Effect of Inhaled Furosemide and Cromolyn on Bronchoconstriction Induced by Ultrasonically Nebulized Distilled Water in Asthmatic Subjects

Background Inhaled furosemide has been shown recently to produce a protective effect against bronchoconstriction induced by several indirect stimuli, including ultrasonically nebulized distilled water (UNDW). Since there is a close parallel between its experimental effects and those reported for cromolyn, it has been suggested that they may share some common mechanisms of action. Their protective effect, however, has never been compared directly. In this study, therefore, we have investigated the ability of equal doses (30 mg) of inhaled furosemide and cromolyn to modulate bronchoconstriction induced by UNDW in a group of ten asthmatic patients. Methods Subjects with documented bronchial response to UNDW were enrolled in a randomized double-blind, placebo-controlled study. Treatments were administered five minutes prior to increasing outputs of UNDW and the response was expressed as the provocative output causing a 20% fall in FEV 1 (PO 20 , in mL/min) and as the outputresponse slope. Results Geometric mean PO 20 increased from 1.53 to 4.05 mL/min ( P 20 was not measurable in six of ten patients when pretreated with furosemide and in all patients when pretreated with cromolyn. This difference was statistically significant ( P P (P .0002) after cromolyn. Conclusions These results suggest that cromolyn has a slightly greater antireactive activity in UNDW-induced bronchoconstriction compared with furosemide.