Usage
- Benazepril is primarily prescribed for treating hypertension (high blood pressure). It’s also used to treat heart failure and improve survival rates after a heart attack. In some cases, it can be used to treat diabetic nephropathy (kidney damage caused by diabetes).
- Pharmacological Classification: Angiotensin-Converting Enzyme (ACE) inhibitor.
- Mechanism of Action: Benazepril inhibits the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. This leads to vasodilation (widening of blood vessels), reduced blood volume, and decreased aldosterone secretion, ultimately lowering blood pressure.
Alternate Names
- International Nonproprietary Name (INN): Benazepril.
- Brand Names: Lotensin. It’s also available as a generic medication and in combination with other antihypertensive medications (e.g., hydrochlorothiazide in Lotrel).
How It Works
- Pharmacodynamics: Benazepril’s primary effect is reducing blood pressure by vasodilation. It also decreases afterload (the resistance the heart works against) and preload (the amount of blood returning to the heart).
- Pharmacokinetics: Benazepril is an oral prodrug. Once absorbed, it’s metabolized by the liver into benazeprilat, the active form. Benazeprilat’s peak concentration occurs within 2 to 4 hours. Benazepril and benazeprilat are primarily excreted by the kidneys.
- Mode of Action: Benazepril, through its active metabolite benazeprilat, blocks the angiotensin-converting enzyme (ACE). ACE converts angiotensin I to angiotensin II, and angiotensin II is a potent vasoconstrictor. By inhibiting ACE, benazepril reduces angiotensin II levels. This leads to vasodilation, reduced vascular resistance, and decreased blood pressure. Additionally, it reduces aldosterone secretion from the adrenal glands, leading to a decrease in sodium and water retention. This effect contributes further to blood pressure reduction. Benazepril does not have any significant effects on heart rate.
- Receptor Binding, Enzyme Inhibition, or Neurotransmitter Modulation: Benazepril’s primary mechanism is the inhibition of ACE, an enzyme. It doesn’t bind directly to receptors or affect neurotransmitter levels.
- Elimination Pathways: Primarily renal excretion; about 30% of the administered dose is excreted unchanged in the urine. Small amounts of benazepril and benazeprilat are also found in breastmilk. The liver also plays a role in the metabolism of benazepril.
Dosage
Standard Dosage
Adults:
- Initial dose: 10 mg orally once a day (5 mg for patients on diuretics).
- Maintenance dose: 20-40 mg/day, given as a single dose or in two divided doses.
- Maximum dose: 80 mg/day.
Children (6 years and older):
- Initial dose: 0.2 mg/kg/day (up to 10 mg) once daily.
- Maintenance dose: Titrate up to 0.6 mg/kg/day as needed (maximum 40 mg/day).
- Use in children younger than 6 is not recommended.
Special Cases:
- Elderly Patients: Start with 5-10 mg/day, adjusting based on renal function.
- Patients with Renal Impairment (GFR < 30 mL/min): Initial dose is 5 mg/day. Titrate cautiously up to a maximum of 40 mg/day.
- Patients with Hepatic Dysfunction: Dose adjustments may be necessary but specific guidelines are not clearly established. Close monitoring is recommended.
- Patients with Comorbid Conditions: Use with caution in patients with heart failure, ischemic heart disease, or severe aortic stenosis. Monitor for hypotension, hyperkalemia, and changes in renal function in patients with diabetes.
Clinical Use Cases
- Intubation, Surgical Procedures, Mechanical Ventilation, ICU Use, Emergency Situations: Dosage adjustments should be patient-specific and guided by hemodynamic monitoring. Start with a lower dose and titrate as needed to achieve the desired blood pressure control.
Dosage Adjustments:
Dose modifications are necessary for patients with renal or hepatic impairment. Monitor renal function and potassium levels regularly.
Side Effects
Common Side Effects:
- Headache, dizziness, cough, fatigue, nausea, hypotension (low blood pressure).
