The effect of an oral leukotriene antagonist L-649,923 on histamine and leukotriene D4-induced bronchoconstriction in normal man.

We have studied the effect of prior treatment with an oral leukotriene (LT) antagonist L-649,923, on histamine and LTD4-induced bronchoconstriction in 12 normal male subjects in a double-blind, placebo-controlled, randomized, crossover trial. L-649,923 had no effect on histamine-induced bronchoconstriction but antagonized LTD4-induced bronchoconstriction, causing a mean shift to the right of the dose-response curves of 3.8-fold. This study demonstrates that LT antagonism is possible and safe in man and that LTD4-inhalation challenge testing can be used to detect LT antagonism.