IMURAN is indicated as an adjunct for the prevention of rejection in renal homotransplantation.

It is also indicated for the management of active rheumatoid arthritis to reduce signs and symptoms.

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Rheumatoid Arthritis -- A chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures. Etiology is unknown, but autoimmune mechanisms have been implicated.

Physical findings -- Objective evidence of disease perceptible to the examining physician.

Symptoms -- An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.

IMURAN should not be given to patients who have shown hypersensitivity to the drug.

IMURAN should not be used for treating rheumatoid arthritis in pregnant women.

Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of neoplasia if treated with IMURAN.

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Hypersensitivity -- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.

Rheumatoid Arthritis -- A chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures. Etiology is unknown, but autoimmune mechanisms have been implicated.

Neoplasms -- New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.

Severe leukopenia, thrombocytopenia, macrocytic anemia, and/or pancytopenia may occur in patients being treated with IMURAN.

Severe bone marrow suppression may also occur.

Patients with intermediate thiopurine S-methyl transferase (TPMT) activity may be at an increased risk of myelotoxicity if receiving conventional doses of IMURAN.

Patients with low or absent TPMT activity are at an increased risk of developing severe, life-threatening myelotoxicity if receiving conventional doses of IMURAN.

TPMT genotyping or phenotyping can help identify patients who are at an increased risk for developing IMURAN toxicity.2-9 (See PRECAUTIONS: Laboratory Tests).

Hematologic toxicities are dose-related and may be more severe in renal transplant patients whose homograft is undergoing rejection.

It is suggested that patients on IMURAN have complete blood counts, including platelet counts, weekly during the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage alterations or other therapy changes are necessary.

Delayed hematologic suppression may occur.

Prompt reduction in dosage or temporary withdrawal of the drug may be necessary if there is a rapid fall in or persistently low leukocyte count, or other evidence of bone marrow depression.

Leukopenia does not correlate with therapeutic effect; therefore the dose should not be increased intentionally to lower the white blood cell count.Serious infections are a constant hazard for patients receiving chronic immunosuppression, especially for homograft recipients.

Fungal, viral, bacterial, and protozoal infections may be fatal and should be treated vigorously.

Reduction of azathioprine dosage and/or use of other drugs should be considered.

IMURAN is mutagenic in animals and humans, carcinogenic in animals, and may increase the patient's risk of neoplasia.

Renal transplant patients are known to have an increased risk of malignancy, predominantly skin cancer and reticulum cell or lymphomatous tumors.

The risk of post-transplant lymphomas may be increased in patients who receive aggressive treatment with immunosuppressive drugs.

The degree of immunosuppression is determined, not only by the immunosuppressive regimen, but also by a number of other patient factors.

The number of immunosuppressive agents may not necessarily increase the risk of post-transplant lymphomas.

However, transplant patients who receive multiple immunosuppressive agents may be at risk for over-immunosuppression; therefore, immunosuppressive drug therapy should be maintained at the lowest effective levels.

Information is available on the spontaneous neoplasia risk in rheumatoid arthritis, and on neoplasia following immunosuppressive therapy of other autoimmune diseases.

It has not been possible to define the precise risk of neoplasia due to IMURAN.

The data suggest the risk may be elevated in patients with rheumatoid arthritis, though lower than for renal transplant patients.

However, acute myelogenous leukemia as well as solid tumors have been reported in patients with rheumatoid arthritis who have received azathioprine.

Data on neoplasia in patients receiving IMURAN can be found under ADVERSE REACTIONS.

IMURAN has been reported to cause temporary depression in spermatogenesis and reduction in sperm viability and sperm count in mice at doses 10 times the human therapeutic dose;10 a reduced percentage of fertile matings occurred when animals received 5 mg/kg.

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