Airway and Cardio Vascular Responses to Nebulized Glyceryl Trinitrate in Normal Subjects

Background: Glyceryl Trinitrate (GTN) is a potent smooth muscle relaxant and vasodilator. There are conflicting reports regarding its efficacy as a bronchodilator. The aim of this study was to examine the effect of nebulized GTN on airway calibare and cardio vascular system in normal subjects. Methods: We studied 24 normal subjects (6 female) on two occasions, administering either nebulized GTN 6 mg or placebo in a double-blind, randomized, crossover fashion. Bronchial response was assessed by measurement of FEV1. Results: A systemic effect of this dose of GTN was demonstrated by a supine to erect increase in heart rate of 36.0 (8.6) % mean (95% CI) after GTN compared with 16.2 (6.1) % after placebo. Systolic Blood Pressure (BP) decreased by 8.0 (3.8) % after GTN compared with 1.4 (2.8) % after placebo. Diastolic BP did not change. Baseline FEV1 did not differ on the two study days. There was no acute bronchodilator effect. Conclusions: Nebulized GTN has cardio vascular effects but does not have any bronchodilator effect in normal subjects. Further investigation in airways disease is justified.