Benazepril

Introduction Overview

Generic Name

benazepril

Brand Name

Lotensin

Dosage Form

oral tablet (5 mg, 10 mg, 20 mg, 40 mg)

Drug Class

Angiotensin Converting Enzyme Inhibitors (ACE inhibitors)

Pharmacokinetics

Absorption

Benazepril is rapidly absorbed following oral administration with peak plasma concentrations of its active metabolite, benazeprilat, occurring approximately 1 to 2 hours post-dose. The absolute bioavailability of benazepril is estimated to be around 37%. Food does not significantly affect its absorption, allowing administration without regard to meals. The drug undergoes extensive first-pass metabolism, converting quickly to benazeprilat, the active ACE inhibitor form, which is responsible for its pharmacologic effects.

Distribution

Benazeprilat distributes widely in body tissues. The volume of distribution is approximately 200 liters, reflecting significant tissue binding. Benazeprilat exhibits low plasma protein binding (~96%) primarily to albumin. The drug achieves therapeutic concentrations within cardiovascular tissues which is central to its efficacy in modulating the renin-angiotensin system.

Metabolism

Benazepril is a prodrug that undergoes hepatic metabolism by ester hydrolysis to the pharmacologically active benazeprilat. This biotransformation occurs concomitant with absorption and first-pass metabolism. Benazepril itself is pharmacologically inactive. The extensive hepatic conversion ensures effective systemic ACE inhibition. Minimal involvement of cytochrome P450 enzymes reduces potential for many metabolic drug interactions.

Elimination

Benazeprilat is predominantly eliminated renally, with approximately 95% of the administered dose excreted in the urine as unchanged benazeprilat and its metabolites. The elimination half-life of benazeprilat is approximately 10 to 11 hours, supporting once-daily dosing. Renal impairment significantly decreases clearance, requiring dosage adjustments; hepatic impairment has minimal effects on elimination.

Dosage Forms

Adults

Benazepril is available in oral tablet forms of 5 mg, 10 mg, 20 mg, and 40 mg. For adult hypertension, the usual initial dose is 10 mg daily when used without a diuretic, or 5 mg daily if combined with a diuretic. Maintenance doses range from 20 mg to 40 mg daily, administered as a single or divided dose. Doses up to 80 mg daily have been used clinically with close monitoring for efficacy and side effects.

Adolescents

Benazepril is indicated for hypertension in children aged 6 years and older. The recommended initial pediatric dosage is approximately 0.2 mg/kg orally once daily as monotherapy, with titration up to 0.6 mg/kg or a maximum of 40 mg daily. Dosage must be carefully calculated based on weight, and liquid formulations or tablet suspensions may be compounded if tablets are unsuitable for precise dosing.

Special Populations

In patients with renal impairment, dosage adjustments are necessary due to reduced clearance and increased risk of adverse effects, particularly hyperkalemia and hypotension. The drug should be used cautiously in hepatic impairment, although no specific dosing adjustments are established. Elderly patients may have heightened sensitivity and require careful dose titration. Benazepril is contraindicated during pregnancy and breastfeeding due to potential fetal harm.

Mechanism Of Action

Benazepril is an angiotensin-converting enzyme (ACE) inhibitor that exerts its effect by competitively inhibiting ACE, the enzyme responsible for converting angiotensin I to the potent vasoconstrictor angiotensin II. By blocking this conversion, benazepril decreases angiotensin II levels, leading to vasodilation, reduced aldosterone secretion, and decreased sodium and water retention. This results in lowered systemic vascular resistance and blood pressure.

At the cellular level, the inhibition of ACE also decreases the breakdown of bradykinin, a vasodilatory peptide, which enhances nitric oxide and prostacyclin production. This contributes to further vasodilation and improved endothelial function. The decreased angiotensin II also reduces sympathetic nervous system activity and suppresses remodeling processes within the cardiovascular system.

Clinically, these actions reduce preload and afterload on the heart, alleviating hypertension and reducing stress on cardiac tissues. By lowering aldosterone-mediated sodium retention, benazepril decreases volume overload. Comparative studies show similarity with other ACE inhibitors, but benazepril’s high affinity and prolonged duration of action contribute to its efficacy and once-daily dosing.

Research has demonstrated benazepril’s beneficial effects on renal protection in diabetic nephropathy and heart failure, attributable to its modulation of the renin-angiotensin-aldosterone system and anti-fibrotic properties, positioning it as a key agent in cardiovascular and renal therapeutics.

