Both histamine and cysteinyl leukotrienes play an important role in both seasonal allergic rhinoconjunctivitis (SARC) and asthma. A combination therapy against both was shown to give benefit both in vitro and in vivo. Authors wanted to test the efficacy of combining both montelukast (a leukotriene receptor antagonist) with bilastine (a second-generation antihistamine) as compared to monotherapy with either of them. Adult patients with SARC and partially controlled mild to moderate asthma were included from six European countries. The design was a double-blind, double-dummy, randomised, active-controlled and parallel-group. Outcome measures included the Total Symptom Score, Daytime Nasal Symptom Score, Daytime non-Nasal Symptom Score, asthma quality of life questionnaire, use of rescue medications and occurrence of adverse events. A total of 419 were randomised; most of them have mutli-pollen allergy.
There was no significant difference in outcome or in adverse events between the three arms of the study (bilastine alone, montelukast alone, or the combination of both). The only difference was that the bilastine group showed faster improvement in symptoms as compared to montelukast group.
Authors concluded that SARC response to treatment with bilastine and montelukast was similar to either agent alone. As authors commented, the two issues with the study were the ceiling effect and the absence of a control group. The wide availability of over-the-counter antihistamines makes them the natural choice as first additional treatment to this group of patients, with the assumption that the results of this study could be generalised to other second-generation antihistamines.