Pharmacokinetics of Quinotolast Sodium in the Elderly.

Abstract

The pharmacokinetics of quinotolast sodium, a new anti-allergic drug, were studied in six elderly and six young healthy male volunteers after single oral dosing with 5mg of the drug. The mean maximum plasma concentration of unchanged drug increased significantly from 171ng/ml in the young to 284ng/ml in the elderly volunteers. However, the time to reach the maximum plasma concentration, area under the plasma concentration-time curve, elimination half-life and apparent oral clearance did not differ between the two groups and were as follows : 1.7 and 1.5hours ; 1399 and 1293ng·hr/ml ; 9.2 and 8.1 hours ; 57.0 and 61.5ml/min in the elderly and young, respectively. Quinotolast was hardly excreted unchanged in the urine, while 16.7 and 20.3% of the given dose were excreted in the urine as its glucuronide and hydroxy metabolite, respectively, in the elderly, and 20.6 and 26.5%, respectively, in the young. The urinary excretion of glucuronide in the elderly did not differ from that in the young, but hydroxy metabolite was significantly reduced in the elderly. The results of this study suggest that although possible reduction in the metabolism of hydroxylation or reduction in absorption might occur in the elderly, such a reduction was slight and would not affect the overall plasma concentration of unchanged drug.