Please note: Any medical or genetic information present in this entry is not intended as a diagnosis of your problem, but rather is provided as a helpful guide for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care. Information is not necessarily complete. Please see your doctor for diagnosis and treatment.

Please note: DNAtraffic database is the project under construction and information on this page is not finished yet.

Azathioprine


ACCESSION NB: DB00993 (APRD00811)


TYPE: small molecule


GROUP: approved


DESCRIPTION:
An immunosuppressive pro-drug. It is converted into 6-mercaptopurine in the body where it blocks purine metabolism and DNA synthesis.

VOLUME OF DISTRIBUTION: Not Available

CATEGORIES:
Antirheumatic Agents Antimetabolites Immunosuppressive Agents Antimetabolites, Antineoplastic

ABSORPTION: Well absorbed following oral administration.

INDICATION:
For use in rheumatoid arthritis, preventing renal transplant rejection, Crohn's disease, and colitis.

PHARMACODYNAMICS:
Azathioprine is a chemotherapy drug, now rarely used for chemotherapy but more for immunosuppression in organ transplantation and autoimmune disease such as rheumatoid arthritis or inflammatory bowel disease or Crohn's disease. It is a pro-drug, converted in the body to the active metabolite 6-mercaptopurine. Azathioprine acts to inhibit purine synthesis necessary for the proliferation of cells, especially leukocytes and lymphocytes. It is a safe and effective drug used alone in certain autoimmune diseases, or in combination with other immunosuppressants in organ transplantation. Its most severe side effect is bone marrow suppression, and it should not be given in conjunction with purine analogues such as allopurinol. The enzyme thiopurine S-methyltransferase (TPMT) deactivates 6-mercaptopurine. Genetic polymorphisms of TPMT can lead to excessive drug toxicity, thus assay of serum TPMT may be useful to prevent this complication.

MECHANISM OF ACTION:
Azathioprine antagonizes purine metabolism and may inhibit synthesis of DNA, RNA, and proteins. It may also interfere with cellular metabolism and inhibit mitosis. Its mechanism of action is likely due to incorporation of thiopurine analogues into the DNA structure, causing chain termination and cytotoxicity.

PROTEIN BINDING:
Azathioprine and the metabolite mercaptopurine are moderately bound to serum proteins (30%).

METABOLISM:
Primarily converted to the active metabolites 6-mercaptopurine and 6-thioinosinic acid via a non-enzymatica process. 6-mercaptopurine is subsequently metabolized primarily by xanthine oxidase. Enzyme Metabolite Reaction Km Vmax Thiopurine S-methyltransferase S-methylazathioprine S-methylation

TOXICITY:
The oral LD50 for single doses of azathioprine in mice and rats are 2500 mg/kg and 400 mg/kg, respectively. Very large doses of this antimetabolite may lead to marrow hypoplasia, bleeding, infection, and death.

AFECTED ORGANISMS:
Humans and other mammals