enalapril

Enalapril is an angiotensin-converting enzyme (ACE) inhibitor used to treat hypertension and symptomatic heart failure, and to reduce mortality after myocardial infarction with left ventricular dysfunction. It is administered as the prodrug enalapril, which is rapidly converted in the liver to the active metabolite enalaprilat. By lowering angiotensin II formation, it helps relax blood vessels and decrease workload on the heart.

Enalapril inhibits ACE, reducing angiotensin II and aldosterone. This produces vasodilation, lowers blood pressure, and decreases sodium and water retention. Orally active enalapril is a prodrug; it is converted in the liver to enalaprilat, the active form. Peak enalapril is reached within 1–2 hours; enalaprilat persists longer. The drug is mainly excreted by the kidneys, requiring dose adjustment in renal impairment. An intravenous form, enalaprilat, bypasses first-pass metabolism and is used in hospital settings for hypertensive emergencies or acute heart failure; enalaprilat is not orally bioavailable.

Administration and dosage forms: Enalapril is available as oral tablets (commonly 2.5, 5, 10, and 20 mg) and as the intravenous solution enalaprilat for hospital use. Dosing is individualized with gradual titration to minimize hypotension; maximum daily doses vary by indication and guidelines.

Safety and contraindications: Common adverse effects include dizziness, cough, hypotension, and hyperkalemia. Angioedema is rare but potentially life-threatening. ACE inhibitors are contraindicated in pregnancy and in patients with bilateral renal artery stenosis or a history of ACE inhibitor–induced angioedema. Caution is advised in renal impairment and when combined with potassium-sparing diuretics or NSAIDs, which can increase the risk of kidney injury and hyperkalemia.