Perindopril is an inhibitor of an enzyme (angiotensin converting enzyme) that converts angiotensin I to angiotensin II. This kind of invertase or kinase is a kind of peptidolytic enzyme. It can convert angiotensin I into angiotensin II, which is used to constrict blood vessels. It can also degrade bradykinin, which is used to dilate blood vessels, into inactive heptapeptide. Inhibition of angiotensin converting enzyme results in a decrease of angiotensin II in plasma, which leads to an increase in plasma renin activity (by inhibiting the negative feedback of renin release) and a decrease in aldosterone secretion. Because angiotensin-converting enzyme inactivates bradykinin, inhibition of angiotensin-converting enzyme can also increase the activity of circulating and local kallikrein kinin system (and thus prostaglandin system). This mechanism may be related to the effect of angiotensin converting enzyme inhibitors on lowering blood pressure, and may also be related to some side effects (such as cough). Perindopril acts through its active metabolite perindoprila.