting enzyme (ACE). This enzyme catalyses the conversion of angiotensin I to angiotensin II in the blood plasma and tissues and inhibits the breakdown of bradykinin. As angiotensin II has a potent vasoconstrictive action, while bradykinin is a vasodilator, the reduced formation of angiotensin II and the inhibition of bradykinin breakdown lead to vasodilation. Imidapril reduces heart preload and afterload, and decreases blood pressure without any compensatory increase in the heart rate in dogs. It is indicated in the treatment of moderate to severe heart failure by mitral regurgitation or by dilated cardiomyopathy