Ramipril — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	0.125-0.25 mg/kg	q24h	Duration: Chronic, adjust based on response Notes: Start at low end; titrate up to 0.5 mg/kg if needed. Monitor renal function and potassium.
Cat	PO	0.125-0.25 mg/kg	q24h	Duration: Chronic, adjust based on response Notes: Use cautiously in cats with renal disease; monitor blood pressure and renal parameters.
Horse	PO	Not established	Not established	Duration: Not established Notes: Limited data; not recommended without specialist guidance.
Cattle	PO	Not established	Not established	Duration: Not established Notes: Not indicated for food animals; no withdrawal times established.

Clinical Indications & Species Uses

General Indications

Management of hypertension, heart failure, and proteinuria in small animals

Dog (Canine)

Heart failure (congestive heart failure, mitral valve disease)
Hypertension
Protein-losing nephropathy (chronic kidney disease with proteinuria)

Cat (Feline)

Hypertension
Chronic kidney disease with proteinuria
Heart failure (less common)

Pharmacology & Mechanism of Action

Drug Class: ACE inhibitor | Pharmacological Group: Angiotensin-converting enzyme inhibitor

Mechanism of Action: Ramipril is a prodrug that is hydrolyzed in the liver to its active metabolite ramiprilat. Ramiprilat competitively inhibits angiotensin-converting enzyme (ACE), thereby blocking the conversion of angiotensin I to the potent vasoconstrictor angiotensin II. This leads to vasodilation, reduced aldosterone secretion, decreased sodium and water retention, and reduced preload and afterload. It also decreases degradation of bradykinin, which contributes to vasodilatory and potential beneficial effects on cardiac remodeling.

Pharmacodynamics: In veterinary patients, ramipril reduces systemic blood pressure, decreases cardiac workload, and improves cardiac output in heart failure. It also reduces proteinuria in chronic kidney disease by decreasing intraglomerular pressure and improving renal hemodynamics. The drug has been shown to attenuate left ventricular hypertrophy and improve survival in dogs with heart failure.

⚡ Pharmacokinetics Summary

Absorption: Ramipril is well absorbed after oral administration in dogs and cats, with peak plasma concentrations occurring within 1-2 hours. Food may delay absorption but does not significantly affect overall bioavailability.

Distribution: Ramipril is widely distributed, with high concentrations in the liver, kidneys, and lungs. It crosses the placenta and is excreted in milk. Volume of distribution is moderate.

Metabolism: Ramipril is extensively metabolized in the liver via ester hydrolysis to the active metabolite ramiprilat, which is further metabolized to inactive glucuronides. The conversion is rapid and extensive.

Excretion: Ramipril and its metabolites are primarily excreted via the kidneys (60%) and feces (40%). In animals with renal impairment, clearance is reduced, and dosage adjustment may be necessary.

Half-Life: Dogs: approximately 1-2 hours for ramipril and 4-6 hours for ramiprilat. Cats: approximately 1-2 hours for ramipril and 3-5 hours for ramiprilat.

Bioavailability: Oral bioavailability is approximately 44% in dogs and 50% in cats, due to first-pass metabolism.

Protein Binding: Ramipril is approximately 73% protein-bound, and ramiprilat is about 56% protein-bound in dogs.

Available Formulations & Strengths

Oral Tablet 1.25 mg, 2.5 mg, 5 mg, 10 mg (PO)

Oral Capsule 2.5 mg, 5 mg, 10 mg (PO)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to ramipril or other ACE inhibitors
History of angioedema
Pregnancy (especially second and third trimester) and lactation
Severe renal impairment (unless used for renal protective effects with careful monitoring)
Hyperkalemia
Concurrent use with aliskiren (in humans; not relevant in vet medicine but caution)

Warnings & Clinical Precautions:

Monitor renal function and serum potassium within 1-2 weeks after initiation or dose increase.
Use with caution in animals with pre-existing renal disease; may cause transient worsening of renal function.
May cause hypotension, especially in volume-depleted animals; ensure adequate hydration.
Use with caution in animals with severe heart failure; may require dose adjustment.
Do not use in pregnant animals; can cause fetal toxicity.
In food animals, extra-label use is prohibited; no withdrawal times established.

Adverse Effects & Reactions

Common:

Hypotension
Dizziness or weakness
Gastrointestinal upset (vomiting, diarrhea)
Cough (rare in animals but possible)
Increased serum creatinine and potassium

Serious / Severe:

Acute renal failure
Hyperkalemia
Angioedema
Severe hypotension
Bone marrow suppression (rare)

Rare:

Hepatotoxicity
Pancreatitis
Blood dyscrasias
Alopecia

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Potassium-sparing diuretics (spironolactone, triamterene)	Increased risk of hyperkalemia	High
Nonsteroidal anti-inflammatory drugs (NSAIDs)	Reduced antihypertensive effect and increased risk of renal dysfunction	Moderate
Diuretics (furosemide)	Additive hypotension and risk of renal impairment	Moderate
Other antihypertensives (e.g., amlodipine)	Additive hypotensive effect	Moderate
Lithium	Increased lithium levels and toxicity risk	High

Overdose & Toxicity Management

Signs of Toxicity:

Severe hypotension
Renal failure
Hyperkalemia
Bradycardia
Lethargy
Collapse

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Induce emesis if recent ingestion (within 1-2 hours) and activated charcoal. Administer IV fluids to maintain blood pressure and renal perfusion. Correct hyperkalemia with insulin/dextrose, calcium gluconate, or sodium bicarbonate as needed. In severe cases, consider hemodialysis. Monitor ECG and renal function.

Food Animal Withdrawal Times

Not approved for food animals; extra-label use prohibited. No withdrawal times established.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (20-25°C, 68-77°F)

Handling & Special Conditions: Protect from moisture; keep in tightly closed container.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs in some countries (e.g., Europe) for heart failure; not FDA-approved for veterinary use in the US, but may be used extra-label.

Extra-Label (Off-Label) Use: In the US, extra-label use in food animals is prohibited under AMDUCA if an approved drug exists for that species/indication. For companion animals, extra-label use is permitted with appropriate veterinary oversight.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Ramipril is a valuable ACE inhibitor for managing heart failure and hypertension in dogs and cats. It is often preferred for its once-daily dosing and long duration of action. In dogs with mitral valve disease, it improves quality of life and survival. In cats with chronic kidney disease and proteinuria, it reduces protein loss and may slow disease progression. Always start at the low end of the dose range and titrate based on clinical response and tolerability. Monitor blood pressure, renal function, and electrolytes, especially during the first weeks of therapy. Use with caution in animals with renal impairment, and avoid concurrent use with potassium supplements or potassium-sparing diuretics unless closely monitored. Client education should include signs of hypotension (weakness, lethargy) and the importance of regular veterinary check-ups.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)