ACE inhibitors inhibit the actions of angiotensin converting enzyme (ACE), thereby lowering the production of angiotensin II and decreasing the breakdown of bradykinin. The decrease in angiotensin II results in relaxation of arteriole smooth muscle leading to a decrease in total peripheral resistance, reducing blood pressure as the blood is pumped through widened vessels. Its effect on bradykinin is responsible for the dry cough side effect.
Ramipril, a prodrug or precursor drug, is converted to the active metabolite ramiprilat by carboxylesterase 1. Ramiprilat is mostly excreted by the kidneys. Its half-life is variable (3–16 hours), and is prolonged by heart and liver failure, as well as kidney failure. Peak effect occurs between 3 and 6 hours after dosing, with approximately 50% of this effect retained after 24 hours.