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# ACE Inhibitors
## Overview
ACE inhibitors (e.g., lisinopril, enalapril, ramipril) are a class of medications that block the action of angiotensin-converting enzyme, leading to vasodilation and reduced sodium and water retention.
## Primary Indications
* Hypertension
* Heart failure (systolic dysfunction)
* Post-myocardial infarction (left ventricular dysfunction)
* Diabetic nephropathy (proteinuria)
## Adult Dosing
Dosing varies significantly by agent and indication. Titration is typically required.
* **Hypertension:** Initial doses vary (e.g., lisinopril 5-10 mg PO once daily, enalapril 2.5-5 mg PO once or twice daily, ramipril 2.5 mg PO once daily). Maximum daily doses also vary by agent (e.g., lisinopril 40 mg PO once daily, enalapril 40 mg PO once or twice daily, ramipril 10 mg PO once daily).
* **Heart Failure:** Initial doses are lower (e.g., lisinopril 2.5-5 mg PO once daily, enalapril 2.5 mg PO twice daily, ramipril 1.25-2.5 mg PO twice daily). Target doses aim for higher efficacy (e.g., lisinopril 20-40 mg PO once daily, enalapril 10 mg PO twice daily, ramipril 5 mg PO twice daily).
* **Post-MI:** Initiation typically 24 hours after MI (e.g., captopril 6.25 mg PO TID, then titrate; ramipril 1.25 mg PO once daily, then titrate).
* **Diabetic Nephropathy:** Initial doses as for hypertension, titrated to control proteinuria (e.g., lisinopril 10-20 mg PO once daily).
## Pediatric Dosing
Dosing is weight-based and depends on the specific agent. Always consult a reliable pediatric dosing resource.
* **Hypertension:** (e.g., Enalapril: 0.07-0.1 mg/kg/dose PO once daily, max 5 mg/day initially, may increase to 0.2 mg/kg/dose to a max of 40 mg/day; Lisinopril: 0.07-0.2 mg/kg/dose PO once daily, max 20 mg/day).
## Dose Adjustments
* **Renal Impairment:** Dose reduction is often necessary. Specific guidance depends on the agent and creatinine clearance. For example, with enalapril, if CrCl < 30 mL/min/1.73m², consider starting at 5 mg PO once daily.
* **Hepatic Impairment:** Generally no dose adjustment, but caution advised.
## Contraindications
* History of angioedema related to ACE inhibitor therapy.
* Concomitant use with aliskiren in patients with diabetes or moderate to severe renal impairment.
* Pregnancy (especially in the second and third trimesters).
## Adverse Effects
* Dry cough (most common)
* Hypotension
* Hyperkalemia
* Dizziness
* Renal dysfunction (especially in susceptible individuals)
* Angioedema (rare but life-threatening)
* Teratogenicity
## Key Drug Interactions
* **Potassium-sparing diuretics, potassium supplements, spironolactone, eplerenone, aliskiren, ARBs:** Increased risk of hyperkalemia.
* **NSAIDs:** May attenuate antihypertensive effect and increase risk of renal dysfunction.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Diuretics:** Increased risk of symptomatic hypotension, especially after the first dose.
## Monitoring
* Blood pressure
* Serum electrolytes (especially potassium)
* Renal function (serum creatinine, BUN)
* Signs/symptoms of angioedema
## Clinical Pearls
* Start at a low dose and titrate slowly, especially in patients with heart failure, volume depletion, or renal impairment.
* Monitor for hyperkalemia, particularly in patients with renal insufficiency or on potassium-sparing agents.
* Discontinue immediately if angioedema occurs.
* Advise patients about the risk of cough and to report it promptly.
* Not recommended in pregnancy.
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***Disclaimer:** This information is intended for clinical professionals. Always consult the most current prescribing information and institutional protocols for definitive guidance.*
