Controlled trial of H1 antagonists in the treatment of chronic idiopathic urticaria.

The efficacy of astemizole, diphenhydramine, and hydroxyzine hydrochloride in the treatment of chronic idiopathic urticaria was evaluated in this 3-month double-blind, randomized, parallel group study. Thirty-six adult patients were randomly assigned, 13 to the astemizole group (10 mg daily), 12 to the diphenhydramine group (25 mg t.i.d.), and 11 to the hydroxyzine hydrochloride group (25 mg t.i.d.). Demographic data were statistically similar for all variables assessed in the three treatment groups. Seven (58%) of the diphenhydramine patients withdrew before the end of the study, six because of lack of efficacy and one because of drowsiness. Two (18%) of the hydroxyzine hydrochloride patients withdrew, one because of lack of efficacy and one because of drowsiness. Two patients (15%) in the astemizole group withdrew, one because of adverse reaction, and the other because of lack of efficacy. Mean total symptom scores and mean individual symptom scores were lower in the astemizole group than in the other two groups. Wheal area measurements (0.1 mg/mL histamine challenge) decreased more in the astemizole and hydroxyzine hydrochloride groups than in the diphenhydramie group (P = .02). With regard to symptoms, 12/13 patients in the astemizole group improved clinically during their treatment period, versus 8/11 in the hydroxyzine hydrochloride group and 5/12 in the diphenhydramine group. The mean time to first observed therapeutic effect (maintained for three consecutive days) was 5.5 days in the astemizole group, 10.9 days in the hydroxyzine hydrochloride group, and 7.2 days in the diphenhydramine group. In this study, astemizole was as effective as hydroxyzine in patients treated for chronic idiopathic urticaria.