The Effect of Indomethacin on Exercise-Induced Bronchoconstriction and Refractoriness after Exercise1–3

Exercise causes bronchoconstriction in asthmatic subjects, which is usually followed by a refractory period during which exercise of the same intensity will cause less bronchoconstriction. This study examined the role of contractile prostaglandins in the initial bronchoconstriction after exercise and the role of inhibitory prostaglandins in the refractoriness after exercise. Subjects were pretreated with indomethacin, 50 mg twice daily, on 1 occasion or placebo on 2 occasions for 3 days. This was followed by 2 exercise challenges on a bicycle ergometer at least 30 min apart. Indomethacin did not alter the initial bronchoconstriction after exercise. The maximal fall in FEV1 after the first exercise challenge after placebo was 0.67 +/- 0.17 L and 0.68 +/- 0.17 L, and after indomethacin it was 0.67 +/- 0.12 L. Indomethacin, however, did prevent refractoriness after exercise. The maximal fall in FEV1 after the second exercise challenge after placebo was 0.31 +/- 0.06 L and 0.36 +/- 0.12 L, and after indomethacin it was 0.64 +/- 0.12 L. These results indicate that indomethacin pretreatment does not alter bronchoconstriction after exercise, and they also indicate that indomethacin pretreatment prevents refractoriness after exercise in asthmatic subjects.