Pharmacokinetics of Finasteride in the Elderly Volunteers

The pharmacokinetics of finasteride was assessed in 12 elderly and 12 young/ middle-aged volunteers following single oral administration of 5-mg drug. A plasma concentration profile of finasteride in the elderly is similar to that in young/middle-aged volunteers. Although Cmax (39.7 ng/ml) and AUC0-∞ (267 ng·hr/ml) in elderly volunteers were slightly lower than those (44.7 ng/ml and 318 ng·hr/ml) in young/middle-aged volunteers, there were no significant differences in these parameters between two groups. Also, there were no significant age-related differences in other pharmacokinetic parameters such as Tmax MRT and t1/2. Urinary concentrations of metabolites, ω-hydroxylated finasteride (M-1) and finasteride ω-oic acid (M-3), were also determined. Metabolite M-1 was not detected in any urine samples. Approximately 26.8% of the dose was excreted in urine as M-3 in the elderly, and 23.1% of the dose in young/middle-aged volunteers. These results suggest that the metabolism and disposition of finasteride are similar in the elderly and young/middle-aged volunteers after single oral administration.