Chronic spontaneous urticaria (CSU) features a spontaneous appearance of wheals, angioedema or both for >6 weeks. Continuous treatment with H1-antihistamines is the first-line treatment for CSU. However, H1-antihistamine treatment caused symptom alleviation in less than 50% of patients with CSU. Guidelines from Japan for the diagnosis and treatment of urticaria advise increasing the H1-antihistamine dose or switching to other H1-antihistamines; however, there is a lack of evidence supporting a switch to other H1-antihistamines in patients with refractory CSU who are unresponsive to H1-antihistamines at the licensed dose.

A multicenter, open-label, noninferiority, randomized, parallel comparison study will determine the efficacy of bilastine 20 mg compared with a twofold H1-antihistamine dose increase in patients with refractory CSU who are unresponsive to H1-antihistamines at the licensed dose. The study will witness an intervention period of 7 days. It will randomize participants (n = 150) to either an increased H1-antihistamine dose or a switch to bilastine 20 mg at a 1:1 ratio and evaluate the mean of the total symptom score of 5 to 7 days after the intervention. Additionally, it will also determine the safety of bilastine 20 mg regarding somnolence contrasting a twofold dose increase of H1-antihistamines by measuring an alteration in the Japanese version of the Epworth Sleepiness Scale from baseline to a week after starting the intervention.

This trial will provide evidence of the efficacy and safety of bilastine after switching treatments in patients with refractory CSU who are unresponsive to H1-antihistamines at the licensed dose.

Source: Fukunaga A, Oda Y, Washio K, et al. Efficacy of switching to bilastine, a histamine H1 receptor antagonist, in patients with chronic spontaneous urticaria (H1-SWITCH): study protocol for a randomized controlled trial. Trials. 2020;21(1):23.