enalapril

ACE inhibitor· Brands: Vasotec, Renitec, InnovacePO

Mechanism of action

Angiotensin-converting enzyme (ACE) inhibitors block the conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion, leading to decreased blood pressure and reduced preload and afterload.

Pharmacokinetics

Enalapril is a prodrug that is hydrolyzed to the active metabolite enalaprilat. It is well absorbed orally, with peak serum concentrations occurring 1 hour after administration. The active form reaches peak levels in 3-4 hours. Elimination is primarily renal, with a half-life of approximately 11 hours, allowing once-daily dosing in most patients.

Indications & dosing

Hypertension

Starting dose 5 mg once daily; usual maintenance 10-20 mg once daily. Titrate according to response.

adult · PO: 5–20 mg OD · Starting dose 5 mg once daily; usual maintenance 10-20 mg once daily. Titrate according to response.

Heart failure

Initial dose 2.5 mg twice daily; increase gradually to target 10 mg twice daily as tolerated.

adult · PO: 2.5–10 mg BD · Initial dose 2.5 mg twice daily; increase gradually to target 10 mg twice daily as tolerated.

Asymptomatic left ventricular dysfunction

To reduce the risk of heart failure development. Start at 2.5 mg twice daily, titrate to 10 mg twice daily.

adult · PO: 2.5–10 mg BD · To reduce the risk of heart failure development. Start at 2.5 mg twice daily, titrate to 10 mg twice daily.

Diabetic nephropathyoff-label

Used to reduce albuminuria in patients with diabetes. Individualise dose; monitor renal function.

adult · PO: 10–20 mg OD · Used to reduce albuminuria in patients with diabetes. Individualise dose; monitor renal function.

Hypertension (paediatric)

Initial dose 0.08 mg/kg once daily; maximum 5 mg. Adjust according to response.

pediatric · PO: 0.08 mg/kg OD · Initial dose 0.08 mg/kg once daily; maximum 5 mg. Adjust according to response.

Contraindications & precautions

Pregnancy (particularly 2nd and 3rd trimester) · Can cause fetal harm; use alternative if possible.
History of angioedema (e.g. from previous ACE inhibitor or hereditary) · Risk of life-threatening airway obstruction.
Bilateral renal artery stenosis · Can worsen renal function; consider alternative.
Known hypersensitivity to enalapril or other ACE inhibitors · Cross-reactivity possible.
Monitor renal function and serum potassium, especially in patients with renal impairment or taking potassium-sparing diuretics.
Initiate at low dose and titrate slowly in patients with heart failure or those at risk of first-dose hypotension.
Caution in patients with aortic stenosis or hypertrophic cardiomyopathy, as afterload reduction may worsen symptoms.
Advise patients to report any swelling of face, lips, or tongue immediately, as this indicates angioedema.
Use with caution in patients with systemic sclerosis (scleroderma) or other conditions predisposing to renal impairment.

Adverse effects

Dry persistent cough
Dizziness
Headache
Severe hypotension (first dose)serious
Hyperkalaemiaserious
Angioedema (including laryngeal oedema)serious
Renal impairment (increased creatinine, proteinuria)serious
Taste disturbance

Renal & hepatic adjustment

eGFR 30–59: Reduce initial dose to 5 mg once daily; titrate cautiously.
eGFR 15–29: Reduce initial dose to 2.5 mg once daily; monitor renal function and potassium.
eGFR 0–14: Use with caution under specialist supervision; consider alternative agent.

Monitoring, pregnancy & toxicity

Blood pressure · Before starting, after each dose increase, and during maintenance.
Serum creatinine and eGFR · Before starting, 1 to 2 weeks after starting or after a dose increase, then periodically.
Serum potassium · Before starting, 1 to 2 weeks after starting or after a dose increase, then periodically.
Signs of angioedema · Monitor for swelling of face, lips, tongue, or throat; advise patient to seek urgent help if this occurs.
Dry persistent cough · Ask about new or worsening cough at follow-up visits.
Pregnancy: Enalapril is contraindicated in pregnancy. Exposure in the second and third trimester can cause fetal renal damage, oligohydramnios, and neonatal complications including hypotension and renal failure. Discontinue before conception or as soon as pregnancy is confirmed; switch to an alternative antihypertensive appropriate for pregnancy.
Toxicity: Hypotension (with dizziness, syncope) · Lay patient flat, give IV 0.9% sodium chloride; monitor blood pressure; consider vasopressors if refractory.
Toxicity: Hyperkalaemia · Monitor serum potassium; withhold drug; treat with insulin-dextrose, sodium bicarbonate, or calcium gluconate as per local guidelines; consider dialysis.
Toxicity: Acute renal impairment (rising creatinine) · Check volume status, stop drug, treat dehydration; monitor urine output and renal function.
Toxicity: Angioedema (swelling of face, lips, tongue, throat) · Discontinue drug immediately; give oxygen, adrenaline, and supportive care; do not give further ACE inhibitors.

Clinical notes

Enalapril is used for hypertension, heart failure, and to improve survival after myocardial infarction. It may cause a dry persistent cough, hyperkalaemia, and angioedema. Initiate low dose in patients with renal impairment or those on diuretics. Monitor renal function and potassium levels. Avoid in pregnancy and in patients with a history of angioedema.

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BNF; local formulary