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).

Mercaptopurine Contraindications:

Prior resistance to mercaptopurine.

Mercaptopurine Warnings/Precautions:

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, nursing mothers: not recommended.

Mercaptopurine Classification:

Antimetabolite.

Mercaptopurine Interactions:

Increased risk of bone marrow suppression with allopurinol, aminosalicylate derivatives (eg, olsalazine, mesalazine, sulphasalazine), trimethoprim-sulfamethoxazole. May antagonize warfarin. Caution with concomitant hepatotoxic agents.

Adverse Reactions:

Myelosuppression, hyperuricemia/hyperuricosuria, GI upset, intestinal ulceration, rash, hyperpigmentation, alopecia, oligospermia; hepatotoxicity, infection, immunosuppression.

Note:

Formerly known under the brand name Purinethol.

Metabolism:

Mercaptopurine is inactivated via 2 major pathways: thiol methylation and oxidation.Variability in mercaptopurine metabolism is one of the major causes of interindividual differences in systemic exposure to the drug and its active metabolites.

Drug Elimination:

Half-life is less than 2 hours following a single oral dose. 

46% of dose recovered in the urine (as parent drug and metabolites) in the first 24 hours.

How Supplied:

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