Pharmacokinetics and tissue distribution of idarubicin and its active metabolite idarubicinol in the rabbit.

A three-compartment model was fitted to idarubicin data in a NONMEM pooled-data approach. Clearance (CL) of 221.7 ml/min was relatively high, and drug distribution was rapid (CLD = 248.3 ml/min) and extensive [steady-state volume of distribution (Vss) 24 1]. The area under the concentration-time curve (AUC) of idarbicinol was 8 times that of idarubicin. Concentrations of idarubicin (idarubicinol) measured in the myocardium at 24 h after i.v. administration of idarubicin were 20 (5) times those determined in plasma. Tissue concentrations of idarubicinol were up to 400 times those of idarubicin, indicating that the active metabolite contributes significantly to the overall drug action.