ACE Inhibitors

Key Points

• ACE inhibitors block the conversion of angiotensin I → angiotensin II, reducing vasoconstriction, aldosterone release, and blood pressure.
• Used for hypertension, heart failure, post-MI cardioprotection, and diabetic nephropathy.
• Signature adverse effect: persistent dry cough (bradykinin accumulation) — occurs in up to 15% of patients; switch to ARB if intolerable.
• Hyperkalemia risk — avoid potassium supplements and potassium-sparing diuretics; monitor serum potassium closely.
• Absolute contraindication in pregnancy (boxed warning): causes fetal harm and death; women of childbearing age must use effective contraception.
• Pediatric congenital-cardiac use may include selected valve-regurgitation lesions, left-to-right shunt defects, and heart-failure pathways to reduce afterload and remodeling stress.

Mechanism of Action

The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure and fluid balance:

1. Renin (from kidneys) converts angiotensinogen → Angiotensin I
2. ACE (angiotensin-converting enzyme) converts Angiotensin I → Angiotensin II
3. Angiotensin II causes vasoconstriction + aldosterone release → sodium/water retention → elevated BP

ACE inhibitors block step 2, preventing angiotensin II formation:

• Vasodilation → ↓ systemic vascular resistance → ↓ blood pressure
• ↓ Aldosterone → ↑ sodium and water excretion → ↓ preload and fluid volume

Bradykinin (normally degraded by ACE) accumulates → causes the characteristic dry cough.

Common ACE Inhibitors

Drug	Route	Typical Dose
Lisinopril (Zestril)	PO	10–40 mg once daily
Enalapril (Vasotec)	PO, IV	5–40 mg/day in 1–2 doses
Captopril (Capoten)	PO	25–150 mg 2–3 times daily
Benazepril (Lotensin)	PO	10–40 mg once daily
Ramipril (Altace)	PO	2.5–20 mg/day in 1–2 doses

Indications

• Hypertension — first-line therapy (especially in patients with diabetes or CKD)
• Heart failure (reduced ejection fraction) — reduces mortality and hospitalizations
• Post-myocardial infarction — cardioprotection and remodeling prevention
• Diabetic nephropathy — slows progression of kidney damage by reducing intraglomerular pressure
• Selected pediatric congenital-heart pathways — afterload reduction in mitral/aortic regurgitation and left-to-right shunt burden when specialist-directed

Nursing Assessment

NCLEX Focus

Two signature ACE inhibitor adverse effects to know:

1. Dry, persistent cough (bradykinin effect) — does NOT resolve with dose reduction; switch to ARB (angiotensin receptor blocker) if intolerable
2. Angioedema — rare but life-threatening swelling of face, lips, tongue, or throat — discontinue immediately and treat as emergency

Pre-administration:

• Assess blood pressure and pulse — hold and notify provider if significantly hypotensive
• Review potassium level — ACE inhibitors cause potassium retention (hyperkalemia risk)
• Assess pregnancy status — absolutely contraindicated in pregnancy (boxed warning)
• Assess renal function — use with caution in renal impairment; may worsen renal function

Contraindications:

• Pregnancy (boxed warning — fetal harm/death)
• History of ACE inhibitor-associated angioedema or hereditary angioedema
• Concurrent use with aliskiren in diabetic patients (severe hypotension/renal impairment risk)
• Bilateral renal artery stenosis

Nursing Interventions

Monitoring parameters:

• Blood pressure (especially first dose — first-dose hypotension risk, especially in volume-depleted patients)
• Serum potassium — hyperkalemia risk; avoid potassium supplements, salt substitutes, and potassium-sparing diuretics
• Renal function (BUN/creatinine) — mild elevation expected; significant rise requires provider notification
• Signs of angioedema: sudden facial or airway swelling — emergency; discontinue and call rapid response

Adverse effects to monitor:

• Dry persistent cough — most common; report to provider; may require medication change to ARB
• Hypotension — especially first dose and in dehydrated patients; check BP before each dose
• Hyperkalemia — fatigue, muscle weakness, cardiac dysrhythmias
• Angioedema — rare but life-threatening (swelling of face, lips, throat)
• Altered taste sensation — typically resolves within 2–3 months

Angioedema Emergency

Any report of sudden swelling of the face, lips, tongue, or throat in a patient taking an ACE inhibitor requires immediate discontinuation of the medication and emergency treatment. Airway compromise can occur rapidly.

Patient education:

• Take medication at the same time each day; do not stop abruptly
• Report persistent dry cough to provider — alternative medication may be needed
• Avoid potassium supplements and salt substitutes (most contain potassium chloride)
• Rise slowly from sitting or lying position — orthostatic hypotension risk
• Women of childbearing age: use effective contraception; report pregnancy immediately — medication must be stopped immediately
• Report any facial swelling, difficulty breathing, or swallowing immediately

Related Concepts

• hypertension-assessment-and-management — ACE inhibitors as first-line antihypertensive therapy, especially in diabetes and CKD.
• heart-failure — ACE inhibitors reduce mortality and prevent cardiac remodeling in systolic heart failure.
• kidney-disease — Renoprotective effects in diabetic nephropathy; monitoring for worsening renal function.
• potassium-balance-disorders — Hyperkalemia risk from ACE inhibitor-induced aldosterone suppression.
• antihypertensives — ACE inhibitors in context of antihypertensive drug classes.
• high-alert-medications — ACE inhibitor-associated risks (angioedema, hypotension, teratogenicity) requiring monitoring.

Self-Check

1. A client taking lisinopril reports a persistent dry cough for 3 weeks. What is the most likely cause, and what nursing action is appropriate?
2. A client on captopril has a serum potassium of 5.8 mEq/L. What factors may have contributed to this, and what nursing interventions are indicated?
3. Why are ACE inhibitors absolutely contraindicated in pregnancy, and what teaching should the nurse provide to a woman of childbearing age starting lisinopril?