A 68-year-old woman with chronic obstructive pulmonary disease (COPD) and acute exacerbation presents with severe bronchospasm. Which beta-2 adrenergic agonist is the drug of choice for acute relief in this setting?

Question

Accepted Answer

A. Salbutamol. ## Beta-2 Agonist Selection in Acute Bronchospasm

**Key Point:** Salbutamol (albuterol) is the gold-standard short-acting beta-2 agonist (SABA) for acute bronchospasm due to its rapid onset and short duration of action.

### Pharmacodynamic Properties Required for Acute Relief

| Property | Requirement | Salbutamol | Salmeterol | Formoterol | Vilanterol |
|----------|-------------|-----------|-----------|-----------|------------|
| **Onset of action** | Rapid (< 5 min) | 5–15 min | 10–20 min | 1–3 min | 1–3 min |
| **Duration** | Short (4–6 hrs) | 4–6 hrs | 12 hrs | 12 hrs | 24 hrs |
| **Receptor selectivity** | β2 >> β1 | Excellent | Excellent | Excellent | Excellent |
| **Indication** | Acute relief | **Yes** | No | No | No |
| **Indication** | Maintenance | No | Yes | Yes | Yes |

**High-Yield:** **SABA = Short-Acting Beta-2 Agonist** for acute symptoms. **LABA = Long-Acting Beta-2 Agonist** for maintenance. Never use LABA monotherapy in COPD (increased mortality risk).

### Why Salbutamol is Preferred in Acute Exacerbation

1. **Rapid onset:** Begins working within 5–15 minutes via β2-mediated smooth muscle relaxation
2. **Short duration:** Allows frequent dosing (every 4–6 hours) without accumulation
3. **Reversible binding:** Quickly dissociates from receptor, permitting dose titration
4. **Inhaled route:** Delivers high local concentration to airways with minimal systemic effects

**Clinical Pearl:** In acute exacerbation, salbutamol can be given via nebulizer (2.5–5 mg) or MDI (100 mcg/puff) every 15–30 minutes for the first hour, then every 4–6 hours. This flexibility is unique to SABAs.

**Mnemonic:** **SABA-LABA rule** — **S**hort-acting for **A**cute, **L**ong-acting for **L**ong-term (maintenance).

[cite:KD Tripathi 8e Ch 27]

Answer

B. Vilanterol

Answer

C. Salmeterol

Answer

D. Formoterol

A 68-year-old woman with chronic obstructive pulmonary disease (COPD) and acute exacerbation presents with severe bronchospasm. Which beta-2 adrenergic agonist is the drug of choice for acute relief in this setting?

Explanation

Beta-2 Agonist Selection in Acute Bronchospasm

Pharmacodynamic Properties Required for Acute Relief

Why Salbutamol is Preferred in Acute Exacerbation

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Property	Requirement	Salbutamol	Salmeterol	Formoterol	Vilanterol
Onset of action	Rapid (< 5 min)	5–15 min	10–20 min	1–3 min	1–3 min
Duration	Short (4–6 hrs)	4–6 hrs	12 hrs	12 hrs	24 hrs
Receptor selectivity	β2 >> β1	Excellent	Excellent	Excellent	Excellent
Indication	Acute relief	Yes	No	No	No
Indication	Maintenance	No	Yes	Yes	Yes