Effect of pre-treatment with inhaled furosemide on allergen nasal challenge.

The inhalation of furosemide has been reported to inhibit the bronchospasm induced by several agents. In the present study, we evaluated the effect of inhaled furosemide on the specific nasal challenge test in patients with allergic rhinitis. A total of 21 consecutive patients with allergic rhinitis (positive skin test and RAST) and a positive basal nasal provocation test (NPT) with the specific allergen were investigated. In each patient, we compared the changes in nasal air-flow (anterior rhinomanometry) during NPT after inhalation of placebo and 20 mg furosemide. The previously positive NPT response to the inhalation of the specific allergen became negative after the furosemide pretreatment in 16 patients (76.2%, p < 0.001, chi-square test). The nasal air flows during NPT were significantly increased after furosemide treatment with respect to placebo inhalation (F = 17.2, d.f. = 1 and 3; p < 0.03; covariance analysis). Our results suggest that the pretreatment with inhaled furosemide in atopic subjects is able to exert a protective effect on the nasal mucosa reactivity to the specific allergen. Therefore, the anti-reactive effect of the drug on the airways is not confined to the bronchial asthmatic response.