Evaluation of the in vitro cytotoxicity of mitoxantrone following repeated freeze-thaw cycles.

Mitoxantrone, an antineoplastic anthracycline antibiotic with a wide range of veterinary applications, was developed as a less cardiotoxic alternative to doxorubicin, a related compound in this family of chemotherapy agents. Mitoxantrone has not gained widespread acceptance in the veterinary community, primarily due to its cost and single-dose packaging in a volume that exceeds the needs of the majority of veterinary cancer patients. The in vitro cytotoxicity of mitoxantrone following repeated freeze-thaw cycles was evaluated to determine whether long-term storage at -20 degrees C resulted in decreased efficacy. The drug was frozen between treatment cycles to minimize the risk of bacterial contamination because it is supplied as a preservative-free solution. Results indicated mitoxantrone maintained its cytotoxicity against cancer cells in culture following multiple freeze-thaw cycles spanning at least 12 months.