Benazepril

Benazepril is an angiotensin-converting enzyme inhibitor used in veterinary cardiovascular disease and proteinuric kidney disease. It is administered as a prodrug and converted to the active metabolite benazeprilat. Its effects include reduction of angiotensin-mediated vascular tone and glomerular pressure rather than direct stimulation of cardiac contraction.

Dual biliary and renal elimination distinguishes it from some related drugs. Its clinical role is nevertheless patient- and disease-specific: reduction of proteinuria does not establish a survival benefit in every chronic kidney disease population, and it is not usually sufficient as the sole treatment for marked feline hypertension.

Group

ACE inhibitor

Mechanism of Action

After conversion to benazeprilat, the drug inhibits angiotensin-converting enzyme and decreases conversion of angiotensin I to angiotensin II. Less angiotensin II reduces vasoconstrictor drive and aldosterone stimulation, which can lower vascular resistance and reduce sodium- and water-retaining influences.

ACE also participates in degradation of bradykinin, so inhibition can increase vasodilating kinin activity. These combined effects can reduce cardiac loading conditions and oppose maladaptive renin–angiotensin–aldosterone activation in heart failure. Benazepril is not itself a rapid decongestant or positive inotrope.

Within the kidney, reduced angiotensin-mediated efferent arteriolar tone can lower intraglomerular pressure and decrease protein leakage. This antiproteinuric mechanism explains its use in glomerular disease, while also explaining why changes in filtration can occur when renal perfusion depends on angiotensin-mediated support.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Cardiovascular disease and proteinuria	0.25–0.5 mg/kg	PO	Every 12–24 h	A common starting regimen is 0.5 mg/kg once daily. Titrate according to clinical response.
Cardiovascular disease and proteinuria	0.5 mg/kg	PO	Every 24 h	Common once-daily regimen.
Dose escalation	Reference only	PO		If needed, increase by 0.5 mg/kg increments to no more than 2 mg/kg every 24 hours orally; reassess blood pressure, renal function and electrolytes.
Congestive heart failure	0.25–0.5 mg/kg	PO	Every 24 h
Congestive heart failure	0.25–0.5 mg/kg	PO	Every 12–24 h
Hypertension and proteinuria	0.25–1 mg/kg	PO	Every 12–24 h	Start lower with preexisting azotemia and monitor renal indices.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Systemic hypertension	0.5–1 mg/kg	PO	Every 24 h
Systemic hypertension	2.5 mg/animal	PO	Every 24 h	Alternative fixed dose only for cats weighing up to 5 kg.
Chronic kidney disease with proteinuria	0.25–0.5 mg/kg	PO	Every 24 h
Congestive heart failure	0.25–0.5 mg/kg	PO	Every 24 h
Congestive heart failure	0.25–0.5 mg/kg	PO	Every 12–24 h
Hypertension and proteinuria	0.25–1 mg/kg	PO	Every 12–24 h
Chronic kidney disease with proteinuria	0.25–0.5 mg/kg	PO	Every 12–24 h

Indications

Adjunctive treatment of canine congestive heart failure within a multidrug plan.
Reduction of persistent proteinuria associated with glomerular disease or chronic kidney disease in dogs and selected cats.
Selected systemic hypertension cases where ACE inhibition contributes to blood-pressure control.

Contraindications

Pregnancy.
ACE-inhibitor hypersensitivity.
Use cautiously with sodium depletion, severe heart failure, vascular insufficiency, hematologic abnormalities or systemic lupus erythematosus.

Interactions

Other hypotensive agents and diuretics can increase hypotension or azotemia.
NSAIDs may reduce the vasodilator response.
Spironolactone can increase potassium.
Lithium concentrations may rise.
Potassium supplements increase hyperkalemia risk.

Adverse effects

Hypotension
Azotemia
Hyperkalemia
Anorexia, vomiting or diarrhea

Preparations

Preparation	Form	Strength	Route
Benazepril 5 mg tablet	Tablet	5 mg / tablet	PO
Benazepril 10 mg tablet	Tablet	10 mg / tablet	PO
Benazepril 20 mg tablet	Tablet	20 mg / tablet	PO
Benazepril 40 mg tablet	Tablet	40 mg / tablet	PO

Monitoring and Administration

Measure blood pressure, creatinine and electrolytes 3–7 days after starting and periodically thereafter, especially with high-dose diuretics.

A survival benefit in feline CKD has not been established. Benazepril is not a preferred primary agent for spontaneous feline hypertension; occult canine mitral disease has not shown benefit.

Protect tablets from light and moisture at room temperature.

Follow urine protein, blood pressure and heart-failure signs alongside creatinine, BUN and electrolytes. Protect tablets from moisture and keep below 30°C.