[A pharmacokinetic study of idarubicin hydrochloride, a new anthracycline anti-tumor drug, in patients with acute leukemia. Idarubicin Study Group].

In 21 patients with acute leukemia, idarubicin hydrochloride, a new anthracycline antitumor drug, was administered i.v. for 3 consecutive days to study the pharmacokinetics. The terminal half-lives (t1/2) of the drug in these patients were 6.40-15.10 hrs. in plasma, and 8.09-16.34 hrs. in blood cells. Its main metabolite idarubicinol remained longer in blood; t1/2 values were 43.46-51.01 hrs. in plasma and 36.61-54.70 hrs. in blood cells. After 2-4 hrs, the concentrations of idarubicinol in both plasma and blood cells exceeded those of idarubicin. The AUCs of idarubicinol in plasma were 5.16-8.36 times higher than those of idarubicin, and AUCs of idarubicinol in blood cells were 2.05-4.57 times higher than those of idarubicin. Among the doses ranged from 5 to 15 mg/m2/day, the AUCs of both idarubicin and idarubicinol increased dose-dependently. In 2-compartment multiple dose models, plasma t1/2 alpha and t1/2 beta of idarubicin were 0.25 +/- 0.13 hrs. and 9.4 +/- 3.4 hrs., respectively. The steady-state volume of distribution (Vdss) was 934.9 +/- 370.7 l/m2, and the plasma clearance was 82.3 +/- 29.7 l/hr/m2. The urinary excretion of the drug was comparatively low. Until 7 days after administration, the mean cumulative urinary recovery rates of idarubicin and idarubicinol were 2.04% and 11.53%, respectively, and 13.57% in total.