Introduction: Allopurinol is, by far, the most frequently prescribed drug for the treatment of hyperuricemia, and the lack of alternatives makes, in case of a reaction, a desensitization procedure to be considered. With this survey, we aimed to do a characterization of patients with hypersensitivity (HS) reactions to allopurinol, who endured desensitization procedures.
Material and methods: Retrospectively, we analyzed the medical files of a group of patients that fit into our objective and were observed in our Department of Immunoallergology of Coimbra University Hospital, between 2007/2012. Demographic data, pathology underlying all prescriptions and concomitant diseases/regular medication, the desensitization protocol and all adverse reactions were taken into consideration.
Results: Six out of seven patients were male, aged from 37 to 79 (mean age of 64 ± 14 years) when undergoing the procedure. As far as the kind of reaction was concerned, three of the patients presented a fixed erythema, two urticaria with/without angiodema, one anaphylaxis and another one maculopapular rash at the time of desensitization. Five of them had gouty joint pathology, one hyperuricemia with chronic renal failure and another had both. Six among all of them presented associated cardiovascular pathology and were polymedicated. \\\\\\\\\\\\\\\\
The desensitization protocol used was adapted from Umpiérrez, with an initial dose of 10 μg up to 300 mg/day, adjusted in case of adverse reaction. There were no complications in three patients and the remaining had mild/ moderate skin reactions. In four patients with HS reaction during desensitization, only three needed to decrease the dose. The maintenance dose was achieved by extending the length of desensitization, between sixteen to twentytwo days.
Conclusion: In this series, the majority of patients had HS reactions during desensitization protocol and dose adjustment was necessary. However, we managed to achieve a maintenance dose in all of them.