What is the onset of action of benazepril (Angiotensin-Converting Enzyme inhibitor)?

Onset of Action of Benazepril

The onset of action of benazepril occurs within 0.5-1 hours after oral administration, with peak plasma concentrations of its active metabolite benazeprilat reached within 1-2 hours. 1

Pharmacokinetic Profile

Benazepril is an angiotensin-converting enzyme (ACE) inhibitor with the following pharmacokinetic characteristics:

• Initial absorption: Peak plasma concentrations of benazepril are reached within 0.5-1.0 hours after oral administration 1
• Active metabolite formation: Benazepril is rapidly metabolized to its active form, benazeprilat, primarily in the liver 1
• Peak effect timing: Peak plasma concentrations of benazeprilat are reached within 1-2 hours 1
• Food effect: While food doesn't affect the bioavailability of benazepril, it can delay the time to peak plasma concentrations of benazeprilat to 2-4 hours 1

Clinical Onset of Effect

The antihypertensive effect of benazepril has been observed:

• As early as 30 minutes after a single dose in hypertensive patients 2
• With sustained effects during consecutive dosing for 24 hours 2
• With ACE inhibition occurring rapidly, with 80-90% inhibition of plasma ACE activity for at least 24 hours after dosing of 10 mg or more 1

Factors Affecting Onset

Several factors can influence the onset of action:

• Renal function: In patients with impaired renal function, there may be increased accumulation of benazeprilat, potentially affecting the pharmacodynamic profile 1, 2
• Concurrent medications: Benazepril has been used concomitantly with beta-blockers, calcium channel blockers, diuretics, digoxin, and hydralazine without evidence of clinically important adverse interactions 1

Clinical Implications

Understanding the rapid onset of benazepril is important for clinical practice:

• The quick onset makes it suitable for treating hypertension where prompt blood pressure control is desired
• The sustained 24-hour effect allows for once-daily dosing, as steady-state concentrations of benazeprilat are reached after 2-3 doses 1
• The effective half-life of benazeprilat following once-daily administration is 10-11 hours 1

Comparison to Other Medications

While the evidence provided doesn't directly compare benazepril's onset to other ACE inhibitors, the pharmacokinetic profile suggests a relatively rapid onset compared to some other antihypertensive medications.

Potential Adverse Effects

Despite the rapid onset, clinicians should be aware of potential adverse effects:

• ACE inhibitor-induced cough, which can occur within hours of the first dose or be delayed for weeks to months 3
• The onset of hypotensive effects should be monitored, particularly in patients who are volume-depleted or on diuretics

Understanding benazepril's onset of action helps clinicians optimize treatment strategies for hypertension and other conditions where ACE inhibitors are indicated.