Single dose pharmacokinetics of cetirizine in young and elderly volunteers

The pharmacokinetics of the H1-receptor antagonist cetirizine were studied from 0 to 48 h after a single oral intake of 10 mg in 10 elderly volunteers (60 to 90 years) and in 10 young healthy volunteers (21 to 29 years). In young healthy volunteers about 60% of an oral dose of cetirizine was excreted in the urine in unchanged form. Mean plasma concentrations were slightly higher in the elderly subjects. Cmax (362 ng/ml), Tmax (1.30 h), terminal half-life (11.8 h) and AUC infinity (4316 ng.h/ml) in the elderly subjects were somewhat higher than in the young subjects (Cmax: 337 ng/ml, Tmax: 1.12 h, terminal half-life: 10.6 h, AUC: 3721 ng.h/ml), but the difference was not significant. The mean cumulative urinary excretion at 32 h was significantly lower in the elderly subjects. It is concluded that the slight differences in pharmacokinetics of cetirizine between young and elderly subjects after single oral intake can be attributed to the decreased renal clearance in the elderly.