Risk of cutaneous adverse events with febuxostat treatment in patients with skin reaction to allopurinol. A retrospective, hospital-based study of 101 patients with consecutive allopurinol and febuxostat treatment.

Objective: To investigate the cutaneous tolerance of febuxostat in gouty patients with skin intolerance to allopurinol.

Methods: We identified all gouty patients who had sequentially received allopurinol and febuxostat in the rheumatology departments of 4 university hospitals in France and collected data from hospital files using a predefined protocol. Patients who had not visited the prescribing physician during at least 2 months after febuxostat prescription were excluded. The odds ratio (OR) for skin reaction to febuxostat in patients with a cutaneous reaction to allopurinol versus no reaction was calculated. For estimating the 95% confidence interval (95% CI), we used the usual Wald method and a bootstrap method.

Results: In total, 113 gouty patients had sequentially received allopurinol and febuxostat; 12 did not visit the prescribing physician after febuxostat prescription and were excluded. Among 101 patients (86 males, mean age 61±13.9 years), 2/22 (9.1%) with a history of cutaneous reactions to allopurinol showed skin reactions to febuxostat. Two of 79 patients (2.5%) without a skin reaction to allopurinol showed skin intolerance to febuxostat. The ORs were not statistically significant with the usual Wald method (3.85 [95% CI 0.51-29.04]) or bootstrap method (3.86 [95% CI 0.80-18.74]).

Conclusion: The risk of skin reaction with febuxostat seems moderately increased in patients with a history of cutaneous adverse events with allopurinol. This moderate increase does not support the cross-reactivity of the two drugs.