Antiallergic asthma effect of ipratropium bromide (Sch 1000) in dogs

Antiasthmatic effect of ipratropium bromide (Sch 1000) which is a quarternary ammonium derivative of atropine was investigated in comparison with atropine in anesthetized dogs. Asthmatic responses were provoked with inhalation of Ascaris suum antigen. Sch 1000 (0.1 ?? 0.3%) and atropine (0.1 ?? 0.3%) were given by inhalation for 10 min prior to or after the antigen inhalation. Pretreatment of Sch 1000 and atropine inhibited the increase in respiratory resistance (Rrs) induced by antigen by 55 ?? 75% and 25 ?? 50%, respectively. After treatment with each drug, the enhanced Rrs was reduced by4O ?? 55% and 35 ?? 40%, respectively. The activity of Sch 1000 was three fold stronger than that of atropine. Sch 1000 and atropine also effectively inhibited the increase in airway secretion produced by antigen, while both drugs in 0.3% solution had no effect on the normal bronchial tone and secretion. The findings suggest that vagal activity is involved in allergy related asthma and inhalations of anticholinergic drugs such as Sch 1000 show promise in the treatment of bronchial asthma.