Cellular pharmacokinetics of daunorubicin: Uptake by leukaemic cells in vivo and fate

In 6 patients with acute myeloblastic leukaemia, daunorubicin was assayed in leukaemic cells from peripheral blood or bone marrow. The cells were separated from red blood cells and granulocytes by centrifugation on a Ficoll-Isopac gradient. The assay was performed by high performance liquid chromatography. Daunorubicin concentrations in peripheral leukaemic cells, 2 hours after the end of the infusion, were much higher than in plasma, the cell/plasma concentration ratio reaching about 350 and rising to almost 700 at 24 h. At that time, drug concentrations were even higher in the bone marrow leukaemic cells. The value of the assay of daunorubicin in cells as method for monitoring therapy is discussed.