Pharmacological Actions

Inhibits angiotensin converting enzyme (ACE), reducing conversion of angiotensin I to angiotensin II
Decreases vasoconstriction, resulting in systemic arterial vasodilation
Reduces aldosterone secretion leading to decreased sodium and water retention
Enhances bradykinin levels promoting vasodilation through nitric oxide and prostacyclin
Lowers blood pressure by decreasing systemic vascular resistance
Reduces cardiac preload and afterload, improving cardiac function
Modulates sympathetic nervous system activity, reducing vascular resistance
Exerts renal protective effects by decreasing glomerular hypertension
Has anti-fibrotic effects on cardiovascular and renal tissues
Improves endothelial function by enhancing vasodilatory pathways
Decreases aldosterone-related myocardial and vascular remodeling

Therapeutic Clinical Uses

Treatment of hypertension in adults and pediatric patients aged 6 years and older
Used as monotherapy or in combination with other antihypertensive agents
Management of heart failure (off-label and in clinical practice)
Treatment adjunct in diabetic nephropathy to reduce progression of renal disease
Reduction of cardiovascular morbidity in patients at high risk for cardiac events
May be used post-myocardial infarction to improve cardiac remodeling (off-label)
Improvement of left ventricular function in patients with left ventricular dysfunction
Off-label use in proteinuric kidney diseases to reduce proteinuria
Used in combination therapy for resistant hypertension

Side Or Adverse Effects

Persistent dry cough due to increased bradykinin levels
Hypotension especially after initial dosing or in volume-depleted patients
Hyperkalemia resulting from decreased aldosterone secretion
Renal impairment or acute kidney injury especially in patients with bilateral renal artery stenosis
Dizziness and light-headedness due to blood pressure lowering effects
Angioedema manifesting as facial, tongue, or throat swelling, which can be life-threatening
Fatigue and weakness related to hypotension or electrolyte imbalances
Headache
Nausea and gastrointestinal discomfort
Elevations in serum creatinine and blood urea nitrogen
Rarely, liver dysfunction or hepatitis
Rash and pruritus as hypersensitivity reactions
Electrolyte disturbances such as hyponatremia

Precautions

Use cautiously in patients with impaired renal function or on dialysis
Avoid use in patients who have a history of angioedema related to previous ACE inhibitor therapy
Monitor serum potassium levels regularly to detect hyperkalemia
Use with caution in patients with bilateral renal artery stenosis due to risk of renal failure
Avoid use during pregnancy due to teratogenic effects and fetal toxicity
Monitor blood pressure to avoid excessive hypotension especially in volume-depleted patients
Caution when used concomitantly with diuretics as risk of hypotension increases
Avoid potassium supplements or potassium-containing salt substitutes unless monitored
Monitor liver function tests due to rare reports of hepatotoxicity
Adjust dosage carefully in elderly patients with comorbidities
Discontinue if signs of angioedema appear and seek immediate medical attention

Warnings

Contraindicated in pregnancy due to risk of fetal injury and death, especially in second and third trimesters
Risk of angioedema requiring emergency intervention
Potential for acute renal failure in patients with bilateral renal artery stenosis or severe renal impairment
Hyperkalemia risk especially when combined with potassium-sparing diuretics or potassium supplements
Risk of symptomatic hypotension especially in hypovolemic patients
Use with caution in combination with sacubitril-containing medications; should not be administered within 36 hours before or after sacubitril
Possibility of severe allergic reactions including anaphylaxis
Potential interaction with NSAIDs leading to reduced antihypertensive effect and worsening renal function
May worsen existing kidney disease if not carefully monitored
Not recommended during breastfeeding due to unknown excretion in milk

Contraindications

Known hypersensitivity to benazepril or any other ACE inhibitor
History of angioedema related to previous ACE inhibitor therapy
Pregnancy, especially during the second and third trimesters
Use within 36 hours before or after administration of sacubitril-containing medications (e.g., Entresto)
Concomitant use with aliskiren in patients with diabetes or renal impairment
Bilateral renal artery stenosis causing renal artery hypoperfusion
Severe hypotension or shock

Drug Interactions

Potassium-sparing diuretics (spironolactone, triamterene, amiloride) increasing risk of hyperkalemia
Nonsteroidal anti-inflammatory drugs (NSAIDs) possibly reducing antihypertensive efficacy and causing renal impairment
Aliskiren coadministration contraindicated in diabetic or renal impaired patients due to risk of renal impairment and hyperkalemia
Sacubitril (Entresto) contraindicated within 36 hours due to risk of angioedema
Insulin and other antidiabetic agents may necessitate dose adjustments as benazepril can enhance hypoglycemic effects
Immunosuppressants like sirolimus, temsirolimus, and everolimus may increase nephrotoxicity risk
Other antihypertensive drugs may have additive blood pressure-lowering effects increasing hypotension risk
Lithium clearance may be reduced leading to lithium toxicity
Gold therapy (in intramuscular form) risk of nitritoid reactions increased
Coadministration with diuretics may cause excessive hypotension, especially on therapy initiation

Preparations Of The Drug

Oral tablet: 5 mg
Oral tablet: 10 mg
Oral tablet: 20 mg
Oral tablet: 40 mg
Available as monotherapy tablets for oral administration
Can be compounded into oral suspension for pediatric dosing