Sensitive and specific determination of the new anthracycline analog 4'-epidoxorubicin and its metabolites by high pressure liquid chromatography.

A sensitive and specific method for the determination of 4'-epidoxorubicin and its metabolites in biological fluids has been developed which uses reverse phase high pressure liquid chromatography and fluorescence detection. Danuorubicin was used as an internal standard. The limit of detection for 4'-epidoxorubicin and 4'-epidoxorubicinol was 1 ng/injection, and concentrations as low as 5 ng/ml could be analyzed in plasma and urine. Preliminary pharmacokinetic studies were performed on three patients receiving a 15-min infusion of 4'-epidoxorubicin, one at a dose of 50 mg/m2 and two at 60 mg/m2. A beta-glucuronide of 4'-epidoxorubicin has been identified as a major metabolite in urine. Significant aglycone formation was found in plasma.