Spiromustine is a bifunctional nitrogen alkylating agent with antineoplastic activity and lipophilic properties. Preclinical screening has shown activity against a variety of tumors, including an intracranially implanted ependymoblastoma. Alkylating activity has been demonstrated in an intracerebral glioma in the rat. Spiromustine is a cell cycle non-specific agent. Animal pharmacology studies have shown a biphasic plasma decay curve, with hepatic metabolism and excretion, an enterohepatic circulation of metabolites, and approximately 50% renal excretion of unchanged drug. Toxicology studies in mice, rats, and dogs showed that dose-related myelosuppression and neurotoxicity predominated; other organ toxicities were mild. In Phase I clinical trials Neurotoxicity was the dose-limiting toxicity presenting as alterations in cortical integrative functions (orientation, language, coordination), leading to a decrease in the level of consciousness.