Increasing the dose of cetirizine may lead to better control of chronic idiopathic urticaria: an open study of 21 patients

SIR, Chronic idiopathic urticaria (CIU) is characterized by the occurrence of spontaneous pruritic weals on most days. It is common, but often disabling because of persistent clinical symptoms which negatively influence the quality of life. Antihistamines have been the mainstay of treatment and they produce a good response in most patients, but not in all. For those patients who derive only limited benefit from the initial treatment, therapeutic guidelines advocate the use of antihistamines above the licensed or manufacturers’ recommended doses. However, there is scant evidence regarding the effectiveness of dose increases of the same antihistamine in the patients who responded poorly to the first dosage of the agent. Cetirizine is a second-generation antihistamine effective in treating patients with CIU. The manufacturer’s recommended dosage is 10 mg daily and it is permissible to increase the dose up to 20 mg daily. As cetirizine inhibits histamine-induced weal and flare reactions dose-dependently, it is plausible that higher doses of the drug will be more effective in controlling urticarial symptoms. However, the clinical effect of such dose increases has not been evaluated in patients with CIU. In some previous studies, patients with CIU were initially treated with cetirizine 5 mg, and they were allowed to increase the dose to 10 or 20 mg if no benefit was obtained at the starting dose. However, neither urticarial activity at each dose nor clinical effects of the dose increase were assessed in these studies. In the present open study, we evaluated the effect of increasing the dose of cetirizine in order to control the disease activity in patients with CIU, who had derived only limited benefit from 10 mg daily of the same drug. Patients with CIU (> 1 month duration) were recruited from secondary care hospitals. Patients with physical urticaria, or urticaria caused by medications, foods or other known causes were excluded. Prior to the dose-increasing study, patients were treated with cetirizine 10 mg daily for 1 or 2 weeks as a screening period. Twenty-one patients who responded poorly to the treatment, i.e. the change of the total daily score of urticarial symptoms (see below) was less than 1, during the screening period, were enrolled in the study. Approximately one-third of patients who entered the screening period were eligible. At the beginning of the study, patients were randomly assigned to group A (11 patients) or group B (10 patients), after obtaining informed consent, and all patients were given an increased dose of cetirizine, 20 mg daily (10 mg twice daily), for 1 or 2 weeks (period 1). Thereafter, patients in group A continued the daily dosage of cetirizine 20 mg, whereas the patients in group B received the decreased dosage of 10 mg, for an additional 1 to 2 weeks (period 2). Patients were instructed to record daily urticarial activity scores throughout the study period including the screening period. The urticarial activity was assessed by using the scoring system as previously described. Namely, each of the number of weals, the duration of the weals, and the severity of itch, was scored from 0 to 3. The total daily score of the urticarial symptoms, therefore, ranged from 0 to 9. For the assessment of the clinical effect of increase ⁄decrease in the dosage, the data were analysed by the Friedman test and the Steel–Dwass test. There were no statistically significant differences between the two groups in age (42Æ5 ± 14Æ1 vs. 36Æ9 ± 16Æ7 years, mean ± SD, for groups A and B, respectively) or mean urticarial activity scores during the screening period [weal scores 1Æ09 ± 0Æ78 vs. 1Æ11 ± 0Æ64, itch scores 1Æ53 ± 0Æ89 vs.