Alkylating Agents: Alkyl Sulfonates

Alkyl Sulfonates

Busulfan

Busulfan (Myleran) is a bifunctional methanesulfonic ester that forms intrastrand cross-linkages with DNA. The drug is well absorbed after oral administration and has a plasma half-life of less than 5 minutes. Metabolites and degradation products are excreted primarily in the urine.

Busulfan is used in the palliative treatment of chronic granulocytic leukemia. Daily oral therapy re-sults in decreased peripheral white blood cells and im-proved symptoms in almost all patients during the chronic phase of the disease. Excessive uric acid pro-duction from rapid tumor cell lysis should be prevented by coadministration of allopurinol.

At usual therapeutic dosages, busulfan is selectively toxic to granulocyte precursors rather than lympho-cytes. Thrombocytopenia and anemia and less com-monly, nausea, alopecia, mucositis, and sterility also may occur. Unusual side effects of busulfan include gyneco-mastia, a general increase in skin pigmentation, and in-terstitial pulmonary fibrosis.