Mercaptopurine

DEA Class; Rx

Common Brand Names; Purinethol, Purixan, 6Mercaptopurine, 6MP

Thiopurine antimetabolite
Indicated for ALL as part of a combination chemotherapy regimen; common off-label use in gastroenterology for Crohn’s disease and ulcerative colitis
Patients with TPMT or NUDT15 deficiency may be at a higher risk for developing toxicity, especially severe myelosuppression

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• Elevated LFT’s (15%)
• Nausea (10%)
• Vomiting (10%)
• Stomatitis (3-10%)
• Thrombocytopenia (3-10%)
• Rash (1-3%)
• Diarrhea (1-3%)
• Dizziness (1-3%)
• Alopecia (1-3%)
• Leukopenia (1-3%)

Renal impairment

Recommended that evaluation of hemoglobin or hematocrit, total white blood cell count and differential count, and quantitative platelet count be obtained weekly while patient is on therapy

Macrophage activation syndrome (MAS) (hemophagocytic lymphohistiocytosis) a life-threatening disorder, may develop in patients with autoimmune conditions, in particular with inflammatory bowel disease (IBD); 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 therapy; monitor for and promptly treat infections such as EBV and cytomegalovirus (CMV), as these are known triggers for MAS

Drug fever very rarely reported; before attributing fever to drug, make every attempt to exclude more common causes of pyrexia, such as sepsis, in patients with acute leukemia

Mercaptopurine is immunosuppressive and may impair the immune response to infectious agents or vaccines; due to immunosuppression associated with maintenance chemotherapy for ALL, response to all vaccines may be diminished and there is a risk of infection with live virus vaccines; consult immunization guidelines for immunocompromised patients

Therapy can cause fetal harm when administered to a pregnant woman; pregnant women who receive mercaptopurine have an increased incidence of miscarriage and stillbirth; advise pregnant women of potential risk to fetus

There are no data on presence of mercaptopurine or metabolites in human milk, effects on breastfed child or on milk production