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# ACE Inhibitors
## Overview
Angiotensin-Converting Enzyme (ACE) inhibitors are a class of medications primarily used to treat cardiovascular conditions. 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 (reduced ejection fraction)
* Myocardial Infarction (post-MI management)
* Diabetic Nephropathy (proteinuria reduction)
## Adult Dosing
Dosing varies significantly by agent. Titration is usually required.
* **Hypertension:** Initial doses are typically low and titrated up based on blood pressure response. Examples:
* Lisinopril: 10 mg once daily, titrate to 40 mg daily.
* Ramipril: 2.5 mg once daily, titrate to 10 mg daily.
* Enalapril: 5 mg once or twice daily, titrate to 10-20 mg daily.
* **Heart Failure:** Lower initial doses are used and titrated up slowly. Examples:
* Lisinopril: 5 mg once daily, titrate to 20 mg daily.
* Ramipril: 2.5 mg twice daily, titrate to 5 mg twice daily, then potentially 10 mg twice daily.
* Enalapril: 2.5 mg twice daily, titrate to 5-10 mg twice daily.
* **Post-Myocardial Infarction:** Started within 24 hours in hemodynamically stable patients. Examples:
* Captopril: 6.25 mg three times daily, titrate to 12.5 mg three times daily, then 25 mg three times daily.
* Lisinopril: 5 mg once daily, titrate to 10 mg daily.
* **Diabetic Nephropathy:** Examples:
* Lisinopril: 10 mg once daily, titrate to 20 mg daily.
* Ramipril: 5 mg once daily, titrate to 10 mg daily.
## Pediatric Dosing
Dosing is weight-based and varies by agent. Specific protocols should be consulted.
* **Hypertension:**
* Enalapril: 0.07-0.1 mg/kg/dose every 12-24 hours. Max 0.5 mg/kg/day or 40 mg/day.
* Lisinopril: 0.07-0.2 mg/kg/dose once daily. Max 20 mg/day (for ages 6-16).
## Dose Adjustments
* **Renal Impairment:** Reduce dose or increase dosing interval. For severe renal impairment (CrCl < 30 mL/min), specific agents may require significant dose reduction or avoidance.
## Contraindications
* History of angioedema related to previous ACE inhibitor treatment.
* Hereditary or idiopathic angioedema.
* Concomitant use with aliskiren in patients with diabetes mellitus.
* Pregnancy (especially second and third trimesters).
## Adverse Effects
* Cough (dry, persistent)
* Hypotension
* Dizziness
* Hyperkalemia
* Acute Kidney Injury (especially in patients with bilateral renal artery stenosis)
* Angioedema (rare but life-threatening)
* Fatigue
* Rash
## Key Drug Interactions
* **Potassium-Sparing Diuretics, Potassium Supplements, Salt Substitutes:** Increased risk of hyperkalemia.
* **NSAIDs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Aliskiren:** Increased risk of hyperkalemia, hypotension, and renal dysfunction. Avoid in diabetics.
* **ARBs:** Increased risk of hyperkalemia and renal dysfunction.
* **Lithium:** ACE inhibitors may decrease lithium clearance, increasing lithium toxicity risk.
## Monitoring
* Blood pressure
* Serum potassium
* Renal function (serum creatinine, BUN)
* Signs and symptoms of angioedema
## Clinical Pearls
* The characteristic dry cough is thought to be due to bradykinin accumulation.
* Angioedema can occur at any time and requires immediate discontinuation of the ACE inhibitor.
* Use with caution in patients with bilateral renal artery stenosis due to the risk of acute kidney injury.
* Monitor potassium closely, especially in patients with renal impairment or those taking potassium-sparing agents.
* Discontinue ACE inhibitors during pregnancy.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the current official prescribing information and relevant clinical guidelines for complete and up-to-date drug information before making any clinical decisions.
