Bronchodilators

• Inhaled bronchodilators are the mainstay of COPD management and include β₂-agonists and anticholinergics (antimuscarinics), which are equally effective.

Examples of bronchodilators

• β₂-agonists relax bronchial smooth muscle (salbutamol)

• Long-acting β₂-agonists (LABAs) are preferable for patients with nocturnal symptoms or for those who find frequent dosing inconvenient (such as salmeterol, formoterol). Recently, 'ultra-long' acting LABAs have been developed that require once-daily dosing (indacaterol)

• Anticholinergics relax bronchial smooth muscle through competitive inhibition of muscarinic receptors (M₁, M₂, and M₃) (such as ipratropium)

• A long-acting quaternary anticholinergic which is M₁ and M₃ selective (tiotropium) may have an advantage over ipratropium as M₂ receptor blockade may limit bronchodilation

Patients with mild (Stage I) disease are treated only when symptomatic. Those with Stage 1 or higher COPD should be taking one or both of these classes of drugs regularly, to increase pulmonary function and exercise capacity.

The frequency of exacerbations can be reduced with the use of anticholinergics, inhaled corticosteroids, or LABAs. The initial choice among short-acting β₂-agonists, LABAs, anticholinergics (which have a greater bronchodilating effect), and combination β₂-agonist and anticholinergic therapy, is often a matter of physician and patient choice.

Reference

1. Global Initiative for chronic obstructive lung disease: Global strategy for the diagnosis, management, and prevention of COPD. 2010. www.goldcopd.org