Clinical and pathophysiological evaluation of tranilast in patients with pollinosis: the effects of pre-seasonal treatment.

Tranilast is an orally effective anti-allergic agent evaluated for clinical activity in prevention of symptoms of allergic rhinitis. It was investigated in a randomized, pre-seasonal, and in-seasonal treatment of tranilast to test the clinical efficacy and pathophysiological changes on the onset of nasal symptoms in season. Thirty-eight patients with a history of Sugi pollinosis and positive allergic tests were treated with tranilast 300 mg daily 6 to 7 weeks before the onset of the pollen season and continuously during the season or no medication including tranilast until the onset of clinical symptoms in season. The number of sneezing and the grade of stuffiness at the onset of pollen season were inhibited significantly in pre-seasonal treatment. The number of mast cells and eosinophils in season increased compared with off-season and the threshold of nasal hypersensitivity in season decreased compared with off-season in inseasonal treatment, but not in pre-seasonal treatment. This study indicates that tranilast may have the prophylactic effect for Sugi pollinosis.