Lisinopril
Also known as: Prinivil · Zestril · L-154826 · lisinoprilum · MK-521
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of heart failure | 0.5 mg/kg | PO | q12-24h | — | 🌎 NA |
| Adjunctive treatment of heart failure | 0.5 mg/kg | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of heart failure | 0.25-0.5 mg/kg | PO | q24h | — | 🌎 NA |
- Adjunctive treatment of heart failure: Highest recommended doses should be used unless not tolerated by patient.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of heart failure | 0.25-0.5 mg/kg | PO | q24h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor used primarily as a vasodilator in veterinary medicine for the management of congestive heart failure (CHF) and systemic hypertension.
Key clinical highlights:
- Directly Active: Unlike enalapril, lisinopril is not a prodrug and does not require hepatic biotransformation to become active, which may be advantageous in patients with concurrent severe hepatic dysfunction.
- Once-Daily Dosing: It typically offers a longer duration of action compared to some other ACE inhibitors, allowing for convenient once-daily dosing in many patients.
- Renal Protection: Often utilized to reduce proteinuria and help preserve renal function in patients with chronic kidney disease (CKD) or protein-losing nephropathies.
- Hemodynamic Benefits: Decreases total peripheral resistance, pulmonary vascular resistance, and pulmonary capillary wedge pressure while increasing cardiac output and exercise tolerance.
Clinical Pearl: While enalapril and benazepril are more commonly used and extensively studied in veterinary medicine, lisinopril serves as a viable, often less expensive alternative, particularly when once-daily dosing is preferred.
Mechanism of action
Lisinopril exerts its effects by interfering with the Renin-Angiotensin-Aldosterone System (RAAS).
- Mechanism: It competitively binds to and inhibits angiotensin-converting enzyme (ACE).
- Pathway: Angiotensin I → (blocked by ACE inhibition) → Decreased Angiotensin II.
- Physiological Effects:
- Vasodilation: Reduction in Angiotensin II (a potent vasoconstrictor) leads to decreased systemic vascular resistance (afterload) and venous tone (preload).
- Decreased Aldosterone: Lower Angiotensin II levels reduce the secretion of aldosterone from the adrenal cortex → decreased sodium and water retention.
- Bradykinin Preservation: ACE is also responsible for the breakdown of bradykinin. Inhibition leads to increased bradykinin levels, contributing to vasodilation (but also potentially causing a mild cough).
- Net Result: Decreased blood pressure, reduced cardiac workload, and decreased proteinuria due to efferent arteriolar vasodilation in the glomerulus.
Safety & warnings
Contraindications
- Known hypersensitivity to ACE inhibitors
- Pregnancy (especially 2nd and 3rd trimesters)
Adverse effects
- Anorexia
- Vomiting
- Diarrhea
- Lethargy or weakness
- Hypotension
- Renal dysfunction (azotemia)
- Hyperkalemia
- Cough (rare in animals compared to humans)
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 collagen vascular diseases (e.g., SLE). Patients with severe CHF should be monitored very closely for hypotension upon initiation of therapy. May cause a reversible decrease in localization and excretion of certain renal imaging agents.
Drug interactions
Possible increased risk for hypoglycemia; enhanced monitoring recommended.
Potential for increased hypotensive effects; reducing furosemide doses (by 25-50%) is often recommended when initiating ACE inhibitors in CHF.
Increased risk of hyperkalemia; enhanced monitoring of serum potassium recommended.
Potential for additive hypotensive effects.
Increased serum lithium levels possible; increased monitoring required.
May reduce the anti-hypertensive or positive hemodynamic effects of lisinopril; may increase the risk of acute renal failure.
Increased risk for hyperkalemia.
Monitoring
- Clinical signs of CHF (respiratory rate/effort, exercise tolerance)
- Blood pressure (especially upon initiation or dose changes)
- Serum electrolytes (specifically potassium)
- Renal panel (BUN, Creatinine)
- Urine protein
- Periodic CBC with differential
Pharmacokinetics
Half-life
Absorption
In dogs, bioavailability ranges from 25-50% with peak levels occurring about 4 hours after dosing.
Distribution
Distributed poorly into the CNS. Crosses the placenta. Unknown if distributed into maternal milk.
Metabolism
Lisinopril is directly active and does not need to be converted in the liver to an active metabolite.
Elimination
Half-lives are increased in patients with renal failure or severe CHF.
Overdose
The primary concern with overdosage is hypotension.
- Toxicity Thresholds: In dogs, the lowest dosage documented to cause hypotension is 27 mg/kg. Dosages below 20 mg/kg generally cause only mild signs (vomiting, lethargy). In cats, hypotension was noted at 4.9 mg/kg in a single case. In birds, mild somnolence occurred at 41 mg/kg.
- Clinical Signs: Hypotension, lethargy, vomiting, and tachycardia.
- Treatment: Recent overdoses should be managed using gut-emptying protocols when warranted. Supportive treatment with volume expansion using normal saline is recommended to correct blood pressure. Due to the drug's long duration of action, prolonged monitoring and treatment may be required.
Available products
Formulations
- Oral tablets
- Compounded oral suspension
Human-labeled
- Lisinopril Oral Tablets: 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg & 40 mg (Prinivil®, Zestril®, generic)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store tablets at room temperature in tight containers. A compounded oral suspension (1 mg/mL in Ora-Plus/Ora-Sweet) retains >95% potency for 91 days when stored at 4°C and protected from light.
Client information
- Do not abruptly stop or reduce therapy without your veterinarian's guidance.
- Can be given with or without food. Ensure your pet always has access to fresh water.
- Watch for weakness or fainting, which could be signs that your pet's blood pressure is too low.
- Contact your veterinarian immediately if vomiting or diarrhea persists, becomes severe, or if your pet's overall condition deteriorates.
- Keep out of reach of children and other pets.
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.