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# ACE Inhibitors
## Overview
ACE inhibitors (Angiotensin-Converting Enzyme inhibitors) are a class of medications used primarily 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 (reduced ejection fraction)
* Post-myocardial infarction (to improve survival)
* Diabetic nephropathy (proteinuria)
* Chronic kidney disease (proteinuria)
## Adult Dosing
Dosing is highly individualized and titrate to effect. Specific starting doses vary by agent:
* **Benazepril:** Start 10 mg orally once daily. Max 80 mg/day.
* **Captopril:** Start 25 mg orally twice daily. Max 450 mg/day.
* **Enalapril:** Start 5 mg orally once daily. Max 40 mg/day (oral); 2.5 mg IV every 6 hours (IV).
* **Fosinopril:** Start 10 mg orally once daily. Max 80 mg/day.
* **Lisinopril:** Start 10 mg orally once daily. Max 40 mg/day.
* **Moexipril:** Start 7.5 mg orally once daily. Max 30 mg/day.
* **Perindopril:** Start 5 mg orally once daily. Max 10 mg/day.
* **Ramipril:** Start 2.5 mg orally once daily. Max 10 mg/day.
* **Trandolapril:** Start 1 mg orally once daily. Max 4 mg/day.
* **Quinapril:** Start 10 mg orally once or twice daily. Max 80 mg/day.
## Pediatric Dosing
Established pediatric dosing varies significantly by agent and indication. Consult specific pediatric guidelines or product labeling for precise recommendations. Generally, lower doses are used, and titration is guided by clinical response and blood pressure monitoring. For example:
* **Enalapril:** 0.07 mg/kg/day orally once daily (hypertension), max 0.61 mg/kg/day or 40 mg/day.
## Dose Adjustments
* **Renal Impairment:** Dose reduction is often necessary, especially in severe renal impairment. Specific recommendations vary by agent. Captopril and enalapril are renally eliminated and often require significant dose adjustments.
* **Hepatic Impairment:** Generally, no specific dose adjustment is needed for most ACE inhibitors, but caution is advised.
## Contraindications
* History of angioedema related to prior ACE inhibitor therapy.
* Concomitant use of aliskiren in patients with diabetes.
* Pregnancy (Category D, especially in the second and third trimesters).
* Known hypersensitivity to the drug.
* Hereditary or idiopathic angioedema.
## Adverse Effects
* **Common:** Cough (dry, persistent), dizziness, headache, fatigue, hyperkalemia.
* **Serious:** Angioedema (potentially life-threatening), acute kidney injury, hypotension, neutropenia, hepatotoxicity.
## Key Drug Interactions
* **Potassium-sparing diuretics, potassium supplements, spironolactone, losartan:** Increased risk of hyperkalemia.
* **NSAIDs, COX-2 inhibitors:** May reduce antihypertensive efficacy and increase risk of renal impairment.
* **Lithium:** ACE inhibitors can decrease renal clearance of lithium, increasing lithium toxicity risk.
* **Aliskiren, ARBs:** Increased risk of hyperkalemia, hypotension, and renal dysfunction. Avoid concurrent use, especially in high-risk patients.
* **Diuretics:** Increased risk of symptomatic hypotension.
## Monitoring
* **Blood Pressure:** Regularly monitor BP to assess efficacy and guide titration.
* **Renal Function:** Monitor serum creatinine and BUN, especially at initiation and with dose increases, or in patients with risk factors for renal dysfunction.
* **Electrolytes:** Monitor serum potassium, particularly in patients with renal impairment, diabetes, or those taking potassium-sparing diuretics or supplements.
* **Angioedema:** Educate patients to report any swelling of the face, lips, tongue, or throat immediately.
## Clinical Pearls
* The characteristic dry cough is thought to be due to bradykinin accumulation and typically resolves upon discontinuation.
* Angioedema can occur at any time during therapy and requires immediate discontinuation.
* Initiate at low doses and titrate slowly, especially in patients who are volume-depleted, have heart failure, or renal impairment.
* ACE inhibitors are generally preferred over ARBs for patients with established heart failure and reduced ejection fraction due to more robust evidence for improved mortality.
* Avoid use in pregnancy due to the risk of fetal harm.
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*This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
