The add-on effect of an intranasal antihistamine with an intranasal corticosteroid in Japanese cedar pollinosis

Objective: Combination intranasal drugs with a corticosteroid and antihistamine are available in several countries with better effect than treatments with single agents. However, it remains unclear whether this effect is also seen in Japanese cedar pollinosis (JCP), the most prevalent seasonal allergic rhinitis in Japan. We investigated the effect of an add-on intranasal antihistamine with an intranasal corticosteroid in JCP during the pollen dispersal period. (UMIN000025508) Methods: We performed a double-blinded, randomized, placebo-controlled trial from March 1 to 14, 2017. Patients (n = 20 per group) received either a mometasone furoate nasal spray (MFNS) plus a levocabastine nasal spray (levocabastine group) or MFNS plus a placebo nasal spray (placebo group). The primary endpoint was the difference in the total nasal symptom score (TNSS) after treatment between the two groups. Differences in the total ocular symptom score, total symptom score, total medication score, total symptom-medication score, and five individual symptoms as well as safety were the secondary endpoints. Results: The change in the TNSS from baseline was significantly greater in the levocabastine group than in the placebo group. A significant reduction in the TNSS was observed more than 6 days earlier in the levocabastine group than in the placebo group. Such add-on effects were also seen in the secondary endpoints. Both treatments were well-tolerated. Conclusion: The intranasal antihistamine provided better control of not only nasal symptoms, but also of ocular symptoms, and decreased the need for rescue medications when added to intranasal corticosteroid treatment in JCP patients.