Dapsone

Low-Dose Dapsone in Chronic Idiopathic Urticaria: Preliminary Results of an Open Study

Cassano N, et al. Acta Derm Venereol. 2005;85(3):254-255.

Summary

The authors present an open-label study to determine the efficacy of dapsone in the treatment of chronic idiopathic urticaria. Eleven patients with chronic idiopathic urticaria recalcitrant to treatment with antihistamines were enrolled. Patients were described as having "severe" disease and 3 of the patients also had delayed pressure urticaria. All patients underwent baseline laboratory evaluation, including determination of the glucose-6-phosphate dehydrogenase (G6PD) level. Complete blood cell counts were assessed at 2 weeks after initiation of dapsone, and then monitored every 4 to 6 weeks. Patients were treated with dapsone 25 mg daily and cetirizine 10 mg daily. Study protocol dictated that cetirizine be discontinued once control of symptoms was obtained. Dapsone was to be discontinued no sooner than 4 weeks after resolution of symptoms. Patients were evaluated 2 weeks after beginning treatment and then at monthly intervals. Assessment of patients was subjective. Response to treatment was noted as complete indicating remission, partial indicating improvement, and poor indicating there was no subjective change. If assessment was poor after 4 weeks of treatment, the dose of dapsone was increased to 50 mg daily. Of the 11 patients treated, 9 achieved complete remission within 3 months of treatment with dapsone 25 mg daily. The 3 patients who also had delayed pressure urticaria were among these complete responders. Median time to start of response was 3 to 4 weeks with the majority of patients discontinuing cetirizine after 4 to 6 weeks. Follow-up evaluation was variable among the patients. Seven patients had no relapse. Regarding the 2 patients who were non-responders, complete remission was achieved in one of them after 2 months of treatment with dapsone 50 mg daily. The other had only a partial response. No adverse events or changes in complete blood cell counts were noted.

Comment

This was an open-label study to evaluate the efficacy of dapsone in the treatment of chronic idiopathic urticaria. All patients were described as having severe urticaria, unresponsive to treatment with antihistamines. Complete response was noted in 9 patients within 3 months of beginning treatment with dapsone 25 mg daily and in one patient after 2 months of dapsone 50 mg daily. These results are very encouraging given the relatively small dose of dapsone needed to achieve remission, especially in those described as having severe disease. Although this trial was conducted as an open study, bias is not easily introduced as urticarial lesions are either present or not present and patient evaluation was subjective. The authors do not comment specifically on the length of follow-up for the patients achieving remission so it is unclear how long patients were asymptomatic after discontinuation of dapsone. One patient was noted to have relapsed after 2 years following remission and again achieved a complete response after another 3 months of treatment with dapsone 25 mg daily. Patients were properly screened for G6PD deficiency and had their complete blood cell counts carefully monitored. No adverse events or laboratory abnormalities were noted. Despite being a small study, these results seem to indicate that dapsone is a safe and effective treatment for chronic idiopathic urticaria and merits consideration for patients with refractory disease.

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COPYRIGHT 2005 Journal of Drugs in Dermatology, Inc.
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