SN instructed patient about the drug lisinopril is a drug of the angiotensin-converting enzyme inhibitor class used primarily in treatment of hypertension ACE is important because it is an enzyme responsible for producing the chemical, angiotensin II. Angiotensin II causes muscles in most arteries, including the arteries of the heart, to contract, thereby narrowing the arteries and elevating blood pressure. ACE inhibitors such as lisinopril lower blood pressure by reducing the production of angiotensin II, thereby relaxing arterial muscle and enlarging arteries. When the blood pressure is lower, the heart - including the failing heart - does not have to work as hard to pump blood. The arteries supplying the heart with blood also enlarge during treatment with ACE inhibitors. This increases the flow of blood and oxygen to the heart, further improving the ability of the heart to pump bloodSide effects include: dizziness due to a drop in blood pressure, trouble breathing, blistering, peeling, red skin rash, confusion, weakness, uneven heartbeat, trouble breathing, numbness or tingling in your hands, feet, or lips, dark urine or pale stools. Pt verbalized understanding.