6 Mercaptopurine
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Contents |
Introduction
- Tradename: Purinethol.
Indications
Dosage
- 70-100 mg/m2/day
- reduce by 75% (20-25 mg/m2/day) if used in combination with allopurinol
- dosage adjustment for renal insufficiency
- Tabs: 50 mg.
Pharmacokinetics
- well absorbed orally
- poor systemic circulation availability
- systemic availability increased with allopurinol
- well distributed to tissues
- metabolized by xanthine oxidase
- 50% eliminated in the urine
- 1/2life is 1 hour
- elimination via kidney
Adverse-effects
- common (> 10%)
-
- increased AST, alkaline phosphatase, bilirubin
- jaundice
- 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
- uncommon (< 1%)
- drug fever, scaling rash, glossitis, tarry stools, eosinophilia
- other [2] headache
Drug-interactions
- coadministration of allopurinol
- may potentiate myelosuppression
- increases serum concentrations by 60%
Test-interactions
- increases serum K+
Mechanism-of-action
- purine antagonist, S-phase specific
- inhibits DNA & RNA synthesis
- Mechanism of drug resistance:
- diminished activity of hypoxanthine-guanine phosphoribosyl transferase ( HGPRT)
More General Terms
Additional Terms
Internet Database
PubChem: 4071
PubChem: 407010
PubChem: 22491
PubChem: 667490
References
- Kaiser Permanente Northern California Regional Drug Formulary, 1998
- Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
- Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 533
