ACE Inhibitor

ACE Inhibitor, any of a group of drugs used to treat high blood pressure (hypertension). ACE inhibitors are also used to treat congestive heart failure, heart attacks, and kidney disease in diabetic patients. Properly known as angiotensin-converting enzyme (ACE) inhibitors, these drugs work by interfering with the enzymes that convert an inactive chemical known as angiotensin I to an active form, angiotensin II. Angiotensin II increases the retention of salt and water in the body, raising blood pressure. Inhibiting the formation of angiotensin II results in relaxed arterial walls and lowered blood pressure.

ACE inhibitors are prescription drugs available in tablets and capsules that are taken orally. Dosages range from 2.5 to 450 mg per day, depending on the particular type of ACE inhibitor and the condition being treated. An injectable liquid form is typically prescribed in 1.25-mg doses administered every six hours. Effectiveness may not be apparent for two to four weeks. Because ACE inhibitors control but do not cure high blood pressure, they are often used in long-term therapy (months to years) even after symptoms are relieved. Specific ACE inhibitors include captopril, enalapril, and lisinopril.

ACE inhibitors should not be taken by pregnant women as the drugs can harm the fetus, especially in the second and third trimesters. These drugs increase the level of potassium in the blood, so other medications and diet supplements that contain potassium (or that affect potassium levels) such as diuretics should be used with caution.

Potential side effects associated with ACE inhibitors include abdominal pain, constipation, diarrhea, fatigue, insomnia, headache, and vomiting. Less common side effects include anemia, chest pain, changes in heart rhythm, or heart attack.