Effect of acute and chronic inhaled furosemide on bronchial hyperresponsiveness in mild asthma.

We determined whether chronic administration of furosemide aerosol would be beneficial for the treatment of asthma. First, we showed that furosemide aerosol delivered from a metered-dose inhaler (10 and 20 mg) significantly protected against sodium metabisulfite (MBS) challenge by 0.6 and 1.3 doubling dilutions respectively in 12 volunteers with mild asthma. In a double-blind cross-over study, we examined the effect of furosemide aerosol from a twice more efficient metered-dose inhaler (10 mg four times per day) inhaled over 4 wk versus placebo in 12 other asthmatic subjects. There was no significant effect of furosemide on bronchial responsiveness to methacholine or MBS. Treatment with furosemide over 1 mo did not improve bronchial hyperresponsiveness in subjects with mild asthma.