====== Short-Acting β2 Agonists (SABA) ======

{{tag>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.

<WRAP center round important 70%>
SABA = symptom relief  
They do NOT control inflammation
</WRAP>

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===== Drugs in Class =====

  * [[respiratory:beta2_agonists:albuterol|Albuterol]]
  * [[respiratory:beta2_agonists:levalbuterol|Levalbuterol]]

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===== Mechanism of Action =====

**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

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===== Clinical Role =====

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:
  * [[respiratory:inhaled_corticosteroids:start|Inhaled Corticosteroids]]

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===== Dosing Concept =====

<WRAP center 70%>
^ Situation ^ Meaning ^
| Rare use | Controlled disease |
| >2 days/week | Inadequate control |
| Daily use | Needs escalation |
</WRAP>

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

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===== Adverse Effects =====

^ Effect ^ Mechanism ^
| Tremor | Skeletal muscle β2 stimulation |
| Tachycardia | β1 spillover |
| Hypokalemia | Intracellular potassium shift |
| Anxiety | Adrenergic stimulation |

Dose dependent.

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===== Clinical Pearls =====

<WRAP round tip 90%>
The rescue inhaler measures disease control.

More SABA = more inflammation
</WRAP>

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

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===== Comparison Within β2 Class =====

^ Class ^ Role ^ Duration ^
| [[respiratory:beta2_agonists:saba|SABA]] | Rescue | 4–6 hr |
| [[respiratory:beta2_agonists:laba|LABA]] | Maintenance | 12–24 hr |

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===== Related =====

  * [[respiratory:beta2_agonists:start|β2 Agonists]]
  * [[respiratory:inhaled_corticosteroids:start|Inhaled Corticosteroids]]
  * [[respiratory:asthma|Asthma]]
  * [[respiratory:copd|COPD]]