title: Treatment of gout in a renal transplant patient leading to severe thrombocytopenia.
abstract: OBJECTIVE
  Allopurinol (AP) inhibits the xanthine oxidase, which may indirectly lead to myelotoxicity when used in combination with azathioprine (AZA).
  
  
  METHODS
  A 79-year-old female developed symptomatic thrombocytopenia after combination therapy with AZA (75 mg/day) and AP (100 mg/day) - after AP had been stopped. Concentrations of the myelotoxic 6-thioguanine-nucleotides metabolite of AZA were increased. Thrombocyte counts normalized within 8 days of discontinuation of AZA.
  
  
  CONCLUSIONS
  The effect of a drug interaction in a patient with decreased elimination capacity may take several weeks to become apparent and may in fact do so even after the drug has been stopped. Concurrent AZA and AP therapy demands cautious use.
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Weiler
authors.forename: N
authors.initials: N
authors.lastname: Aellig
authors.forename: I
authors.initials: I
authors.lastname: Fauchère
authors.forename: A
authors.initials: A
authors.lastname: Jetter
authors.forename: N
authors.initials: N
authors.lastname: Corti
mesh_terms: D000368:Aged; D000493:Allopurinol / Q000008:administration & dosage / Q000009:adverse effects*; D001379:Azathioprine / Q000008:administration & dosage / Q000009:adverse effects; D003937:Diagnosis, Differential; D005260:Female; D006073:Gout / Q000188:drug therapy*; D006074:Gout Suppressants / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects; D016030:Kidney Transplantation; D012720:Severity of Illness Index; D013921:Thrombocytopenia / Q000139:chemically induced / Q000175:diagnosis* / Q000473:pathology
chemical_list: D006074:Gout Suppressants; D007166:Immunosuppressive Agents; D000493:Allopurinol; D001379:Azathioprine
keywords: 6-thioguanine-nucleotides; adverse reaction; allopurinol; azathioprine; drug interaction; pharmacodynamics