Rare but Serious Side Effects:
- Angioedema (swelling of face, lips, tongue, throat, or extremities), kidney failure, hyperkalemia (high potassium), neutropenia (low white blood cell count).
Long-Term Effects:
Chronic kidney disease may occur with long-term use.
Adverse Drug Reactions (ADR):
Angioedema, acute renal failure, hyperkalemia, hypotension.
Contraindications
- Hypersensitivity to benazepril or any ACE inhibitor.
- History of angioedema related to ACE inhibitor use.
- Pregnancy (especially second and third trimesters).
- Concomitant use with sacubitril/valsartan or aliskiren (especially in patients with diabetes or renal impairment).
Drug Interactions
- Diuretics: Increased risk of hypotension.
- Potassium Supplements, Potassium-Sparing Diuretics: Increased risk of hyperkalemia.
- NSAIDs: Reduced antihypertensive effect and increased risk of kidney damage.
- Lithium: Increased lithium levels.
- Gold Compounds: Nitritoid reactions (flushing, nausea, vomiting, hypotension).
- Alcohol: Increased risk of hypotension.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: D (positive evidence of human fetal risk). Benazepril is contraindicated during pregnancy due to the risk of fetal harm, including renal failure and death.
- Breastfeeding: Benazepril is excreted in breast milk in small amounts. While minimal adverse effects on the infant are expected, caution is advised. Consider the risks and benefits.
Drug Profile Summary
- Mechanism of Action: ACE inhibitor; blocks the conversion of angiotensin I to angiotensin II.
- Side Effects: Headache, dizziness, cough, fatigue, nausea, hypotension, angioedema, renal impairment, hyperkalemia.
- Contraindications: Hypersensitivity, angioedema history, pregnancy, concomitant use with sacubitril/valsartan or aliskiren (in patients with diabetes or renal impairment).
- Drug Interactions: Diuretics, potassium supplements, NSAIDs, lithium, gold compounds.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy; caution during breastfeeding.
- Dosage: Adults: 10-40 mg/day; Children: 0.2-0.6 mg/kg/day; adjustments needed for renal impairment.
- Monitoring Parameters: Blood pressure, renal function, potassium levels.
Popular Combinations
- Benazepril + Hydrochlorothiazide (Lotrel): Combines the ACE-inhibiting effects of benazepril with the diuretic action of hydrochlorothiazide for enhanced blood pressure control.
Precautions
- General Precautions: Monitor renal function, potassium levels, and blood pressure regularly. Assess for signs of angioedema.
- Specific Populations (Pregnant Women, Breastfeeding Mothers, Children & Elderly): See sections on dosage and pregnancy/breastfeeding.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Benazepril?
A: Adults: Initial dose 10 mg/day (5 mg/day with diuretics), maintenance dose 20-40 mg/day. Children (6 years and older): Initial 0.2 mg/kg/day, max 40 mg/day. Renal impairment: Initial 5 mg/day, max 40 mg/day.
Q2: What are the common side effects of Benazepril?
A: Cough, headache, dizziness, fatigue, and hypotension.
Q3: How does Benazepril work?
A: It inhibits ACE, preventing the formation of angiotensin II and promoting vasodilation.
Q4: Is Benazepril safe during pregnancy?
A: No, it is contraindicated during pregnancy due to risk of fetal harm.
Q5: What are the serious side effects of Benazepril?
A: Angioedema, kidney failure, and hyperkalemia.
Q6: What drugs interact with Benazepril?
A: Diuretics, potassium supplements, NSAIDs, lithium, gold compounds.
Q7: Can Benazepril be used in children?
A: Yes, for children 6 years and older, with careful dosage adjustments based on weight.
Q8: What should I monitor in patients taking Benazepril?
A: Blood pressure, renal function, and potassium levels.
Q9: What is the role of the liver in processing benazepril?
A: The liver metabolizes benazepril to its active form, benazeprilat.
