• Acute Lymphoblastic Leukemia (ALL):
    • Maintenance therapy in combination with other chemotherapy agents
    • Also used in initial treatment phases
  • Off-label:

    • Inflammatory Bowel Disease (IBD) — especially Crohn’s disease and ulcerative colitis

Dose:1.5 to 2.5 mg/kg/day orally

Note: TPMT or NUDT15 genetic testing may guide dosing to reduce toxicity risk

  • PO:50 mg
  • Oral Suspension (available in some regions):20 mg/mL
  • Take orally once daily
  • Take at the same time every day
  • Can be taken with or without food, but stay consistent
  • Do not crush or chew the tablet
  • Monitor CBCs and liver function regularly
  • Class: Purine antimetabolite, antineoplastic
  • Mechanism of Action:
  • Mercaptopurine interferes with DNA and RNA synthesis by mimicking purine bases
  • Inhibits proliferation of rapidly dividing cells, particularly leukemic cells
  • Pharmacokinetics:
    • Metabolism: Liver (via TPMT and xanthine oxidase)
    • Half-life: ~1 hour (but intracellular metabolites persist longer)
    • Excretion: Renal (as inactive metabolites)
  • Bone marrow suppression (↓ WBC, RBC, platelets)
  • Nausea, vomiting
  • Anorexia
  • Diarrhea
  • Fatigue
  • Hypersensitivity to mercaptopurine
  • Concurrent use with febuxostat (xanthine oxidase inhibitor — ↑ risk of toxicity)
  • Severe hepatic impairment (relative contraindication)
  • Allopurinol (xanthine oxidase inhibitor):
    • ↓ Mercaptopurine dose to 25–33% of usual to avoid toxicity
  • Febuxostat: Contraindicated
  • Warfarin: May decrease anticoagulant effect
  • Live vaccines: Avoid due to immunosuppression

                                   Drug Status

Availability
Pregnancy
Breastfeeding
Schedule
BRAND NAME STRENGTH FORMULATION PACK SIZE MANUFACTURER DISTRIBUTOR
Purinethol 50mg Tablet 25’s Aspen Pharmacare Beta Healthcare