Leukemias, lymphomas, and other hematologic cancers:
Indications for Mercaptopurine:
Maintenance therapy of acute lymphatic leukemia as part of a combination regimen.
Adults and Children:
Individualize. Usual range: 1.5–2.5mg/kg/day as a single dose. Concomitant allopurinol: reduce mercaptopurine to ⅓–¼ of the usual dose. TPMT- or NUDT15-deficient, renal or hepatic impairment: reduce dose (see full labeling).
Prior resistance to mercaptopurine.
Not effective in CNS leukemia, acute myelogenous leukemia, chronic lymphocytic leukemia, the lymphomas (including Hodgkin's disease), or solid tumors. Myelosuppression; monitor CBCs weekly and adjust dose for severe cytopenias. Consider testing for TPMT and NUDT15 deficiency in patients who experience severe bone marrow toxicities or repeated myelosuppression. Monitor serum transaminase, alkaline phosphatase, and bilirubin levels at weekly intervals when starting therapy, then monthly thereafter; interrupt treatment if evidence of hepatotoxicity occurs. Concomitant other hepatotoxic drugs or with pre-existing liver disease; monitor LFTs more frequently. Immunosuppression. Inflammatory bowel disease. Renal or hepatic impairment. Elderly. Pregnancy (Cat. D; esp. 1st trimester), nursing mothers: not recommended.
Increased risk of bone marrow suppression with allopurinol, aminosalicylate derivatives (eg, olsalazine, mesalazine, sulphasalazine), trimethoprim-sulfamethoxazole. May antagonize warfarin. Caution with concomitant hepatotoxic agents.
Myelosuppression, hyperuricemia/hyperuricosuria, GI upset, intestinal ulceration, rash, hyperpigmentation, alopecia, oligospermia; hepatotoxicity, infection, immunosuppression.