Identification of human urinary mitoxantrone metabolites

Two polar metabolites of mitoxantrone, a clinically active antitumor agent, have been isolated and purified from the urine of patients by sequential absorption on glass wool and C18-Sep-Pak cartridges followed by preparative high-performance liquid chromatography. Negative ion chemical ionization mass spectrometry indicated that the two metabolites are the di- and mono-carboxylic acids resulting from oxidation of the terminal hydroxyl groups of the side chain(s). Mass spectral comparison of the urinary metabolites with synthetic compounds confirmed the identification.