Azathioprine

Azathioprine

Error creating thumbnail: File missing
Clinical data
Pregnancy category	D
Routes of administration	oral
ATC code	L04AX01 (WHO)
Legal status
Legal status	Approved Drug
Pharmacokinetic data
Bioavailability	Well absorbed
Elimination half-life	3hr
Excretion	renal, minimally
Identifiers
IUPAC name 6-(3-methyl-5-nitro-imidazol-4-yl)sulfanyl-7H-purine
CAS Number	446-86-6
PubChem CID	2265
DrugBank	APRD00811
E number	{{#property:P628}}
ECHA InfoCard	{{#property:P2566}}
Chemical and physical data
Formula	C9H7N7O2S
Molar mass	277.264 g/mol

WikiDoc Resources for Azathioprine
Articles
Most recent articles on Azathioprine Most cited articles on Azathioprine Review articles on Azathioprine Articles on Azathioprine in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Azathioprine Images of Azathioprine Photos of Azathioprine Podcasts & MP3s on Azathioprine Videos on Azathioprine
Evidence Based Medicine
Cochrane Collaboration on Azathioprine Bandolier on Azathioprine TRIP on Azathioprine
Clinical Trials
Ongoing Trials on Azathioprine at Clinical Trials.gov Trial results on Azathioprine Clinical Trials on Azathioprine at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Azathioprine NICE Guidance on Azathioprine NHS PRODIGY Guidance FDA on Azathioprine CDC on Azathioprine
Books
Books on Azathioprine
News
Azathioprine in the news Be alerted to news on Azathioprine News trends on Azathioprine
Commentary
Blogs on Azathioprine
Definitions
Definitions of Azathioprine
Patient Resources / Community
Patient resources on Azathioprine Discussion groups on Azathioprine Patient Handouts on Azathioprine Directions to Hospitals Treating Azathioprine Risk calculators and risk factors for Azathioprine
Healthcare Provider Resources
Symptoms of Azathioprine Causes & Risk Factors for Azathioprine Diagnostic studies for Azathioprine Treatment of Azathioprine
Continuing Medical Education (CME)
CME Programs on Azathioprine
International
Azathioprine en Espanol Azathioprine en Francais
Business
Azathioprine in the Marketplace Patents on Azathioprine
Experimental / Informatics
List of terms related to Azathioprine

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Azathioprine is an immunosupressant used in organ transplantation, autoimmune disease such as rheumatoid arthritis or inflammatory bowel disease such as Crohn's disease and ulcerative colitis. It is a pro-drug, converted in the body to the active metabolites 6-mercaptopurine and 6-thioinosinic acid.

Azathioprine is produced by a number of generic manufacturers and as branded names (Azasan by Salix in the U.S., Imuran by GlaxoSmithKline in Canada and the U.S., Australia and UK and Azamun in Finland).

History

Azathioprine was first introduced into clinical practice by Sir Roy Calne, the British pioneer in transplantation. Following the work done by Sir Peter Medawar in discovering the immunological basis of rejection of transplanted tissues and organs, Calne introduced 6-mercaptopurine as an experimental immunosuppressant for kidney transplants. When azathioprine was discovered, he then introduced it as a less toxic replacement for 6-mercaptopurine. For many years, dual therapy with azathioprine and steroids was the standard anti-rejection regime, until cyclosporine was introduced into clinical practice (also by Calne) in 1978.

Mechanism of action

Azathioprine acts to inhibit purine synthesis necessary for the proliferation of cells, especially leukocytes and lymphocytes. It is an effective drug used alone in certain autoimmune diseases, or in combination with other immunosuppressants in organ transplantation. Side effects are uncommon, but include nausea, HA and rash. Because azathioprine suppresses the bone marrow, patients will be more susceptable to infection. Caution should be exercised when it is used 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.

Mycophenolate mofetil is increasingly being used in place of azathioprine in organ transplantation as it is associated with less bone marrow suppression, fewer opportunistic infections and a lower incidence of acute rejection. However azathioprine certainly still has a major role.

Long term side effects

Metabolic pathway for azathioprine

It is listed as a human carcinogen in the 11th Report on Carcinogens of the U.S. Department of Health and Human Services, although they note that the International Agency for Research on Cancer (IARC) considered some of the animal studies to be inconclusive because of limitations in the study design and inadequate reporting. The risks involved seem to be related both to the duration and dosage used. People who have previously been treated with an alkylating agent may have an excessive risk of cancers if treated with azathioprine. Epidemiological studies have provided "sufficient" evidence of Azathioprine carcinogenicity in humans, although the methodology of past studies and the possible underlying mechanisms are questioned. The various diseases requiring transplantation, and thus azathioprine, may in themselves increase the risks of non-Hodgkin's lymphoma, squamous cell carcinomas of the skin, hepatobiliary carcinomas and mesenchymal tumours to which azathioprine may add additional risks. Those receiving azathioprine for rheumatoid arthritis may have a lesser risk than those following transplantation.

Azathioprine is not thought to cause fetal malformation (teratogenesis) and any risk to the offspring of treated men is small. A more recent product monograph produced by Glaxo Smith Kline and dated June 2005 does note that IMURAN® can cause fetal harm when given to a pregnant woman. Their document also states that the drug should not be given during pregnancy or in patients of reproductive potential without careful weighing of benefit versus the risks and should be avoided whenever possible in pregnant women. It goes on to say that when used in pregnancy the patient should be apprised of the potential hazard to the fetus. While stating that no adequate and well-controlled studies have taken place in humans, it notes that when given to animals in doses equivalent to human dosages teratogenesis was observed. Transplant patients already on this drug should not discontinue on becoming pregnant. This contrasts to the later developed drugs tacrolimus and myophenolate which are contra-indicated by the manufacturers during pregnancy. As for all cytotoxic drugs, it is advised not to breastfeed whilst taking azathioprine.

Under FDA rules, this drug, like many others, excludes eligibility for blood donation.

External links

• Imuran® (GlaxoSmithKline Patient Information Leaflet)
• Azasan® (manufacturer's website)
• Medline Plus advice on Imuran ( A service of the National Institutes of Health)
• GSK Product Monograph for Imuran (for Canadian patients only)

Template:WikiDoc Sources