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6-mercaptopurine (Purinethol, 6-MP, Mecaleukin, Leukerin, Leupurin)

Tradename: Purinethol. Indications: 1) leukemia 2) Crohn's disease 3) immunosuppression Dosage: 1) 70-100 mg/m2/day 2) reduce by 75% (20-25 mg/m2/day) if used in combination with allopurinol 3) dosage adjustment for renal insufficiency Tabs: 50 mg. Pharmacokinetics: 1) well absorbed orally 2) poor systemic circulation availability 3) systemic availability increased with allopurinol 4) well distributed to tissues 5) metabolized by xanthine oxidase to thioinosinic acid 6) 50% eliminated in the urine 7) 1/2life is 1 hour Adverse effects: 1) common (> 10%) - intrahepatic cholestasis & centrolobular necrosis a) increased AST, alkaline phosphatase, bilirubin b) jaundice 2) less common (1-10%) - hyperpigmentation, rash, hyperuricemia, nausea/vomiting, diarrhea, stomatitis, anorexia, stomach pain, mucositis - renal toxicity, leukopenia, thrombocytopenia, anemia may occur at higher doses - more GI toxic than 6-thioguanine - myelosuppression - moderate (platelets & leukocytes) - onset: 7-10 days - nadir: 14 days - recovery: 21 days 3) uncommon (< 1%) - drug fever, scaling rash, glossitis, tarry stools, eosinophilia 4) other [2] headache Drug interactions: 1) coadministration of allopurinol a) may potentiate myelosuppression b) increases serum concentrations by 60% 2) warfarin 3) Bactrim Laboratory: - consider baseline thiopurine methyltransferase in erythrocytes to assess likelihood of myelosuppression [5] Test interactions: increases serum K+ Mechanism of action: 1) purine antagonist, S-phase specific 2) inhibits DNA & RNA synthesis Mechanism of drug resistance: -> diminished activity of hypoxanthine-guanine phosphoribosyl transferase (HGPRT)

Interactions

drug interactions

Related

hypoxanthine-guanine phosphoribosyltransferase (HGPRT, HPRT, HPRT1)

General

antineoplastic agent (chemotherapeutic agent) mercaptopurine; thiopurine

Properties

MISC-INFO: elimination route KIDNEY

Database Correlations

PUBCHEM correlations

References

  1. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  2. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 533
  4. Wikipedia: Mercaptopurine http://en.wikipedia.org/wiki/Mercaptopurine
  5. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015