3. Bronchi— uses antimuscarinic agents

Parenteral atropine has long been used to reduce airway secretions during general anesthesia. Ipratropium is a quaternary antimuscarinic agent used by inhalation to promote bronchodilation in asthma and chronic obstructive pulmonary disease (COPD). Although not as efficacious as β agonists, ipratropium is less likely to cause tachycardia and cardiac arrhythmias in sensitive patients. It has very few antimuscarinic effects outside the lungs because it is poorly absorbed and rapidly metabolized. Tiotropium is an analog with a longer duration of action. Aclidinium is a newer long-acting antimuscarinic drug available in combination with a long-acting β2-adrenoceptor agonist for the treatment of COPD.