Dapsone is effective in antihistamine refractory chronic idiopathic urticaria

Publish Online: September 1, 2014

Chronic idiopathic urticaria (CIU) is defined as persistent urticaria greater than 6 weeks in duration without an identifiable cause. Antihistamines are the first line therapy. However, many patients fail to achieve satisfactory control even with higher doses. Subsequently, alternative therapies are often required. Dapsone is a sulfone antibiotic with anti-inflammatory properties, and has shown promise in antihistamine refractory CIU. Evidence of this success, however, has been limited to small case studies and non-blinded trials.

In a study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Morgan and colleagues present their results from the first randomized, placebo-controlled trial of dapsone in patients with antihistamine refractory chronic urticaria.

The double-blind trial involved 22 patients who were refractory to higher-than-standard dosages of antihistamines. After an initial visit to obtain baseline labs, the patients were monitored for one week to ensure adequate urticarial activity. Subjects were randomized to either 100 mg dapsone or placebo for 6 weeks. Then, after a 2-week washout period without any medications, patients were crossed over to the alternative treatment. Daily diaries assessed both hive and itch severity on a scale of 0-3 and these daily scores were summed for a weekly itch score (WIS) and weekly hive score (WHS). The co-primary endpoints were the change from baseline to week 6 in WHS and WIS, utilizing the 1-week screening period as the baseline for the WHS and WIS. Due to a statistically significant treatment carryover effect from dapsone, where administration of the drug first causes continued symptom improvement in subsequent phases, the authors focused their analysis by using the first treatment period only using a parallel design.

After 6 weeks the patients in the dapsone arm showed a mean improvement over baseline in both co-primary endpoints for hive and itch scores. Additionally, a statistically significant improvement was seen by dapsone over placebo for itch (p=0.047) but not for hives (p=0.16). Subjects in the dapsone arm experienced an asymptomatic mean decline in hemoglobin of 1.8 mg/dL, which reversed after cessation of the drug.

Overall, dapsone demonstrated efficacy and was well tolerated, with no serious adverse effects. While this was a small pilot study, the authors concluded that dapsone is an inexpensive alternative agent, and should be considered an option for management of antihistamine refractory CIU patients.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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