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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) to improve survival
* Diabetic nephropathy (proteinuria reduction)
## Adult Dosing
Dosing is highly individualized and depends on the specific ACE inhibitor, indication, and patient response. Typical starting doses are low and titrated upwards.
* **Hypertension:**
* Lisinopril: Start 10 mg once daily, titrate up to 20-40 mg once daily. Max: 80 mg once daily.
* Enalapril: Start 5 mg once or twice daily, titrate up to 10-20 mg once or twice daily. Max: 40 mg twice daily.
* Ramipril: Start 2.5 mg once daily, titrate up to 5-10 mg once daily. Max: 10 mg once daily.
* **Congestive Heart Failure (CHF):**
* Lisinopril: Start 5 mg once daily, titrate up to 10-40 mg once daily.
* Enalapril: Start 2.5 mg twice daily, titrate up to 10-20 mg twice daily. Max: 40 mg twice daily.
* Ramipril: Start 1.25-2.5 mg twice daily, titrate up to 5-10 mg twice daily.
* **Post-MI:**
* Lisinopril: Start 5 mg within 24 hours of MI, then 5 mg daily for 6 days, then 10 mg daily.
* Ramipril: Start 1.25 mg once daily, titrate up to 5 mg twice daily (if tolerated).
* **Diabetic Nephropathy:**
* Lisinopril: Start 10 mg once daily, titrate up to 20 mg once daily.
## Pediatric Dosing
* **Hypertension:**
* Enalapril: 0.07-0.1 mg/kg/dose orally once daily, titrate up to 0.21 mg/kg/dose once daily (max 20 mg/day).
* Lisinopril: 0.07 mg/kg/dose orally once daily (max 10 mg/day).
* Captopril: 0.3 mg/kg/dose orally three times daily, titrate up to 0.5 mg/kg/dose three times daily (max 150 mg/day).
## Dose Adjustments
* **Renal Impairment:** Initiate at lower doses and titrate cautiously. Dose reduction may be necessary based on creatinine clearance. Specific recommendations vary by agent.
* **Hepatic Impairment:** Some agents may require dose adjustment. Enalapril may have reduced efficacy.
## Contraindications
* History of angioedema related to previous ACE inhibitor treatment.
* Concomitant use with aliskiren in patients with diabetes.
* Pregnancy (especially in the second and third trimesters).
* Known hypersensitivity to the drug.
## Adverse Effects
* **Common:** Dry cough, dizziness, fatigue, headache, hyperkalemia.
* **Serious:** Angioedema (including laryngeal edema), acute kidney injury (especially in patients with bilateral renal artery stenosis), hypotension, hepatotoxicity, neutropenia.
## Key Drug Interactions
* **Potassium-sparing diuretics, spironolactone, eplerenone, potassium supplements, salt substitutes:** Increased risk of hyperkalemia.
* **NSAIDs (including COX-2 inhibitors):** May blunt the antihypertensive effect and increase risk of renal impairment, particularly in elderly or volume-depleted patients.
* **Aliskiren:** Increased risk of hyperkalemia, hypotension, and renal impairment. Avoid concurrent use in patients with diabetes.
* **ARBs:** Increased risk of hyperkalemia, hypotension, and renal impairment. Generally not recommended.
* **Lithium:** Reduced lithium clearance, leading to increased serum lithium levels and potential toxicity.
* **Diuretics (especially loop or thiazide):** Increased risk of hypotension, particularly with initial doses.
## Monitoring
* **Blood Pressure:** Regularly monitor BP, especially after dose initiation or titration.
* **Renal Function:** Monitor serum creatinine and BUN, particularly in patients with pre-existing renal disease or risk factors.
* **Potassium Levels:** Monitor serum potassium, especially in patients with renal impairment, hyperkalemia risk factors, or concurrent use of potassium-sparing agents.
* **Angioedema:** Educate patients on symptoms and to discontinue medication immediately if they occur.
## Clinical Pearls
* The characteristic dry cough is typically dose-related and may resolve upon discontinuation.
* Angioedema can occur at any time during therapy and is a medical emergency.
* Initiate at low doses and titrate slowly, especially in patients who are volume-depleted, have heart failure, or renal impairment.
* Discontinue ACE inhibitors immediately if angioedema occurs and never restart.
* Use with caution in patients with bilateral renal artery stenosis due to the risk of precipitating renal failure.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and your institution's protocols before making any treatment decisions.*
