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# ACE Inhibitors ## Overview Angiotensin-Converting Enzyme (ACE) 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, thereby leading to vasodilation and reduced blood pressure. ## Primary Indications * Hypertension * Congestive Heart Failure (CHF) * Post-myocardial infarction (MI) with evidence of left ventricular dysfunction * Diabetic nephropathy * Chronic kidney disease (CKD) with proteinuria ## Adult Dosing Dosing is highly individualized and depends on the specific agent and indication. Common starting doses are often low and titrated upwards. * **Hypertension:** Typical starting doses vary by agent (e.g., lisinopril 10 mg PO daily, enalapril 5 mg PO daily, ramipril 2.5 mg PO daily). Maximum doses also vary (e.g., lisinopril 40 mg PO daily, enalapril 40 mg PO daily, ramipril 10 mg PO daily). * **Heart Failure:** Similar starting doses as hypertension, with titration based on clinical response and tolerability. Maximum doses are often similar to hypertension, but may be higher for some agents in specific guidelines. * **Post-MI:** Generally initiated within 24 hours of MI if no contraindications exist. Dosing is typically similar to hypertension/heart failure. ## Pediatric Dosing ACE inhibitors are used in pediatric patients for hypertension and sometimes heart failure. Dosing is weight-based and varies significantly by age and indication. Specific protocols or guidelines should be consulted. * **Hypertension:** Doses vary widely. For example, enalapril may be dosed from 0.07 to 0.2 mg/kg/day. * **Heart Failure:** Dosing is also weight-based and individualized. ## Dose Adjustments * **Renal Impairment:** Dose reduction is often required in patients with moderate to severe renal impairment. Specific reductions depend on the agent and creatinine clearance. * **Hepatic Impairment:** Use with caution; dose adjustments may be needed. ## 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 (risk of fetal injury or death) * Known hypersensitivity to ACE inhibitors ## Adverse Effects * **Common:** Cough (dry, persistent), dizziness, headache, fatigue, hyperkalemia, hypotension. * **Serious:** Angioedema (can be life-threatening, particularly affecting the airway), acute kidney injury (especially in patients with bilateral renal artery stenosis), severe hypotension. ## Key Drug Interactions * **Potassium-Sparing Diuretics (e.g., spironolactone, amiloride), Potassium Supplements, Trimethoprim:** Increased risk of hyperkalemia. * **NSAIDs, COX-2 Inhibitors:** May reduce antihypertensive effect and increase risk of renal impairment, especially in volume-depleted patients. * **Diuretics (especially loop and thiazide diuretics):** Increased risk of symptomatic hypotension, particularly upon initiation. * **Aliskiren:** Increased risk of hyperkalemia, hypotension, and renal dysfunction. Contraindicated in diabetic patients. * **mTOR Inhibitors (e.g., sirolimus, everolimus):** Increased risk of angioedema. * **Lithium:** ACE inhibitors can reduce lithium clearance, increasing the risk of lithium toxicity. ## Monitoring * **Baseline:** Serum creatinine, electrolytes (especially potassium), blood pressure. * **During Therapy:** * Blood pressure (regularly) * Serum creatinine and potassium (1-2 weeks after initiation or dose increase, then periodically as clinically indicated) * Signs/symptoms of angioedema or hypersensitivity. ## Clinical Pearls * The characteristic dry cough is due to bradykinin accumulation and typically resolves upon discontinuation. * Angioedema can occur at any time during therapy and is a medical emergency. * Initiate at a low dose and titrate slowly, especially in elderly patients, those with heart failure, or renal impairment. * Monitor renal function and potassium closely, particularly in patients with underlying renal disease, dehydration, or concomitant use of other nephrotoxic agents or potassium-retaining drugs. * Discontinue immediately if angioedema occurs. *** *Disclaimer: This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider and refer to the most current prescribing information for definitive guidance.*