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Drugs reference index «Azathioprine»


Pronunciation: (AZE-uh-THIGH-oh-preen)Class: Immunosuppressive

Trade Names:Azasan- Tablets 75 mg- Tablets 100 mg

Trade Names:Azathioprine- Injection 100 mg (as sodium)/vial

Trade Names:Imuran- Tablets 50 mg

Apo-Azathioprine (Canada)Gen-Azathioprine (Canada)


Suppresses cell-mediated hypersensitivities; alters antibody production and may reduce inflammation.



Well absorbed after oral administration.


Azathioprine and mercaptopurine are approximately 30% bound to serum proteins.


Extensively metabolized. Azathioprine is cleaved to mercaptopurine (active). Both compounds are oxidized or methylated in erythrocytes or liver. Converted to inactive 6-thiouric acid by xanthine oxidase.


Azathioprine and mercaptopurine are rapidly eliminated from blood. No azathioprine or mercaptopurine is detectable in urine after 8 h. Partially dialyzable.

Indications and Usage

Adjunct for prevention of rejection in renal homotransplantation; treatment in adults for severe, active, erosive rheumatoid arthritis not responsive to conventional management.

Unlabeled Uses

Treatment of chronic ulcerative colitis, Crohn disease, myasthenia gravis and Behcet syndrome.


Pregnancy in patients with rheumatoid arthritis.

Dosage and Administration

Renal TransplantationAdults and children

IV / PO Initiate with 3 to 5 mg/kg/day as single daily dose. Maintenance levels are 1 to 3 mg/kg/day.

Rheumatoid ArthritisAdults

PO Initial dose is 1 mg/kg given as single dose or twice daily. Dose is increased by 0.5 mg/kg/day at 6 to 8 wk, then every 4 wk if there are no serious toxicities and if initial response is unsatisfactory. Max dose is 2.5 mg/kg/day. IV Reserved for patients unable to tolerate oral medications.


Store in a tightly closed container in a cool location.

Drug Interactions


Decreases metabolism of azathioprine. Dose of azathioprine is reduced to approximately one-third to one-fourth usual dose when used concomitantly.

Nondepolarizing muscle relaxants (eg, tubocurarine, pancuronium)

Azathioprine may resist or reverse neuromuscular blockade.

Laboratory Test Interactions

None well documented.

Adverse Reactions




Nausea; vomiting.


Leukopenia; thrombocytopenia; macrocytic anemia; bleeding; selective erythrocyte aplasia.


Serious infections; neoplasias.



Chronic immunosuppression with this agent may increase risk of neoplasia.

Experienced physician should be very familiar with mutagenic potential and hematological profile.


Category D .


Excreted in breast milk.


Safety and efficacy not established.


Chronic immunosuppression with azathioprine increases risk of neoplasia. Patients with rheumatoid arthritis previously treated with alkylating agents (eg, cyclophosphamide, chlorambucil, melphalan) may have prohibitive risk of neoplasia.


Chronic immunosuppression with azathioprine increases risk of neoplasia. Patients with rheumatoid arthritis previously treated with alkylating agents (eg, cyclophosphamide, chlorambucil, melphalan) may have prohibitive risk of neoplasia.


Serious fungal, viral, bacterial and protozoal infections may develop in patients on long-term immunosuppression.

GI toxicity

Hypersensitivity reaction with severe nausea and vomiting may occur. Frequency of gastric disturbances can be reduced by giving in divided doses or after meals.

Hematologic effects

Severe hematologic toxicities (leukopenia and/or thrombocytopenia) may occur; monitor complete blood counts weekly during the first month, twice monthly for the second and third months, then monthly. Perform more frequently if dosage alterations or other therapy changes are necessary.


Occurs primarily in allograft recipients. Rare but life-threatening hepatic veno-occlusive disease has occurred in transplant patients; monitor LFTs.



Bone marrow hypoplasia, bleeding, infection, death.

Patient Information

  • Instruct patient that if once-daily dose is forgotten to skip the dose, but if 2 daily doses are missed to call the health care provider. Next dose may be doubled.
  • Explain importance of precautions regarding contact with individuals who have active infections and individuals who have recently received oral polio vaccine.
  • Identify signs of transplant rejection (eg, localized redness, tenderness and swelling in the area of the transplant, decreased transplant organ function), and remind patient that this or similar medication will be required indefinitely to prevent transplant rejection.
  • Explain that frequent follow-up appointments with a health care provider are important to adjust medication dosage.
  • Instruct patient to report the following symptoms to health care provider: unusual bleeding, decreased urine output, abdominal pain.

Copyright © 2009 Wolters Kluwer Health.

  • Azathioprine Prescribing Information (FDA)
  • Azathioprine MedFacts Consumer Leaflet (Wolters Kluwer)
  • azathioprine Concise Consumer Information (Cerner Multum)
  • azathioprine Oral, Intravenous Advanced Consumer (Micromedex) - Includes Dosage Information
  • Imuran Prescribing Information (FDA)

See Also...

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