Drug Safety
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Allopurinol is the primary therapy for the management of chronic gout. Utilization of allopurinol has increased in tandem with the growing prevalence of gout globally. This exposes more patients to the risk of allopurinol hypersensitivity (AH), a rare adverse reaction characterised by a spectrum of cutaneous reactions and systemic manifestations. Severe forms of AH have been associated with high mortality. The pathophysiology underlying this reaction remains unknown, but several risk factors have been proposed. ⋯ Risk factors associated with AH, such as concomitant diuretic use, pre-existing renal impairment and recent initiation of allopurinol, were commonly present in AH patients; however, their role in the mechanism of AH remains to be established. A clear risk factor was the HLA-B*5801 status; this was especially relevant in Asian populations where there is a higher carriage rate of the allele. High allopurinol dose, previously suggested to be a risk factor, was not confirmed as such. The paucity of well-documented case reports and studies of AH render it difficult to draw more concrete conclusions or construct a meticulous profile of patients at risk of AH. Future case reports of AH need to be better documented to contribute to understanding the risks for, and mechanisms of, AH.