Enalapril
Enalapril maleate / Enalaprilat
Also known as: Enacard · Vasotec · Glioten · Lotrial · Pres · Renitec · Reniten · Xanef · Enalapril maleate · Enalaprilat · MK-421 · MK-422 · Enalaprilic acid
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceAdjunctive therapy for heart failure (extra-label) — Dilated cardiomyopathy
- q24-48h
NA
Governing clinical context (3)
- Adjunctive therapy for heart failure (extra-label):
- ■ This medicine is usually well tolerated but vomiting and diarrhea can occur. It may be given with or without food. If your animal vomits, stops eating, or acts sick after getting enalapril on an empty stomach, give with food or a small treat to see if this helps. If vomiting continues, contact your veterinarian.
- Enalapril tablets should be stored at temperatures less than 30°C (86°F) in tight containers. Enalapril solution should be stored under refrigeration at 2°C to 8°C (36°F-46°F) in tightly closed containers; avoid freezing or excessive heat. Enalapril solution may be stored at room temperature (20°C-25°C [68°F-77°F]) but must be discarded after 60 days.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Enalapril is a widely used Angiotensin-Converting Enzyme (ACE) inhibitor in veterinary medicine. It acts as a balanced vasodilator, reducing both preload and afterload, making it a cornerstone in the management of congestive heart failure (CHF) in dogs and cats, often used alongside pimobendan and furosemide.
Beyond its cardiovascular applications, enalapril is highly valued for its renoprotective properties. By decreasing efferent glomerular arteriolar resistance, it effectively reduces intraglomerular pressure and proteinuria, making it a standard adjunctive treatment for chronic kidney disease (CKD) and protein-losing nephropathies (PLN).
Clinical Pearl: Enalapril is a prodrug that requires hepatic biotransformation into its active metabolite, enalaprilat. In patients with severe hepatic dysfunction, conversion may be impaired, and alternative therapies might be considered. Because it is primarily excreted by the kidneys, dosage adjustments are often necessary in patients with significant renal impairment.
Mechanism of action
Enalapril is a prodrug converted in the liver to the active compound enalaprilat. Enalaprilat competitively binds to and inhibits Angiotensin-Converting Enzyme (ACE).
- RAAS Inhibition: Prevents the conversion of inactive Angiotensin-I → active Angiotensin-II (a potent vasoconstrictor).
- Vasodilation: Decreased Angiotensin-II leads to reduced total peripheral resistance, pulmonary vascular resistance, and blood pressure (↓ afterload and preload).
- Aldosterone Reduction: Lower Angiotensin-II levels reduce the secretion of aldosterone from the adrenal cortex, leading to decreased sodium and water retention, while mildly increasing potassium retention.
- Renal Hemodynamics: Preferentially dilates the efferent arteriole of the glomerulus. This reduces intraglomerular hydrostatic pressure, thereby decreasing the filtration of proteins into the urine (anti-proteinuric effect) and slowing the progression of glomerular disease.
Safety & warnings
Contraindications
- Hypersensitivity to ACE inhibitors
- Pregnancy (Category C in first trimester, Category D in second/third trimesters due to fetal kidney developmental risks)
Adverse effects
- Anorexia
- Vomiting
- Diarrhea
- Weakness
- Hypotension
- Renal dysfunction
- Hyperkalemia
- Lethargy (especially in cats)
- Inappetence
Precautions
Use with caution and close supervision in patients with renal insufficiency (doses may need to be reduced). Use cautiously in patients with hyponatremia or sodium depletion, coronary or cerebrovascular insufficiency, preexisting hematologic abnormalities, or a collagen vascular disease (e.g., SLE). Patients with severe CHF should be monitored very closely upon initiation of therapy for acute hypotension or acute kidney injury. Safe use during nursing cannot be assumed as it is excreted into milk.
Drug interactions
Possible increased risk for hypoglycemia; enhanced monitoring recommended
Potential for increased hypotensive effects; furosemide doses may need reduction (by 25-50%) when adding enalapril
Increased hyperkalemic effects; enhanced monitoring of serum potassium recommended
Potential for increased hypotensive effect
Increased serum lithium levels possible; increased monitoring required
May reduce the anti-hypertensive or positive hemodynamic effects of enalapril; may increase risk for reduced renal function
Increased risk for hyperkalemia
Monitoring
- Clinical signs of CHF (respiratory rate/effort, exercise tolerance)
- Serum electrolytes (especially potassium)
- Renal panel (creatinine, BUN)
- Urine protein (UPC ratio)
- CBC with differential (periodic)
- Blood pressure (especially if treating hypertension or if clinical signs of hypotension arise)
Pharmacokinetics
Half-life
Absorption
In humans, enalapril is well absorbed after oral administration (approx 60% bioavailable), but enalaprilat is not.
Distribution
Distributed poorly into the CNS. Crosses the placenta and is distributed into milk in trace amounts.
Metabolism
Enalapril is a prodrug converted in the liver to the active compound enalaprilat.
Elimination
In dogs, approximately 95% of enalaprilat is cleared via renal routes. Reduced renal function can impact elimination rates.
Overdose
In dogs, a dose of 200 mg/kg was lethal, but 100 mg/kg was not.
- Primary Concern: Severe hypotension.
- Treatment: Supportive treatment with volume expansion using normal saline is recommended to correct blood pressure.
- Monitoring: Because of the drug's long duration of action, prolonged monitoring and treatment may be required.
- Decontamination: Recent overdoses should be managed by using gut emptying protocols when warranted.
Available products
Formulations
- Tablets
- Injection (Enalaprilat for IV use)
- Oral suspension (compounded)
Veterinary
- Enalapril Maleate Tablets: 1 mg, 2.5 mg, 5 mg, 10 mg, & 20 mg (Enacard)
Human-labeled
- Enalapril Maleate Tablets: 2.5 mg, 5 mg, 10 mg & 20 mg (Vasotec, generic)
- Enalaprilat Injection: equivalent to 1.25 mg/mL in 1 mL & 2 mL vials (generic)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Commercially available tablets should be stored at temperatures less than 30°C in tight containers. Enalaprilat injection should be stored at <30°C; after dilution with D5W, normal saline, or D5 in lactated Ringer's, it is stable for up to 24 hours at room temperature. Compounded oral suspensions should be protected from light.
Client information
Enalapril is used to help your pet's heart pump more easily or to protect their kidneys from losing protein.
- Administration: May be given with or without food. If your pet vomits after receiving it on an empty stomach, try giving it with a small treat or meal.
- Consistency is Key: Do not abruptly stop or reduce therapy without your veterinarian's approval, as this could cause a sudden worsening of heart or kidney disease.
- What to Watch For: Contact your veterinarian if vomiting or diarrhea persist or are severe.
- Signs of Low Blood Pressure: Watch for weakness, lethargy, stumbling, or fainting. If these occur, contact your vet immediately, as the dose may need adjustment.
- Monitoring: Your vet will need to check your pet's bloodwork (kidney values and potassium) and blood pressure regularly while on this medication.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.