Imidapril
Imidapril hydrochloride
Also known as: Prilium · Imidapril hydrochloride · Imidaprilum
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 |
|---|---|---|---|---|---|
| Congestive heart failure, proteinuria, or hypertension | 0.25 mg/kg | PO | q24h | — | 🌍 EU |
- Congestive heart failure, proteinuria, or hypertension: For dogs weighing >4 kg.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Cardiac disease or proteinuria | 0.5 mg/kg | PO | q24h | — | 🌍 EU |
- Cardiac disease or proteinuria: Anecdotal dose; no data available.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Imidapril is an angiotensin-converting enzyme (ACE) inhibitor primarily used in veterinary medicine for the management of congestive heart failure (CHF) caused by mitral valve regurgitation or dilated cardiomyopathy in dogs. It is often used in conjunction with diuretics, pimobendan, or spironolactone for maximum efficacy. Additionally, it is utilized to manage proteinuria associated with chronic renal insufficiency, glomerular disorders, and protein-losing nephropathies, and may help reduce blood pressure in cases of hypertension.
Clinical Warning: ACE inhibitors are more likely to cause or exacerbate prerenal azotemia in hypotensive animals and those with poor renal perfusion (e.g., acute, oliguric renal failure). Use with extreme caution if hypotension, hyponatremia, or outflow tract obstruction are present.
Clinical Pearl: While primarily licensed for dogs, the use of ACE inhibitors in cats with cardiac disease stems from extrapolation of theoretical benefits and studies in other species.
Mechanism of action
Imidapril acts by competitively inhibiting the angiotensin-converting enzyme (ACE).
- Angiotensin I → (ACE inhibition) → Decreased Angiotensin II production.
- Inhibits the breakdown of bradykinin (a potent vasodilator).
The overall cardiovascular effect is a reduction in preload and afterload via venodilation and arteriodilation, decreased salt and water retention via reduced aldosterone production, and inhibition of angiotensin-aldosterone-mediated cardiac and vascular remodeling.
In the kidneys, it causes efferent arteriolar dilation, which reduces intraglomerular pressure and glomerular filtration, thereby decreasing proteinuria.
Safety & warnings
Contraindications
- Acute renal failure
- Congenital heart disease
- Hemodynamically relevant stenoses (e.g., aortic stenosis)
- Obstructive hypertrophic cardiomyopathy
- Hypovolemia
- Breeding, pregnant, or lactating bitches
- Dogs weighing < 4 kg (safety not established)
Adverse effects
- Hypotension
- Hyperkalemia
- Azotemia
- Anorexia (rare)
- Vomiting (rare)
- Diarrhea (rare)
Precautions
Regular monitoring of blood pressure, serum creatinine, urea, and electrolytes is strongly recommended during ACE inhibitor treatment. Dosage should be reduced if there are clinical signs of hypotension (e.g., weakness, disorientation). Use cautiously in patients with hyponatremia or outflow tract obstructions.
Drug interactions
Could result in hyperkalemia, though in practice, spironolactone and ACE inhibitors appear safe to use concurrently.
Increased risk of hyperkalemia.
Increased risk of nephrotoxicity and decreased clinical efficacy of the ACE inhibitor.
Increased risk of hypotension.
Increased risk of hypotension.
Increased risk of hypotension when combined with negative inotropes.
Monitoring
- Blood pressure
- Serum creatinine and BUN
- Serum electrolytes (especially potassium and sodium)
- Clinical signs of hypotension (weakness, syncope)
Pharmacokinetics
Metabolism
Imidapril is a prodrug that is metabolized in the liver to its active metabolite, imidaprilat.
Overdose
Doses of up to 5 mg/kg/day have been well tolerated in healthy dogs. If overdosage occurs, monitor closely for signs of hypotension (weakness, lethargy, disorientation). If hypotension occurs, supportive care including intravenous fluids may be required.
Available products
Formulations
- 75 mg powder for oral solution
- 150 mg powder for oral solution
Veterinary
- Prilium 75 mg powder for oral solution
- Prilium 150 mg powder for oral solution
Regulatory status
POM-V
POM-V
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store the unmixed powder at room temperature. Once reconstituted with water, the oral solution should be stored in the refrigerator (2-8°C) and used within the timeframe specified by the manufacturer (typically 77 days).
Client information
Purpose: Imidapril helps your pet's heart pump more easily by relaxing the blood vessels. It is also used to protect the kidneys from losing too much protein in certain kidney diseases.
Administration: Give exactly as prescribed by your veterinarian. It is typically given as a liquid once a day.
What to watch for: Contact your veterinarian if your pet seems unusually tired, weak, dizzy, or loses their appetite. These could be signs that their blood pressure has dropped too low.
Monitoring: Your vet will need to check your pet's blood pressure and run blood tests periodically to ensure their kidneys are handling the medication well and that their potassium levels remain safe.
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.