Effect of nedocromil sodium on SO2-induced airway hyperresponsiveness and citric acid-induced cough in dogs.

In anaesthetized dogs exposed to SO2, nedocromil sodium prevented the increase in bronchial responsiveness to histamine challenge and suppressed the cellular changes taking place in the lung. In conscious dogs challenged with citric acid, by inhalation, nedocromil sodium prolonged the time to onset of coughing and had an inhibitory effect on the total number of coughs in each episode. Nedocromil sodium has been observed to stimulate bronchial C fibers, and it is suggested that this activity may relate to the antitussive effect of the compound.