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# ACE Inhibitors ## Overview ACE (Angiotensin-Converting Enzyme) inhibitors are a class of medications primarily used to treat hypertension and heart failure. They work by blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, leading to vasodilation and reduced blood pressure. ## Primary Indications * Hypertension * Heart failure (NYHA class II-IV) * Left ventricular dysfunction post-myocardial infarction * Diabetic nephropathy (in patients with hypertension and/or diabetes) ## Adult Dosing Dosing varies significantly by specific agent and indication. Titration is typically initiated at a low dose and gradually increased to achieve therapeutic goals while monitoring for adverse effects. * **Hypertension:** Initial doses depend on the agent (e.g., enalapril 2.5-5 mg PO BID, lisinopril 5-10 mg PO daily, ramipril 1.25-2.5 mg PO daily). Maximum doses also vary (e.g., enalapril 40 mg PO daily, lisinopril 40 mg PO daily, ramipril 10 mg PO daily). * **Heart Failure:** Initial doses are lower than for hypertension (e.g., enalapril 2.5 mg PO BID, lisinopril 2.5-5 mg PO daily, ramipril 1.25-2.5 mg PO BID). Doses are titrated upwards (e.g., enalapril up to 10-20 mg PO BID, lisinopril up to 20 mg PO daily, ramipril up to 5 mg PO BID). ## Pediatric Dosing * **Hypertension:** Generally initiated at lower doses and titrated. For example, enalapril: 0.07 mg/kg/dose PO once or twice daily, titrating to a maximum of 0.5 mg/kg/day (or 40 mg/day total). Benazepril: 0.1 mg/kg/day PO once daily, titrating to a maximum of 0.6 mg/kg/day (or 20 mg/day total). Pediatric dosing can be highly variable and should be guided by specific product labeling and clinical expertise. ## Dose Adjustments * **Renal Impairment:** Dose reduction is typically required. Specific recommendations vary by agent and severity of renal impairment (e.g., initial doses may be halved in moderate to severe renal insufficiency). * **Hepatic Impairment:** Use with caution, especially in severe hepatic impairment. Dose adjustments may be necessary, though specific guidelines are often lacking. ## Contraindications * History of angioedema related to previous ACE inhibitor treatment. * Hereditary or idiopathic angioedema. * Concomitant use with aliskiren in patients with diabetes or renal impairment. * Pregnancy (especially second and third trimesters). ## Adverse Effects * **Common:** Cough (dry, persistent), dizziness, hypotension, hyperkalemia, fatigue, headache. * **Serious:** Angioedema (can be life-threatening), acute kidney injury, severe hypotension, hyperkalemia. ## Key Drug Interactions * **Potassium-Sparing Diuretics & Potassium Supplements:** Increased risk of hyperkalemia. * **NSAIDs & COX-2 Inhibitors:** May reduce antihypertensive effect and increase risk of renal impairment. * **Aliskiren:** Increased risk of adverse events, including hyperkalemia and hypotension, especially in patients with diabetes or renal impairment. * **Lithium:** ACE inhibitors can decrease lithium clearance, increasing lithium toxicity risk. * **Diuretics:** Additive hypotensive effect. ## Monitoring * **Blood Pressure:** Regularly monitor BP to assess efficacy and guide titration. * **Renal Function:** Baseline and periodic monitoring of serum creatinine and BUN. * **Potassium:** Baseline and periodic monitoring of serum potassium. * **Angioedema Symptoms:** Counsel patients to report any signs of angioedema immediately. ## Clinical Pearls * The characteristic dry cough is thought to be due to increased bradykinin levels and typically resolves upon discontinuation. * Angioedema is a medical emergency and requires immediate discontinuation of the ACE inhibitor. * Initiate at low doses, especially in patients who are volume-depleted, elderly, or have renal impairment, to minimize the risk of hypotension. * Closely monitor for hyperkalemia, particularly in patients with renal impairment or those taking potassium-sparing diuretics or supplements. * Switching to an angiotensin II receptor blocker (ARB) is often considered for patients who develop a cough or angioedema while on an ACE inhibitor, though cross-reactivity exists. *** *This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the appropriateness of any medication for your specific condition. Verify current prescribing information and local protocols.*