Leukemic cell versus plasma levels of daunorubicin and daunorubicinol after infusion of daunorubicin as free drug or the DNA complex.

In two patients with acute non-lymphocytic leukemia, leukemic cell as well as plasma concentrations of Daunorubicin (D) and Daunorubicinol (DOH) were studied after administration of D as free drug or as a complex with DNA. The peak plasma concentration of D was slightly higher after infusion of the D-DNA complex than after free drug while the intracellular pattern was the opposite. The intracellulr peak concentrations were found to be 50-100 fold higher and displayed a kinetic pattern which was completely different from that of D in plasma. We therefore suggest that assays of the concentrations of the drug and its toxic metabolite in leukemic cells are more relevant than the monitoring of plasma concentrations in the evaluation of the clinical effect of this drug's action.