Effect of RG 12525, a new leukotriene antagonist, on pulmonary function of asthmatic adults.

RG 12525 is a new oral leukotriene D4 (LTD4) antagonist with proven activity in animal and human models of leukotriene-induced bronchoconstriction. In this randomized, double-blind, parallel-group, placebo-controlled study the bronchodilator effects of single oral doses of RG 12525 of 25 and 200 mg or placebo were evaluated in 62 adult asthmatic patients. All patients had previously demonstrated 20% reversibility of FEV1 with an inhaled beta-agonist. They had an unmedicated FEV1 less than 80% of predicted value at the time of the study. Bronchodilator activity was assessed by spirometry before and at multiple time points after dosing for eight hours. A single 200-mg dose of RG 12525 of mg resulted in statistically significantly greater increases in mean maximum change above baseline for FEV1 and FEF25-75% than placebo. The peak effect was observed four to five hours after dosing. The RG 12525 dose of 25 mg dose induced better bronchodilation than placebo but the differences were not significant. Adverse clinical experiences or laboratory abnormalities were not noted.