Synonym | 3,4-Dihydro-3-methyl-4-oxoimidazo[5,1-d]-1,2,3,5-tetrazine-8-carboxamide; NSC 362856 |
Biochem/Physiol Actions | Temozolomide is an imidazotetrazine deritave and an antineoplastic agent. It is a prodrug that has little to no pharmacological activity until it is hydrolyzed in vivo to 5-(3-methyltriazen-1-yl)imidazole 4-carboxamide (MTIC). After administration, temozolomide undergoes rapid, nonenzymatic hydrolysis at physiological pH to MTIC, which is the active form of the drug. MTIC is generated through the effect of water at the highly electropositive C4 position of temozolomide, causing the ring of temozolomide to open, release carbon dioxide, and generate MTIC. Temozolomide is a triazene analog of dacarbazine with antineoplastic activity. As a cytotoxic alkylating agent, temozolomide is converted at physiologic pH to the short-lived active compound, monomethyl triazeno imidazole carboxamide (MTIC). The cytotoxicity of MTIC is due primarily to methylation of DNA at the O6 and N7 positions of guanine, resulting in inhibition of DNA replication. Unlike dacarbazine, which is metabolized to MITC only in the liver, temozolomide is metabolized to MITC at all sites. Temozolomide is administered orally and penetrates well into the central nervous system. |
