The pharmacokinetics of molsidomine were investigated in six young (25.5 +/- 0.6 years) and in six elderly healthy volunteers (81.1 +/- 3.1 years). After a 2 mg oral administration, molsidomine elimination half-life was prolonged in elderly subjects (1.9 +/- 0.2 h versus 1.2 +/- 0.1 h, P less than 0.05) because of a decrease in its plasma clearance (15.1 +/- 3.2 l.h-1 versus 41.8 +/- 2.5 l.h-1 (P less than 0.01) in young volunteers). The elimination half-life of the active metabolite, SIN-1 or linsidomine was also prolonged in elderly subjects (1.8 +/- 0.2 h versus 1.0 +/- 0.08 h, P less than 0.05). AUCs of both molsidomine and SIN-1 were increased in the elderly subjects, but the increase in the former was greater (x 3.4) than the increase in the latter (x 1.6). These results suggest that pharmacokinetics and metabolism of molsidomine are impaired in elderly subjects.