A synthetic derivative of dimethane-sulfonate with antineoplastic and cytotoxic properties. Although its mechanism of action is not fully understood, busulfan appears to act through the alkylation of DNA. Following systemic absorption of busulfan, carbonium ions are formed, resulting in DNA alkylation and DNA breaks and inhibition of DNA replication and RNA transcription. OR An anticancer drug that belongs to the family of drugs called gonadotropin-releasing hormones. In prostate cancer therapy, buserelin blocks the production of testosterone in the testicles.