Quinapril hydrochloride is a hydrochloride resulting from the reaction of equimolar amounts of quinapril and hydrogen chloride. A prodrug for quinaprilat hydrochloride (by hydrolysis of the ethyl ester to the corresponding carboxylic acid), it is used as an angiotensin-converting enzyme inhibitor (ACE inhibitor) for the treatment of hypertension and congestive heart failure. It has a role as an EC 3.4.15.1 (peptidyl-dipeptidase A) inhibitor and an antihypertensive agent. It contains a quinapril(1+).