Pharmacokinetics of idarubicin after daily intravenous administration in leukemic patients

We have studied the plasma pharmacokinetics of idarubicin (4-demethoxy-daunorubicin) in eight leukemia patients receiving five daily i.v. injections (7-9 mg/m2 per day) of this new anthracycline. For unchanged idarubicin, similar pharmacokinetic parameters were exhibited after the 1st and the 5th injection. Idarubicinol (13-dihydroidarubicin) was identified as the only detectable metabolite of idarubicin in plasma. Due to a protracted half-life (40 h) this compound progressively accumulated in plasma without the occurrence of peaks after the injections. This administration schedule provides therefore an interesting method of dose fractionation of a new anthracycline.