[Effect of a leukotriene antagonist, pranlukast hydrate, on exercise-induced asthma for 14 days]

Exercise is a common stimulus of bronchoconstriction in subjects with asthma. Exercise-induced asthma (EIA) may be caused by heat loss and/or water loss during exercise. These changes cause the release of mediators and the development of bronchoconstriction. Recent studies have implicated the cysteinyl leukotrienes in the pathogenesis of EIA. Therefore we investigated the effect of a leukotriene antagonist, pranlukast hydrate, on EIA. Subjects were 11 EIA positive patients and were all atopic type bronchial asthma. 450 mg of pranlukast hydrate was given for 14 days and the exercise test was performed before and after treatment. Pulmonary function tests were done before and 0, 5, 15 and 30 min after completion of the each exercise. Prostaglandin E2, thromboxane B2, leukotriene E4 and B4 in urine were measured before and after the treatment. Pranlukast hydrate did not affect FEV1.0, PF and Flow volume curve at rest and also levels of mediators in urine. The mean maximal percentage fall in FEV1.0 after exercise was--54.9 +/- 5.7% without therapy and--30.1 +/- 7.5% after pranlukast hydrate therapy. There was a significant difference between FEV1.0 values before and treatment at each time (p < 0.05). This study demonstrated that pretreatment with a potent and selective leukotriene antagonist, pranlukast hydrate, attenuated EIA, and it suggests that leukotriene plays a role in EIA.