[Effect of the platelet-activating factor antagonist BN 52063 on exertional asthma]

In a randomised single-blind crossover study we assessed the effects of a specific PAF acether antagonist, BN 52063, on the early asthmatic response to exercise in six patients with exercise induced asthma. After a treatment period of two days an exercise challenge on the third day was preceded by administration of either placebo or BN 52063 240 mg p.o. 3 hours or 5 mg by inhalation 30 minutes before the challenge. After the oral intake of 240 mg BN 52063 there was no effect on the initial exercise induced bronchoconstriction, but the prolonged reduction of PEF was significantly attenuated expressed as a smaller AUC (p less than 0.02). In the placebo period there was a marked increase in plasma concentrations of both platelet factor 4 (PF4) and beta-thromboglobulin (beta-TBG). Intake of BN 52063 diminished the rise in plasma concentrations of PF4 and beta-TBG after the exercise challenge significantly. The results show that platelet activation after exercise induced asthma was markedly inhibited by BN 52063, indicating that PAF acts as a mediator in exercise induced asthma.