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 pr otective effect against bronchoconstriction induced by several indirec t stimuli, including ultrasonically nebulized distilled water (UNDW). Since there is a close parallel between its experimental effects and t hose reported for cromolyn, it has been suggested that they may share some common mechanisms of action, Their protective effect, however, ha s never been compared directly. In this study, therefore, we have inve stigated 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 r esponse to UNDW were enrolled in a randomized, double-blind, placebo-c ontrolled study. Treatments were administered five minutes prior to in creasing outputs of UNDW and the response was expressed as the provoca tive output causing a 20% fall in FEV(1) (PO20, in mL/min) and as the output-response slope. Results: Geometric mean PO20 increased from 1.5 3 to 4.05 mL/min (P < .0004) after furosemide. After inhaling the high est output of UNDW (5.2 mL/min), PO20 was not measurable in six of ten patients when pretreated with furosemide and in all patients when pre treated with cromolyn. This difference was statistically significant ( P < .05). Geometric mean values of output-response slope significantly decreased from 13.6 to 2.97 after furosemide (P < .0001) and from 13. 6 to 1.43 (P < .0002) after cromolyn. Conclusions: These results sugge st that cromolyn has a slightly greater anti-reactive activity in UNDW -induced bronchoconstriction compared to furosemide.