Effects of a thromboxane synthase inhibitor (CS-518) on the eosinophil-dependent late asthmatic response and airway hyperresponsiveness in guinea pigs.

The effects of CS-518, a thromboxane A2 synthase inhibitor, on antigen-induced dual bronchial responses, airway hyperresponsiveness (AHR) and airway eosinophilia were investigated in an experimental guinea pig model of the late asthmatic response. Oral CS-518 (1 and 10 mg/kg) inhibited immediate and late asthmatic responses dose-dependently. It also inhibited AHR and eosinophil accumulation after antigen challenge. Therefore, thromboxane A2 is possibly involved in development of the late asthmatic response and AHR, and CS-518 was inferred to inhibit these via inhibition of eosinophil accumulation and thromboxane production.