EFFECTS OF THROMBOXANE A(2) ANTAGONIST ON AIRWAY HYPERRESPONSIVENESS,EXHALED NITRIC-OXIDE, AND INDUCED SPUTUM EOSINOPHILS IN ASTHMATICS

We examined effects of a thromboxane A(2) (TXA(2)) antagonist seratrod ast on airway hyperresponsiveness, exhaled nitric oxide (NO), and eosi nophils in induced sputum in 14 asthmatics. Subjects were administered 80 mg of seratrodast once a day for 4 weeks. Respiratory conductance (Grs) was measured by the forced oscillation method and airway respons iveness was evaluated as the inhaled dose of methacholine, which induc ed 35% decrease in Grs. Subjects breathed into a Teflon bag, and NO co ncentration in the bag was measured by a chemiluminescence analyzer. I nduced sputum comprised the entire expectorate produced during a 20 mi n inhalation of 3% saline, and was analyzed for total and differential cell counts. Airway hyperresponsiveness was significantly decreased b y seratrodast. By contrast, no differences in either exhaled NO or per centage of eosinophils in sputum were observed before or after seratro dast. We conclude that seratrodast may attenuate airway hyperresponsiv eness, presumably by antagonizing TXA(2) released from the inflamed ai rways.