Effects of single-dose zileuton on bronchial hyperresponsiveness in asthmatic patients treated with inhaled corticosteroids

The aim of the study was to determine whether zileuton, an inhibitor of 5-lipoxygenase, attenuated bronchial hyperresponsiveness (BHR) in asthmatic subjects who had marked BHE during maintenance treatment with inhaled corticosteroids (ICS). In a randomized, double-blind, placebo-controlled, cross-over study, a challenge test with histamine (provocative concentration of histamine producing a 20% fall in forced expiratory volume in one second (FEV1) (PC20,Hist)) and with ultrasonically nebulized distilled mater (UNDW) (provocative dose of UNDW producing a 20% fall in FEV1 (PD20,UNDW)) was performed in seven patients with asthma after intake of either 400 mg zileuton or placebo, All patients (mean age 33 yrs, mean lipoxygenase inhibitor FEV1 111% of predicted) had marked BHR, as indicated by a mean PD20,UNDW of 4.74 mL under treatment for at least 6 months with up to 800 mu g ICS (mean 536 mu g daily), On four different occasions, separated by at least 5 days, two UNDW and two histamine challenge tests were performed in random order 3 h after a morning dose of either zileuton or placebo, Neither zileuton nor placebo changed baseline airway calibre prior to provocation, Zileuton increased PC20,Hist from 0.99 to 5.64 mg.mL(-1) (2.1 doubling doses; p<0.03 compared to placebo), and increased PD20,UNDW from 3.10 to 9.31 mL (1.3 doubling doses; p<0.05 compared to placebo), In conclusion, a single dose of 400 mg zileuton attenuates bronchial hyperresponsiveness to histamine and ultrasonically nebulized distilled water in asthmatic patients with marked bronchial hyperresponsiveness during treatment with inhaled corticosteroids.