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## Overview Angiotensin-Converting Enzyme (ACE) inhibitors are a class of medications used primarily 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 * Heart Failure (systolic dysfunction) * Post-myocardial infarction (to reduce mortality and prevent ventricular remodeling) * Diabetic nephropathy (in patients with proteinuria) ## Adult Dosing Dosing is highly individualized and depends on the specific ACE inhibitor and indication. Titration is usually required. * **Hypertension:** Typical starting doses vary by agent (e.g., enalapril 5 mg BID, lisinopril 10 mg daily, ramipril 2.5 mg daily). Maximum doses also vary (e.g., enalapril 40 mg daily, lisinopril 40 mg daily, ramipril 10 mg daily). * **Heart Failure:** Similar starting doses to hypertension, but often titrated to higher doses (e.g., enalapril 10 mg BID, lisinopril 10 mg daily, ramipril 10 mg daily) based on patient tolerance and clinical response. * **Post-MI:** Typically started within 24 hours of MI (e.g., captopril 6.25 mg TID, ramipril 2.5 mg BID). Dosing is then adjusted based on tolerance and hemodynamic status. * **Diabetic Nephropathy:** Similar to hypertension dosing, often titrated to target blood pressure and proteinuria reduction. ## Pediatric Dosing ACE inhibitor use in pediatrics is less established, and dosing often requires specialized consultation. * **Hypertension:** Dosing is highly variable by age and indication. For example, enalapril has been used in children, with initial doses of 0.07-0.1 mg/kg/day, titrated to a maximum of 0.5 mg/kg/day (or 20 mg/day, whichever is less). Other agents may have different pediatric recommendations. ## Dose Adjustments * **Renal Impairment:** Reduce initial dose and titrate slowly. Monitor serum creatinine and potassium. For moderate to severe renal impairment (CrCl < 30 mL/min), specific dose adjustments are recommended for each agent (e.g., lisinopril 5 mg daily). * **Hepatic Impairment:** Generally, no dose adjustment is needed, but caution is advised. ## Contraindications * History of angioedema related to previous ACE inhibitor treatment * Concomitant use with aliskiren in patients with diabetes mellitus or renal impairment * Pregnancy (especially in the second and third trimesters) * Known hypersensitivity to ACE inhibitors ## Adverse Effects * **Most Common:** Dry cough, dizziness, hypotension, hyperkalemia, fatigue, headache. * **Serious:** Angioedema (can be life-threatening, particularly affecting the airway), acute kidney injury (especially in patients with bilateral renal artery stenosis or severe heart failure), rash, elevated liver enzymes. ## Key Drug Interactions * **Potassium-sparing diuretics and potassium supplements:** Increased risk of hyperkalemia. * **NSAIDs:** May reduce antihypertensive effect and increase risk of renal impairment. * **Diuretics:** Additive hypotensive effect. Risk of severe hypotension, especially after the first dose of ACE inhibitor. * **Aliskiren:** Increased risk of hyperkalemia, hypotension, and renal impairment. Avoid in patients with diabetes or renal impairment. * **ARBs (Angiotensin II Receptor Blockers):** Increased risk of hyperkalemia, hypotension, and renal impairment. Avoid concomitant use. * **Lithium:** ACE inhibitors can decrease lithium clearance, increasing lithium toxicity risk. Monitor lithium levels closely. * **mTOR inhibitors (e.g., sirolimus, everolimus):** Increased risk of angioedema. ## Monitoring * **Blood Pressure:** Regularly, especially after dose initiation or changes. * **Renal Function:** Serum creatinine and blood urea nitrogen (BUN) at baseline and periodically. * **Serum Potassium:** At baseline and periodically, especially in patients with renal impairment, heart failure, or those taking potassium-sparing diuretics. * **Angioedema:** Educate patients to report any swelling immediately. ## Clinical Pearls * Initiate at low doses and titrate slowly to minimize side effects, particularly hypotension and cough. * The dry cough is dose-dependent and often resolves upon discontinuation. If persistent and bothersome, consider switching to an ARB. * Angioedema is a medical emergency. Discontinue ACE inhibitor immediately if suspected and manage airway if necessary. * Avoid in patients with bilateral renal artery stenosis due to risk of precipitating renal failure. * Hyperkalemia is a significant risk, especially in patients with renal insufficiency or those on other medications that increase potassium. *** *This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for definitive guidance. Dosing can vary significantly based on individual patient factors and clinical context.*