Hepatotoxicity of mitoxantrone and doxorubicin

Doxorubicin and mitoxantrone were given to mice in a single dose of 15 mg/kg body wt (i.p.) and lipid peroxidation assays were carried out 3, 4 and 5 days after injection. Four days after injection, mitoxantrone induced an increase of 155% in liver spontaneous chemiluminescence and increases of 73% and 52% in malonaldehyde levels and hydroperoxide-initiated chemiluminescence of liver homogenates. Three days after injection, administration of doxorubicin produced increases of 51% and 53% in liver spontaneous chemiluminescence and malonaldehyde formation respectively, but no changes in hydroperoxide-initiated chemiluminescence of liver homogenates were observed. The hepatic levels of antioxidant enzymes were measured in mice treated with doxorubicin or mitoxantrone. Administration of mitoxantrone caused decreases of 50%, 27% and 42% in Cu-Zn superoxide dismutase, catalase and glutathione peroxidase activities, respectively. Doxorubicin also induced decreases in antioxidant enzyme levels but the effect was less marked. Our studies suggest that mitoxantrone might be more hepatotoxic than doxorubicin and that the mechanism of its toxicity would involve a reduction in antioxidant defenses.