Double-blind placebo-controlled trial of dapsone in antihistamine refractory chronic idiopathic urticaria.

Abstract

Management of antihistamine refractory chronic idiopathic urticaria (CIU) has poorly defined therapeutic options. To evaluate the efficacy of dapsone (4,4'-diaminodiphenylsulfone) in antihistamine refractory CIU compared with placebo. Twenty-two patients with antihistamine refractory CIU were randomly assigned to 100 mg of dapsone daily or placebo for 6 weeks in a 14-week double-blind, placebo-controlled crossover trial. End points were measured from a daily diary that reflected the weekly hive score, the weekly itch score, and a visual analog scale (VAS) score. Secondary to a carryover effect, the first period results were analyzed as a parallel design that compared placebo with dapsone directly by using repeated-measures analysis. After 6 weeks, the patients in the dapsone arm showed mean improvement over baseline in VAS (2.3 [95% CI, 0.6-4.1], P = .01), urticaria score (-3.5 [95% CI, -6.2 to -0.9], P = .01), and itch score (-4.8 [95% CI, -7.6 to -2.1], P = .001), whereas the placebo arm showed no improvement over baseline for VAS, urticaria, or itch scores. Dapsone showed greater improvement compared with placebo for itch (P = .047) and VAS (P = .04). Of the 22 patients, 3 showed complete resolution of hives and itch with dapsone, whereas 31% and 41% had ≥ 50% resolution of hives and itch, respectively. No serious adverse effects were observed with dapsone. To our knowledge, this is the first double-blind, placebo controlled study of dapsone in CIU and indicates that dapsone has efficacy in patients with antihistamine refractory CIU.