Clinical and clinical pharmacologic studies of mitoxantrone

The drug mitoxantrone was given to 31 patients in a phase I clinical trial. The schedule of administration was once weekly for 3 weeks followed by 3 weeks of observation before further treatment. Dose range was from 1.5 to 6 mg/m2. Leukopenia was the dose-limiting toxic effect and thrombocytopenia was mild. Partial alopecia occurred in four of 12 patients evaluable for hair loss. Pharmacokinetic studies employing a fluorometric assay based on DNA binding measured by displacement of ethidium bromide revealed a first-phase half-life of about 15 minutes, with a prolonged subsequent phase. A dose of 6 mg/m2/week x 3 was well-tolerated in patients not heavily pretreated with myelosuppression therapy. Only minor clinical activity was seen with mitoxantrone.