1993 Volume 8 Issue 5 Pages 1029-1040
Quinotolast sodium, a new anti-allergic drug, was studied in six healthy male volunteers to evaluate its pharmacokinetics in steady-state conditions after oral dosing. The subjects were given a single dose of 5mg, and after a two-day washout period, followed by 5mg every 12 hours in the morning and evening for six days and once in the next morning. The pharmacokinetics of quinotolast were well described by a linear model fitting to a biexponential equation with first-order absorption. The steady state was reached by the second day of multiple dosing with terminal half-life of 8.4 hours. The in vivo plasma protein binding was as high as 98.7%. Quinotolast was hardly excreted unchanged in the urine, while 22.6 and 19.0% of the dose were excreted as its glucuronide and hydroxy metabolite, respectively. The trough concentrations in the morning were significantly higher than those in the evening. The difference was mostly related to the slower absorption in the evening. The pharmacokinetic calculations suggest that quinotolast is hardly subjected to first-pass hepatic metabolism.
