Short-Acting β2 Agonists (SABA)

respiratory bronchodilator beta2_agonist saba

Short-acting β2 agonists are rapid bronchodilators used for immediate relief of bronchospasm.

They are the primary rescue medications in obstructive lung disease.

• Albuterol
• Levalbuterol

Receptor

• β2 adrenergic receptor activation

Cellular Effect

• ↑ cAMP
• Smooth muscle relaxation

Physiologic Effects

• Bronchodilation
• ↓ airway resistance
• ↓ mast cell mediator release
• ↑ mucociliary clearance
• Intracellular potassium shift

Net effect:

• Rapid airway opening

Primary uses:

• Acute asthma symptoms
• Exercise-induced bronchospasm
• COPD rescue therapy

Also used for:

• Hyperkalemia (temporary intracellular shift)

SABA should always be paired with controller therapy in persistent asthma:

• Inhaled Corticosteroids

Frequent rescue inhaler use is a marker of worsening airway inflammation — not a need for more bronchodilator.

Dose dependent.

• First drug used in asthma exacerbation
• Spacer improves delivery significantly
• Nebulizer is easier, not stronger
• Overuse predicts hospitalization risk

• β2 Agonists
• Inhaled Corticosteroids
• Asthma
• COPD