Benazepril is an angiotensin-converting enzyme (ACE) inhibitor widely used in feline medicine for the management of chronic kidney disease (CKD) and various forms of heart disease. Marketed under the veterinary brand name Fortekor, benazepril is one of the most commonly prescribed cardiovascular and renal medications in small animal practice. It is also available as the human generic Lotensin.
Overview
Benazepril works by inhibiting the angiotensin-converting enzyme, which is responsible for converting angiotensin I to angiotensin II — a potent vasoconstrictor. By blocking this conversion, benazepril reduces blood pressure, decreases glomerular pressure within the kidneys, and reduces proteinuria (protein loss in urine). In cats, benazepril is notable because approximately 85 percent of the active metabolite (benazeprilat) is eliminated via the biliary (liver) route, making it one of the few ACE inhibitors that does not rely primarily on renal excretion. This is especially advantageous in cats with compromised kidney function.
Uses
- Chronic kidney disease (CKD): Reduces proteinuria and intraglomerular pressure, potentially slowing CKD progression in cats.
- Hypertrophic cardiomyopathy (HCM): May be used to reduce afterload and manage congestive heart failure.
- Systemic hypertension: Used as an adjunct or alternative antihypertensive, often combined with amlodipine.
- Proteinuria: Helps reduce abnormal protein loss through the kidneys.
- Congestive heart failure (CHF): Part of multimodal heart failure management.
Dosage
| Parameter | Detail |
|---|---|
| Dose (cats) | 0.5–1.0 mg/kg orally once daily |
| Common tablet sizes | 2.5 mg, 5 mg (Fortekor); various sizes (generic) |
| Route | Oral |
| Frequency | Once daily |
| Monitoring | BUN, creatinine, electrolytes, blood pressure, urine protein |
Important dosing notes:
- Benazepril can be given with or without food.
- Kidney values and electrolytes should be rechecked 5 to 7 days after starting therapy and periodically thereafter.
- If creatinine rises significantly after starting benazepril, your veterinarian may adjust or discontinue the medication.
- Do not abruptly discontinue without veterinary guidance.
Side Effects
| Common Side Effects | Serious Side Effects (Contact Your Vet) |
|---|---|
| Mild decrease in appetite | Significant rise in kidney values (BUN/creatinine) |
| Occasional mild lethargy | Hyperkalemia (elevated potassium) |
| Mild GI upset (rare) | Hypotension (low blood pressure causing weakness or collapse) |
| Angioedema (facial swelling — rare) |
Most cats tolerate benazepril well. Side effects are uncommon at standard doses.
Drug Interactions
- NSAIDs (meloxicam, robenacoxib): May reduce the efficacy of benazepril and increase the risk of kidney injury.
- ARBs (telmisartan): Combining ACE inhibitors with ARBs increases the risk of hyperkalemia and acute kidney injury.
- Potassium supplements or potassium-sparing diuretics (spironolactone): Increased risk of hyperkalemia.
- Diuretics (furosemide): Additive blood pressure lowering; dose adjustment may be needed.
- Amlodipine: Commonly combined safely for blood pressure control, but monitoring is important.
Contraindications
- Do not use in cats with known hypersensitivity to ACE inhibitors.
- Avoid in cats with bilateral renal artery stenosis.
- Use with caution in severely dehydrated or hypovolemic cats (risk of acute kidney injury).
- Do not use in pregnant or lactating cats (ACE inhibitors are teratogenic).
Storage
- Store at room temperature (59–86 degrees F / 15–30 degrees C).
- Keep in the original container, protected from moisture.
- Keep out of reach of children and pets.
FAQ
Q: Is benazepril or telmisartan better for my cat’s kidney disease? A: Both are effective for managing proteinuria in CKD cats. Telmisartan (Semintra) is FDA-approved for feline CKD and comes as a palatable oral solution. Benazepril has a long track record and favorable hepatic elimination. Your veterinarian will choose based on your cat’s specific needs and response.
Q: Can benazepril cure kidney disease in cats? A: No. CKD is a progressive condition. Benazepril helps slow progression by reducing proteinuria and intraglomerular pressure, but it does not reverse existing kidney damage.
Q: How long does it take benazepril to work? A: Blood pressure effects begin within 1 to 2 hours of dosing. However, the full renoprotective benefits develop over days to weeks of consistent therapy.
Q: Should I stop benazepril if my cat’s kidney values go up slightly? A: A mild increase in creatinine (up to 30 percent) is expected and generally acceptable when starting ACE inhibitor therapy. Your veterinarian will monitor values and determine whether the medication should be continued.
This content is for informational purposes only and is not a substitute for professional veterinary advice. Always consult your veterinarian before starting, changing, or stopping any medication for your cat.