For an adult with asthma or COPD, should I use salbutamol (albuterol) or levosalbutamol (levalbuterol) as rescue therapy, and how do their doses and side‑effect profiles differ?

Salbutamol vs Levosalbutamol for Asthma and COPD

Use standard salbutamol (albuterol) as your first-line short-acting beta-agonist for rescue therapy in both asthma and COPD, as it is clinically equivalent to levosalbutamol, costs less, and is the only agent validated for continuous nebulization in severe exacerbations. 1, 2

Clinical Equivalence and Dosing

Both medications are clinically interchangeable with equivalent efficacy and safety profiles when dosed appropriately. 1

• Levosalbutamol requires half the milligram dose of salbutamol to achieve comparable bronchodilation 2, 3

  • Salbutamol: 2.5–5 mg nebulized or 2 puffs (200 mcg/puff) via MDI 1
  • Levosalbutamol: 1.25–2.5 mg nebulized or 1 puff (45 mcg/puff) via MDI 1, 3

• Standard dosing for acute exacerbations: 2

  • Salbutamol 2.5–5 mg nebulized every 20 minutes × 3 doses, then every 1–4 hours as needed
  • Levosalbutamol 1.25–2.5 mg nebulized every 20 minutes × 3 doses, then every 1–4 hours as needed

• Onset of action is 5 minutes or less for both agents, peaking at 30–60 minutes, with duration of 4–6 hours 1, 3

Side Effect Profiles

The side effect profiles are essentially identical between the two drugs at equipotent doses. 1

• Common dose-dependent effects include tremor, anxiety, tachycardia, hypokalemia, headache, and hyperglycemia 1
• Levosalbutamol does NOT offer clinically meaningful reduction in side effects despite theoretical advantages 1
• The inhaled route causes minimal systemic adverse effects for both medications 1

Critical Limitation of Levosalbutamol

Levosalbutamol has never been studied for continuous nebulization, which is essential for life-threatening exacerbations. 2

• For severe status asthmaticus or acute COPD requiring continuous therapy (10–15 mg/hour), only salbutamol has guideline support and safety data 2
• This represents a major clinical gap that makes salbutamol the safer choice in emergency settings where escalation may be needed

Cost Considerations

Levosalbutamol costs approximately 35% more than salbutamol ($54 vs $40–55 per inhaler) without demonstrable clinical benefit. 1

• Guidelines recommend choosing based on availability and cost since they are clinically equivalent 2
• The theoretical benefits of removing the S-enantiomer have not translated to meaningful clinical advantages in well-designed trials 1, 4

Practical Treatment Algorithm

For routine rescue therapy:

• Use salbutamol 2 puffs (200 mcg each) via MDI with spacer every 4–6 hours as needed 1
• MDI with spacer is equally effective as nebulizer when proper technique is used 1, 2

For acute exacerbations (asthma or COPD):

• Salbutamol 2.5–5 mg nebulized every 20 minutes × 3 doses 2
• Add ipratropium 0.5 mg to the first 3 doses in acute asthma only (provides modest additional benefit) 1, 2
• Do NOT add ipratropium in acute COPD exacerbations (no proven benefit) 2

For severe/life-threatening exacerbations:

• If inadequate response after 3 doses, initiate continuous salbutamol nebulization at 10–15 mg/hour 2
• Do NOT use levosalbutamol for continuous nebulization (no safety or efficacy data) 2

Common Pitfalls to Avoid

Underestimating MDI equivalence to nebulizers: Six to 10 puffs from an MDI with spacer equals one nebulizer treatment when technique is proper—two puffs are NOT equivalent 1

Overusing short-acting beta-agonists: Use exceeding 2 days per week (excluding exercise prophylaxis) indicates poor asthma control and need for controller therapy escalation 1

Regular scheduled dosing: Regular use (≥4 times daily) reduces duration of action without improving potency—use only as needed 1

Assuming levosalbutamol is "safer": Despite theoretical concerns about S-albuterol, well-designed clinical studies have failed to demonstrate significant toxicity, and the clinical superiority of levosalbutamol remains marginal at best 4, 5