Exercise-induced bronchoconstriction: elucidating the roles of leukotrienes and prostaglandins.

Exercise-induced bronchoconstriction (EIB) is prevalent among patients with symptomatic asthma, especially those with moderate-to-severe airway hyperresponsiveness. This phenomenon generally manifests within the first 3-5 minutes after exercise, during which the forced expiratory volume in 1 second (FEV1) markedly decreases. Usually, the FEV1 gradually returns to baseline within an hour. Exercise should not be avoided in patients with asthma, since improved physical fitness can reduce the minute ventilation associated with a given exercise work rate and, thereby, reduce the bronchoconstrictive response. The cysteinyl leukotrienes are becoming recognized as important mediators in EIB, and prostaglandins (released at least partially as a result of leukotriene stimulation) are gaining recognition for their protective effects. Thus, pharmacologic agents that either reduce leukotriene activity or enhance prostaglandin activity, or agents that do both, may enhance prophylaxis against EIB. Currently, beta-agonists and cromolyn sodium are the mainstays of prophylactic therapy for EIB.