Tirapazamine (Tirazone)

Mechanism of action

From the NCI Drug Dictionary: A benzotriazine di-N-oxide with potential antineoplastic activity. Tirapazamine is selectively activated by multiple reductases to form free radicals in hypoxic cells, thereby inducing single-and double-strand breaks in DNA, base damage, and cell death. This agent also sensitizes hypoxic cells to ionizing radiation and inhibits the repair of radiation-induced DNA strand breaks via inhibition of topoisomerase II.