Pharmacokinetics and pharmacodynamics of the ace inhibitor benazepril hydrochloride in the elderly

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Abstract
The pharmacokinetics and pharmacodynamics of a single oral dose benazepril·HCl 10 mg have been studied in 15 healthy volunteers aged 65 to 80 y. The kinetics of unchanged benazepril and its active metabolite benazeprilat did not differ significantly in males and females, so the combined kinetic data from all 15 elderly subjects were compared with a historical control group of 19–32 year-old healthy men treated in the same way. The disposition of benazepril was not affected by age. The time to maximum plasma concentration, tmax (0.5 h) and elimination half-life (0.6 h) in the elderly were the same as in young subjects. The kinetics of benazeprilat was slightly changed in the elderly; although its tmax (1.5 h) was not affected, Cmax and the AUC were 20–40% greater. The elimination half-life of benazeprilat during the first 24 h after doing in the elderly was increased by about 20% to 3.2 h. The renal plasma clearance of benazeprilat (18.1 ml·min−1) was about 20% smaller than in the young subjects. An average of 18.5% of the dose was recovered as benazeprilat in the 24 h urine from the elderly subjects, which was similar to the recovery in the young subjects. Both benazepril and benazeprilat were highly bound to serum proteins (96 and 95%, respectively). Mean systolic and diastolic blood pressures in the elderly were reduced by a maximum of 37/16 mm Hg at 6 h, in association with a small rise in pulse rate. Treatment was generally well tolerated. Three of the 15 subjects reported clinical adverse experiences judged to be possibly drug related, namely headache, abdominal pain and cold extremities.