Metaproterenol (Orceprenaline) Use in Asthma and COPD
Metaproterenol is a short-acting β2-agonist that should be used only for acute symptom relief ("as needed") in asthma and COPD, not as maintenance therapy, and has been largely superseded by more selective agents like salbutamol with better side effect profiles. 1
Current Role in Clinical Practice
For Asthma
- Use metaproterenol only for acute breakthrough symptoms, not as scheduled maintenance therapy 1, 2
- Inhaled aerosol delivery (metered-dose inhaler) is strongly preferred over oral formulations due to superior efficacy and minimal side effects 2
- Aerosol metaproterenol produces bronchodilation within 30 seconds with duration of 3-4 hours 3
- Sequential inhalation technique (multiple puffs spaced 20 minutes apart) provides optimal bronchodilation without significant adverse effects 2
For COPD
- In stable COPD, metaproterenol should only be used "as required" for acute symptom relief, not as regular maintenance therapy 1
- For symptomatic patients with FEV1 <60% predicted, long-acting bronchodilators (long-acting β-agonists or anticholinergics) are strongly recommended as first-line maintenance therapy instead 1
- For mild COPD with intermittent symptoms, short-acting bronchodilators like metaproterenol may be used as needed 1
Delivery Method Algorithm
Step 1: Always attempt metered-dose inhaler (MDI) first 1
- MDI with proper technique is equally effective as nebulizer therapy and significantly cheaper 4
- Doses up to 1 mg salbutamol equivalent (approximately 3 puffs of metaproterenol) should be delivered via MDI 1
Step 2: Consider spacer device if technique is suboptimal 1
- Optimize inhaler technique before escalating to nebulizer therapy 1
Step 3: Nebulizer therapy only if MDI fails or very high doses needed 1
- Nebulized metaproterenol 15 mg provides equivalent bronchodilation to 1.95 mg via MDI (3 puffs) in both asthma and COPD 4
- Nebulizers should only be prescribed after formal assessment by a respiratory physician 1
Comparative Efficacy
Versus Other Bronchodilators
- In COPD, ipratropium bromide (anticholinergic) demonstrates superior peak bronchodilation and longer duration compared to metaproterenol 5
- Terbutaline shows earlier peak activity and longer duration than metaproterenol, especially on large airways 3
- Modern selective β2-agonists (salbutamol, terbutaline) are preferred over metaproterenol due to better selectivity and duration 3
Combination Therapy
- Combining inhaled and oral metaproterenol produces greater bronchodilation than either alone, but oral formulations cause significant side effects 6
- Avoid oral metaproterenol due to tremor, palpitations, tachycardia, and increased systolic blood pressure, particularly in older patients 2, 6
Critical Pitfalls to Avoid
Do not use metaproterenol as monotherapy maintenance in asthma or COPD 1
- This is outdated practice; guidelines mandate long-acting bronchodilators for maintenance 1
Do not prescribe oral metaproterenol when inhaled formulations are available 2, 6
Do not assume nebulizer therapy is superior to MDI 4
- Both deliver equivalent bronchodilation when MDI technique is proper 4
- Nebulizers are more expensive and less convenient 4
Ensure proper inhaler technique before changing devices or medications 1
- 76% of COPD patients make critical errors with MDI technique 1
- Demonstrate and re-check technique at every visit 1
Practical Dosing
Inhaled (MDI)
- 2-3 puffs (0.65 mg per puff) as needed for acute symptoms 4, 2
- May repeat every 4-6 hours based on symptom control 3
Nebulized (if MDI inadequate)
- 15 mg in 2.3 mL solution for acute exacerbations 4
- Equivalent efficacy to 3 puffs MDI but less convenient 4
Modern Context
Metaproterenol has been largely replaced by more selective β2-agonists (salbutamol/albuterol, terbutaline) in contemporary practice 3