巯嘌呤 (Purixan, Xaluprine (previously Mercaptopurine Nova Laboratories))

概览

Mercaptopurine is an antineoplastic agent used to treat acute lymphocytic leukemia.

作用机制

Mercaptopurine competes with hypoxanthine and guanine for the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) and is itself converted to thioinosinic acid (TIMP). TIMP inhibits several reactions that involve inosinic acid (IMP), such as the conversion of IMP to xanthylic acid (XMP) and the conversion of IMP to adenylic acid (AMP) via adenylosuccinate (SAMP). Upon methylation, TIMP forms 6-methylthioinosinate (MTIMP) which inhibits glutamine-5-phosphoribosylpyrophosphate amidotransferase in addition to TIMP. Glutamine-5-phosphoribosylpyrophosphate amidotransferase is the first enzyme unique to the de novo pathway for purine ribonucleotide synthesis. According to experimental findings using radiolabeled mercaptopurine, mercaptopurine may be recovered from the DNA in the form of deoxythioguanosine. In comparison, some mercaptopurine may be converted to nucleotide derivatives of 6-thioguanine (6-TG) via actions of inosinate (IMP) dehydrogenase and xanthylate (XMP) aminase that convert TIMP to thioguanylic acid (TGMP).

适应症

For remission induction and maintenance therapy of acute lymphatic leukemia.

• Acute Lymphoblastic Leukaemias (ALL)
• Acute Promyelocytic Leukemia
• Autoimmune Hepatitis
• Crohn's Disease (CD)
• Lymphoblastic Lymphoma
• Ulcerative Colitis