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Important Safety Information

Adverse Reactions

Adverse Reactions – Clinical Studies Experience
The most common adverse reaction occurring in >20% of patients is myelosuppression including anemia, neutropenia, lymphopenia and thrombocytopenia. Adverse reactions occurring 5 to 20% include anorexia, nausea, vomiting, diarrhea, malaise, and rash. Adverse reactions occurring in <5 % of patients include urticaria, hyperuricemia, oral lesions, elevated transaminases, hyperbilirubinemia, hyperpigmentation, infections, and pancreatitis. Oral lesions resemble thrush rather than antifolic ulcerations. Delayed or late toxicities include hepatic fibrosis, hyperbilirubinemia, alopecia, pulmonary fibrosis, oligospermia and secondary malignancies.

Adverse Reactions – Postmarketing Experience
The following adverse reactions have been identified during post-approval use of PURIXAN. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. These reactions include: photosensitivity, hypoglycemia, portal hypertension and pancreatitis.

Warnings and Precautions

Myelosuppression
The most consistent, dose-related toxicity of PURIXAN is bone marrow suppression.

Monitor complete blood count (CBC) and adjust the dose of PURIXAN for severe neutropenia and thrombocytopenia.

Evaluate patients with repeated severe myelosuppression for thiopurine S-methyltransferase (TPMT) or nucleotide diphosphatase (NUDT15) deficiency.

Avoid the concurrent use of allopurinol and PURIXAN.

Hepatotoxicity
Mercaptopurine is hepatotoxic. There are reports of deaths attributed to hepatic necrosis associated with the administration of mercaptopurine. Hepatic injury can occur with any dosage, but seems to occur with greater frequency when the recommended dosage is exceeded.

Monitor serum transaminases, alkaline phosphatase, and bilirubin levels. Hold or adjust the dose of PURIXAN.

Immunosuppression
Mercaptopurine is immunosuppressive and may impair the immune response to infectious agents or vaccines.

Embryo-Fetal Toxicity
PURIXAN can cause fetal harm when administered to a pregnant woman.  If this drug is used during pregnancy or if the patient becomes pregnant while taking the drug, the patient should be apprised of the potential hazard to a fetus.

Treatment Related Malignancies
Cases of hepatosplenic T-cell lymphoma have been reported in patients treated with mercaptopurine for inflammatory bowel disease, for which mercaptopurine is not approved.

A treatment regimen containing multiple immunosuppreants should therefore be used with caution as this could lead to lymphoprofliferative disorders.

Macrophage Activation Syndrome
Macrophage activation syndrome (MAS) (hemophagocytic lymphohistiocytosis) is a known, life-threatening disorder that may develop in patients with autoimmune conditions, in particular with inflammatory bowel disease (IBD), and there could potentially be an increased susceptibility for developing the condition with the use of mercaptopurine (an unapproved use). If MAS occurs, or is suspected, discontinue mercaptopurine. Monitor for and promptly treat infections such as EBV and cytomegalovirus (CMV), as these are known triggers for MAS.