Effect of inhaled furosemide on the bronchial response to methacholine and cold-air hyperventilation challenges

Inhaled furosemide has been recently demonstrated to inhibit the bronchoconstrictive effects of exercise, ultrasonically nebulized distilled water, and antigen challenge. The presumed mechanism of action of these challenges is through mast cell degranulation. We report on the effect of inhaled furosemide on cold-air hyperventilation challenge (CAHC) and methacholine challenge. We studied 10 subjects with mild to moderate asthma in a double-blind, placebo-controlled, crossover study. Inhaled furosemide did not affect FEV₁ in the hour after inhalation, and there was no significant difference between placebo or furosemide on the dose of methacholine causing a 20% fall in FEV₁. Our results demonstrated inhaled furosemide significantly attenuated the bronchoconstrictive effect at 6 and 9 minutes after CAHC (p <0.05 and 0.029, respectively) when furosemide was compared to placebo and approached significance at 12 and 15 minutes after CAHC (p = 0.052 and 0.56, respectively). Inhaled furosemide attenuates CAHC but does not effect methacholine-induced bronchoconstriction.