Influence of tumor on adriamycin concentration in blood cells

The relative distribution of adriamycin to plasma and blood cells after IV injection of 10 mg/kg was investigated in CD rats bearing intramuscular 256 Walker carcinosarcomas 15 days old. The drug was measured by a fluorimetric procedure and the amount of unchanged compound was separated from metabolites and quantitated by means of a TLC scanning fluorescence technique. In the presence of a tumor much lower hematocrit values are found, with marked anemia and thrombocytopenia associated with leukocytosis. These modified hematologic parameters account for an altered pattern of drug distribution. The low number of blood cells per milliliter results in a smaller amount of drug being present in the cellular fraction, so that more of the compound (even twice as much) is made available in plasma. Changes in adriamycin concentrations per unit volume or cell of each cell type are inversely related to changes in their relative number per milliliter. The only cell fraction where the drug increase per cell or cubic micrometer does not compensate the marked reduction in cell count observed in the presence of tumor is the platelet fraction, in which adriamycin amounts are 25% or less of those observed in the blood of normal rats, indicating that these blood cells become saturated in tumor-bearing animals.