Bronchodilators: Definition, Mechanism & Clinical Use

What Are Bronchodilators?

Bronchodilators are medications that relax bronchial smooth muscle, dilating airways to improve airflow. They are first-line therapy for bronchoconstriction in asthma, COPD, and other obstructive lung diseases.

Mechanism

• Beta-2 agonists (SABA/LABA): Stimulate β2 receptors → smooth muscle relaxation.
• Anticholinergics (SAMA/LAMA): Block muscarinic receptors → reduce bronchoconstriction.
• Methylxanthines (theophylline): Phosphodiesterase inhibition, adenosine antagonism.

Delivery Methods

• Metered-dose inhaler (MDI)
• Dry powder inhaler (DPI)
• Nebulizer
• Oral/IV (less common, acute settings)

Selection depends on disease severity, patient factors, and guideline recommendations.