adriamycin-aglycone and 7-deoxyadriamycin-aglycone

Recombinant human granulocyte colony-stimulating factor (G-CSF) has been shown to reduce neutropenia following cytotoxic therapy, thereby enabling dose escalation to improve the response rate. It is important to know whether drug kinetics change as doses are increased. Doxorubicin was selected because of its broad spectrum of activity and its known efficacy in metastatic breast cancer. Doses of 75, 100, 125 and 150 mg/m2 were given to 11 patients with metastatic breast cancer by infusion over 30 min. Serum concentrations of parent drug and metabolites were determined during the first 48 h following the infusion by high-performance liquid chromatography (HPLC). The serum concentration vs time curve decayed as a triple exponential function in four patients and as a double exponential function in seven. A four-compartment model, one central and three peripheral, would predict concentrations to within 1 SE of the observed values. Doxorubicinol was the principal metabolite, and doxorubicinone and 7-deoxydoxorubicinone were clearly identified. There was a linear increase in the AUC infinity with dose. In addition, a small and transient increase in circulating levels of doxorubicinol and other important metabolites was observed 6 h following the administration of doxorubicin, which suggests the existence of an enterohepatic, or other, re-circulation mechanism. We conclude that in the dose range selected the kinetics of doxorubicin are linear and that the increase in toxicities seen with the higher doses of doxorubicin, following the second and third fortnightly administration, may be due to intracellular drug accumulation in tissues.

Topics: Adult; Breast Neoplasms; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Doxorubicin; Female; Half-Life; Humans; Metabolic Clearance Rate; Middle Aged; Naphthacenes

In five cancer patients we have determined the pharmacokinetics of 4'-deoxydoxorubicin (4'-DOX), its alcoholic metabolite 4'-deoxydoxorubicinol and the occurrence of circulating 7-deoxyaglycone metabolites. The 7-deoxyaglycone of the alcohol metabolite, the major aglycone of Adriamycin (ADR) present in man, was not detected in any serum sample. The 7-deoxyaglycone of the parent drug, which appears in concentrations in excess of 30 ng/ml after ADR administration, was detected in only 2/5 patients in trace amounts. These preliminary data indicate a difference in biotransformation between ADR and 4'-DOX despite their close structural similarities.

Topics: Biotransformation; Chromatography, High Pressure Liquid; Doxorubicin; Female; Half-Life; Humans; Kidney Neoplasms; Male; Naphthacenes