Mercaptopurine
PURINETHOL
What it isPurine analog; acute lymphoblastic leukemia maintenance and inflammatory bowel disease.
Why this oneIt is the backbone of ALL maintenance and is steroid-sparing in IBD.
What limits it⚑ TPMT or NUDT15 deficiency can cause life-threatening myelosuppression, so test first. Allopurinol sharply raises exposure and requires dose reduction.
FDA-approved for
- acute lymphoblastic leukemia
Off-label
- Crohn disease and ulcerative colitis maintenance
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Acute lymphoblastic leukemia (maintenance, combination regimen) | Adults & pediatrics | 1.5–2.5 mg/kg PO QD | Adjust to ANC/tolerability | Titrate to myelosuppression |
Renal CLcr <50 mL/min: use lowest starting dose or increase interval to q36–48h
Hepatic Use lowest starting dose
Instructions
- Take consistently either with or without food
- Do not administer to patients unable to swallow tablets
- Reduce dose to 1/3–1/4 when coadministered with allopurinol
- Reduce starting dose in TPMT/NUDT15 deficiency (homozygous typically ≤10% of dose)
- Cytotoxic drug — follow special handling/disposal
Cautions
- Myelosuppression (anemia, leukopenia, thrombocytopenia); test TPMT/NUDT15 if severe/recurrent
- Hepatotoxicity, including hepatic necrosis; monitor transaminases/ALP/bilirubin
- Immunosuppression; diminished vaccine response, risk with live vaccines
- Treatment-related malignancies (hepatosplenic T-cell lymphoma)
- Macrophage activation syndrome
- Embryo-fetal toxicity
Adverse reactions
- Myelosuppression (anemia, leukopenia, thrombocytopenia)
- Anorexia
- Nausea
- Vomiting
- Diarrhea
- Malaise
- Rash
Pregnancy Can cause fetal harm; increased miscarriage and stillbirth
Lactation Advise not to breastfeed during treatment and for 1 week after last dose
NO BOXED WARNINGS
Principal riskTPMT or NUDT15 deficiency causes severe myelosuppression
Cost, est. cash$50–$10,000/month or cycle
Generic entry2004
Classes and tags
Clinical profile
Legacy pregnancy categoryD
Defining liabilityMyelosuppression and agent-specific hepatic, cardiac, pulmonary, neurologic or reproductive toxicity require oncology monitoring.
Mechanism of action: Mercaptopurine ballicule
