A Review of Inpatients with Adverse Drug Reactions to Allopurinol

BP Khoo, YH Leow
Correspondence: Dr B P Khoo

ABSTRACT
Allopurinol is still an effective uric-acid lowering drug since its introduction in 1963. However it has been frequently incriminated for severe adverse drug reactions. From our retrospective review of 13 inpatients with allopurinol adverse reactions seen over 3 years, fever and rash were the commonest presenting symptoms, occurring several weeks after initiation of the drug. Other associated abnormalities included leukocytosis (62% of patients), eosinophilia (54%), renal impairment (54%) and liver dysfunction (69%). Although 12 patients (92%) met the criteria for allopurinol hypersensitivity syndrome, there was no mortality recorded. The indications for initiating allopurinol therapy were frequently unclear. In view of the severe adverse reactions experienced with allopurinol, we propose that it should only be prescribed when truly indicated.

Keywords: allopurinol, adverse drug reactions, gout and hyperuricemia, multi-organ involvement
Singapore Med J 2000; 41(4): 156-160