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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, leading to vasodilation and reduced blood pressure.
## Primary Indications
* Hypertension
* Heart Failure (systolic dysfunction)
* Post-myocardial infarction (to improve survival)
* Diabetic nephropathy (proteinuria reduction)
## Adult Dosing
Dosing is highly individualized and depends on the specific ACE inhibitor. Examples include:
* **Benazepril:** Start 5-10 mg PO once daily; usual maintenance 20-40 mg/day (max 80 mg/day)
* **Captopril:** Start 12.5-25 mg PO BID; usual maintenance 25-50 mg TID (max 450 mg/day)
* **Enalapril:** Start 2.5-5 mg PO once or twice daily; usual maintenance 10-40 mg/day (max 40 mg/day)
* **Lisinopril:** Start 5-10 mg PO once daily; usual maintenance 10-40 mg/day (max 80 mg/day)
* **Ramipril:** Start 1.25-2.5 mg PO once daily; usual maintenance 2.5-5 mg/day (max 20 mg/day)
*Note: Initial doses are often lower in patients with heart failure or those on diuretics.*
## Pediatric Dosing
Established pediatric dosing varies by agent and indication. Dosing is often weight-based.
* **Enalapril:** Hypertension: 0.07-0.1 mg/kg/dose PO once daily (max 0.61 mg/kg/day or 40 mg/day). Heart Failure: 0.1 mg/kg/dose PO once daily (max 40 mg/day).
* **Lisinopril:** Hypertension: 0.07-0.2 mg/kg/day PO once daily (max 20 mg/day).
*Consult pediatric-specific resources for other ACE inhibitors and detailed regimens.*
## Dose Adjustments
* **Renal Impairment:** Dose reduction is often necessary, particularly with drugs renally cleared. Cautious titration is advised. Serum creatinine and potassium should be monitored.
* **Hepatic Impairment:** Generally no specific dose adjustment, but caution is advised.
## Contraindications
* History of angioedema related to previous ACE inhibitor treatment
* Concomitant use with aliskiren in patients with diabetes mellitus
* Concomitant use with sacubitril/valsartan (within 36 hours of last dose)
* Pregnancy (especially second and third trimesters)
## Adverse Effects
* **Dry Cough:** Most common; due to bradykinin accumulation.
* **Hyperkalemia:** Risk increased with renal impairment or potassium-sparing diuretics.
* **Hypotension:** Especially with first-dose or in volume-depleted patients.
* **Angioedema:** Rare but life-threatening; swelling of face, lips, tongue, throat, extremities.
* **Renal Dysfunction:** Can occur, especially in patients with bilateral renal artery stenosis or severe heart failure.
* **Dizziness, fatigue, headache.**
* **Rash.**
## Key Drug Interactions
* **Potassium Supplements and Potassium-Sparing Diuretics (e.g., spironolactone, amiloride):** Increased risk of hyperkalemia.
* **Diuretics:** Increased risk of hypotension, particularly with the first dose.
* **NSAIDs:** May reduce antihypertensive effect and increase risk of renal dysfunction.
* **Lithium:** ACE inhibitors can decrease lithium clearance, increasing lithium toxicity risk.
* **Aliskiren:** Increased risk of hyperkalemia, hypotension, and renal dysfunction. Avoid in diabetics.
* **Sacubitril/Valsartan:** Increased risk of angioedema. Avoid coadministration.
## Monitoring
* **Blood Pressure:** Regular monitoring is essential.
* **Serum Potassium:** Baseline and periodically, especially in patients with renal impairment or those on potassium-sparing agents.
* **Renal Function (Serum Creatinine, BUN):** Baseline and periodically.
* **Signs/Symptoms of Angioedema:** Patient education is crucial.
## Clinical Pearls
* ACE inhibitors are renoprotective in diabetic patients with proteinuria.
* First-dose hypotension can be minimized by initiating therapy at a lower dose, particularly in patients who are volume-depleted or on diuretics.
* If angioedema occurs, discontinue the ACE inhibitor immediately and manage airway.
* Cough is a common, bothersome side effect that may necessitate switching to an angiotensin II receptor blocker (ARB).
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for current prescribing information or professional medical advice. Always verify current drug information with official package inserts or reliable drug compendia.*
