[Pharmacokinetics and action mechanism of anthracyclines]

For the purpose of establishing a method for reasonable clinical use of anthracyclines in leukemia chemotherapy, we examined the pharmacokinetics and the mode of action with five anthracyclines such as daunorubicin (DNR), doxorubicin (DOX), aclarubicin (ACR), THP adriamycin (THP), idarubicin (IDA). In the patients with AML, blood ACR or IDA level increased and then disappeared very rapidly after iv bolus injection. In contrast, their metabolites (M1 or IDAol) increased for up to 2 or 4 hrs and remained much longer than ACR or IDA. The concentration of ACR, IDA or their metabolites were found to be much higher in the leukocyte fraction than in erythrocyte fraction or plasma. In HL60 cell suspension, anthracyclines were rapidly accumulated into the cells, and the uptake of IDA or THP were higher than the other agents. In HL60 cells, anthracyclines accumulated in the nuclear fraction but ACR was accumulated markedly in the cytosol fraction. From the result of DNA binding assay, binding at excess to calf thymus DNA of ACR was suggested to be approximately 2 times higher than that of other agents. DNA strand brakes in HL60 cells treated with anthracyclines were shown by pulse field gel electrophoresis, and IDA was found to have stronger activity to cause the DNA strand breaks. In conclusion, it seemed that anthracyclines showed similar action mechanisms, but in some respects quantitative differences were existed among them. Anthracyclines should be given to patients based on their pharmacological characteristics to obtain higher remission rate and suppress resistant cells.