Pharmacokinetics of toremifene.

The pharmacokinetics of toremifene has been investigated in man after single and multiple oral doses. Toremifene was completely absorbed without first-pass metabolism. Peak concentration in serum was achieved in 4 h. Mean half-lives of distribution and elimination were 4 h and 5 days, respectively. Kinetics was linear in the studied dose-range of 10-680 mg. Toremifene was over 99% bound to plasma proteins and extensively metabolized. The main metabolites in serum were demethyl- and deaminohydroxytoremifene. In patients receiving multiple dosing of 60 mg/day serum steady-state level of toremifene was 0.8 microgram/ml on average. The level of demethyl metabolite was twice and that of deaminohydroxy metabolite was one tenth of toremifene.