Adult Dosing
Renal Homotransplantation
- Starting dose: 3-5 mg/kg IV x 1, beginning at the time of transplant; may be started up to 3 days before transplant
- Maint. dosage: 1-3 mg/kg/day
- Note: Indicated only in patients who are unable to tolerate oral medications
Rheumatoid Arthritis
- Start 0.5 mg/kg/day IV q12-24 hrs
- If unsatisfactory response after 6-8 wks, increase dose by 0.5 mg/kg/day q4 wks
- Max: 2.5 mg/kg/day
- If no response after 12 wks, discontinue
Notes- Severe toxicity in renal transplantation, may require discontinuation
- Hepatic veno-occlusive disease, permanently discontinue
- Dosage adjustment for concomitant use with allopurinol: Decrease dose by 33% or 25% the usual dose concurrently with allopurinol
- Patients with lacking or very low TPMT activity may require decrease in dose or discontinuation
- Dosage adjustment for toxicity: In rapid decrease in WBC count, progressive low WBC count, or in serious infections, decrease dose or hold the treatment temporarily
Goodpastures syndrome [Non-FDA Approved]
- Initial loading dose: 3-5 mg/kg IV given x 1 dose then start maintenance dose in 24 hours
- Maintenance: 1-3 mg/kg/day IV given qd
Pediatric Dosing
- Note: Safety and effectiveness in pediatric population have not been established
Renal Homotransplantation (Not FDA Approved)
- Starting dose: 3-5 mg/kg IV x 1, beginning at the time of transplant; may be started up to 3 days before transplant
- Maint. dose: 1-3 mg/kg/day
- Note: Indicated only in patients who are unable to tolerate oral medications
Goodpastures syndrome [Non-FDA Approved]
- Initial loading dose: 3-5 mg/kg IV given x 1 dose then start maintenance dose in 24 hours
- Maintenance: 1-3 mg/kg/day IV given qd
Renal Dose Adjustment (Based on CrCl)
- 10-50 mL/min: Decrease dose by 25%
- <10 mL/min: Decrease dose by 50%
Hepatic Dose Adjustment
- Hepatic impairment: Use with caution; dose adjustments not defined
See Supplemental Patient Information
- Azathioprine is a purine antimetabolite with carcinogenic and mutagenic potential
- Risk of severe bone marrow suppression; severe leukopenia, thrombocytopenia, macrocytic anemia, and/or pancytopenia have been reported
- Monitor CBC with platelet counts qwk x 1 month, then q2 wk for second and third month, then monthly
- 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
- Reversible GI hypersensitivity reaction with severe nausea and vomiting may occur; most common during first few weeks of therapy
- Delayed hematologic suppression may occur. Reduce dosage or temporarily withdraw therapy if rapid fall in WBC or persistent leukopenia, or evidence of bone marrow depression
- Azathioprine may cause fetal harm when administered to a pregnant woman
- Serious fungal, viral, bacterial and protozoal infections may develop in patients on long-term immunosuppression
Cautions: Use cautiously in
- Severe renal impairment
- Oliguria
- Malignancies
- Reduced bone marrow reserve
- Concurrent use of other immunosuppressants
- Patients with TPMT enzyme deficiency
- Previous or concurrent radiation therapy
- Chronic debilitating illnesses
Supplemental Patient Information
- Azathioprine is a hazardous agent therefore proper precautions should be taken while handling or disposing the drug
Pregnancy Category:D
Breastfeeding: Possibly unsafe. Azathioprine and its active metabolite are excreted in breastmilk in low levels. Possible risk of immunosuppression, growth retardation, and carcinogenesis in breastfed infants; monitor exclusively breastfed infants with a complete blood count with differential, and liver function tests. This information is based upon LactMed database (available at http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT last accessed 10 July 2010). According to manufacturer's data, use during breastfeeding is not recommended.
Note: Chronic immunosuppression with this agent may increase risk of neoplasia
- HEMA: Leukopenia, thrombocytopenia, macrocytic anemia, bleeding
- GI: Nausea, vomiting, diarrhea, anorexia, abdominal pain, hepatotoxicity (increased serum alkaline phosphatase, bilirubin, and/or serum transaminases), pancreatitis, hepatic veno-occlusive disease
- DERM: Rash, alopecia
- MUSC: Myalgia, arthralgia
- RESP: Reversible interstitial pneumonitis
- LOCAL: Application-site reactions including mild local erythema
- MISC: Super infection, fever, malaise, neoplasia, immunosuppression
