Cysteinyl leukotriene and
leukotriene receptor occupancy have been linked to several processes in
seasonal allergic rhinitis (SAR), including nasal congestion,
rhinorrhea, and recruitment of inflammatory cells. We investigated whether add-on
loratadine, an
antihistamine, might be effective for SAR patients showing unsatisfactory control of symptoms with the
leukotriene receptor antagonist (LTRA)
montelukast alone. Patients with SAR caused by Japanese cedar pollen (SAR-JCP; mean age, 29.4 years) were given prophylactic
montelukast for 1 month before peak JCP dispersal. Patients recorded the severity of the symptoms (
sneezing,
rhinorrhea, nasal congestion, and ocular symptoms) daily on visual analog scale (VAS). We selected patients with VAS scores of >50 for any of the symptoms just before the peak pollen season (March 2 to March 8) and designated them as "poorly controlled" patients. Then, in the peak JCP season (from March 9), we conducted a randomized, double-blind, placebo-controlled study to determine whether add-on
loratadine might be effective for these "poorly controlled" patients.
Montelukast alone was effective, as evaluated by improvement of the VAS scores, in 95 of the 137 patients (69.3%). Add-on
loratadine significantly decreased the total scores for nasal symptoms (p < 0.05),
sneezing (p < 0.05), and
rhinorrhea (p < 0.05) when compared with placebo. The symptoms of SAR in two of three SAR-JP patients could be controlled (VAS score[s] under 50) by prophylactic treatment with
montelukast alone under the condition of mild JCP dispersal. Furthermore, the effect of add-on
antihistamine on
sneezing and
rhinorrhea was found in selected SAR-JCP patients.