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## Angiotensin-Converting Enzyme (ACE) Inhibitors
### Overview
ACE inhibitors are a class of medications that block the action of the angiotensin-converting enzyme, leading to vasodilation and reduced sodium and water retention. This results in a decrease in blood pressure.
### Primary Indications
* Hypertension
* Heart failure (systolic dysfunction)
* Post-myocardial infarction (to improve survival)
* Diabetic nephropathy (proteinuric kidney disease)
### Adult Dosing
Dosing varies significantly by specific agent. Titration is common, starting with a low dose and increasing gradually to achieve the therapeutic goal while monitoring for adverse effects.
* **Hypertension:** Typical starting doses include:
* Lisinopril: 10 mg PO once daily
* Enalapril: 5 mg PO once or twice daily
* Ramipril: 2.5 mg PO once daily
* Benazepril: 10 mg PO once daily
* Maximum doses vary by agent and indication, often ranging from 40 mg daily for lisinopril and enalapril to 20 mg daily for ramipril and benazepril in hypertension.
* **Heart Failure:**
* Enalapril: Starting dose 2.5 mg to 5 mg PO twice daily, titrating up to target doses of 10 mg to 20 mg PO twice daily.
* Lisinopril: Starting dose 5 mg PO once daily, titrating up to target doses of 10 mg to 40 mg PO once daily.
* Ramipril: Starting dose 1.25 mg to 2.5 mg PO once daily, titrating up to target doses of 5 mg to 10 mg PO once daily.
* **Post-Myocardial Infarction:** Similar to heart failure dosing, initiated within 24 hours of MI if hemodynamically stable.
* **Diabetic Nephropathy:** Doses often similar to those used for hypertension, aiming for maximal tolerated dose to reduce proteinuria.
### Pediatric Dosing
Dosing in children is typically weight-based and varies by specific agent.
* **Hypertension:**
* Enalapril: 0.07 mg/kg/day PO divided BID. Maximum: 0.61 mg/kg/day or 40 mg/day.
* Lisinopril: 0.07 mg/kg/day PO once daily. Maximum: 0.61 mg/kg/day or 40 mg/day.
* Note: Dosing is highly variable and may depend on local protocols or specialist recommendations.
### Dose Adjustments
* **Renal Impairment:** Initial doses should be reduced in patients with renal insufficiency (serum creatinine > 1.3 mg/dL or GFR < 30 mL/min/1.73 m²). Further adjustments based on renal function and potassium levels are often necessary.
* **Hepatic Impairment:** Dose reduction may be considered for some agents, particularly enalapril, due to decreased metabolism.
### Contraindications
* History of angioedema related to previous ACE inhibitor treatment
* Concomitant use with aliskiren in patients with diabetes mellitus or moderate to severe renal impairment
* Pregnancy (especially second and third trimesters)
* Known hypersensitivity to the specific ACE inhibitor
### Adverse Effects
* **Common:** Cough (dry, persistent), dizziness, hypotension, headache, fatigue, hyperkalemia.
* **Less Common/Serious:** Angioedema (including laryngeal edema), acute kidney injury, rash, taste disturbances, neutropenia, hepatotoxicity.
### Key Drug Interactions
* **Potassium-sparing diuretics, potassium supplements, aliskiren, and ARBs:** Increased risk of hyperkalemia.
* **NSAIDs:** May reduce antihypertensive effect and increase risk of renal impairment, especially in volume-depleted patients.
* **Lithium:** ACE inhibitors can increase serum lithium levels, potentially leading to toxicity.
* **Diuretics:** Increased risk of symptomatic hypotension, especially with concurrent diuretic use and volume depletion.
### Monitoring
* **Blood Pressure:** Regularly monitor to assess efficacy and guide titration.
* **Serum Creatinine and Potassium:** Baseline and periodically thereafter, especially after dose increases or in patients with renal impairment or risk factors for hyperkalemia.
* **Renal Function:** Monitor for signs of worsening renal function.
* **Angioedema:** Educate patients to report any signs immediately.
### Clinical Pearls
* The characteristic dry cough is often a reason for discontinuation, but may resolve with continued therapy or by switching to an ARB.
* Start low and titrate slowly, particularly in elderly patients, those with heart failure, or renal impairment.
* Hypotension is more likely upon initiation or dose increase, especially in volume-depleted patients or those on diuretics.
* ACE inhibitors are generally considered renoprotective in patients with diabetes and proteinuria.
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*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 best course of treatment for your specific condition. Verify current prescribing information for any medication before use.*
