Mechanism of Action
Description: Benazepril, a prodrug of benazeprilat, acts by inhibiting ACE that catalyzes the conversion of angiotensin I to angiotensin II (a potent vasoconstrictor), thus leading to reduced aldosterone (a hormone that causes water and Na retention) secretion by the adrenal cortex and decreased vasopressor activity.
Onset: W/in 1 hr.
Duration: Approx 24 hr.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract (approx 37%). Time to peak plasma concentration: 1-2 hr (fasting state); 2-4 hr (nonfasting state).
Distribution: Crosses placenta and enters breast milk (small amounts). Volume of distribution: Approx 8.7 L. Plasma protein binding: Approx 97% (benazepril); approx 95% (benazeprilat).
Metabolism: Undergoes rapid and extensive enzymatic hydrolysis to its active metabolite (benazeprilat) in the liver.
Excretion: Via urine (small amounts of benazepril; 20% as benazeprilat; 12% as other metabolites) and bile (approx 11-12%). Elimination half-life: 10-11 hr (benazeprilat).