Author(s): Chohan S
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Abstract OBJECTIVE: Allopurinol, a purine base analog inhibitor of xanthine oxidase (XO) activity, remains the standard for pharmacologic urate-lowering management of gout. Allopurinol is efficacious and safe in most patients, but intolerance is estimated to occur in up to 10\% of treated patients. Severe or life-threatening allopurinol adverse reactions (AE) occur much less frequently, and include severe cutaneous allopurinol reactions, vasculitis, and/or a multisystem allopurinol hypersensitivity syndrome. During clinical development of febuxostat (FEB), a recently approved non-purine analog inhibitor of XO, subjects with severe allopurinol intolerance were excluded from randomized double-blind FEB/allopurinol comparative trials. METHODS: In this retrospective study, safety and urate-lowering efficacy of FEB was assessed in 13 successively encountered gout patients with prior documented severe allopurinol reactions. RESULTS: FEB was well tolerated in 12 of 13 patients, each of whom remains on treatment. One patient previously hospitalized with documented exfoliative erythroderma during allopurinol treatment, developed biopsy-confirmed cutaneous leukocytoclastic vasculitis. None of the other 12 patients treated with FEB showed rash, worsening hepatic function, blood cytopenia or eosinophilia. CONCLUSION: In 12 of our 13 gout patients with previously documented severe allopurinol AE, FEB treatment was safe. However, the development of a hypersensitivity type cutaneous vasculitis (likely but not definitively FEB-related) early in treatment mandates caution, careful dose escalation, and close monitoring when FEB urate-lowering therapy of allopurinol-intolerant patients is considered.
This article was published in J Rheumatol
and referenced in Journal of Allergy & Therapy