Bronchodilators: beta-2 agonists, muscarinic antagonists and theophylline
How beta-2 agonists, muscarinic antagonists and methylxanthines relax airway smooth muscle, how onset and duration explain their roles in asthma and COPD, why SABA-only asthma treatment is unsafe, and the adverse effects and theophylline kinetics that Paper 1 examines.
Tier 1Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Bronchodilators relax airway smooth muscle by raising cAMP (beta-2 agonists, theophylline) or blocking acetylcholine at M3 receptors (muscarinic antagonists).
- They relieve bronchospasm but do not treat eosinophilic airway inflammation. In asthma, regular or SABA-only beta-agonist use without an ICS raises the risk of severe exacerbation and death.
- The Australian Asthma Handbook (V3.0, 2025) recommends an anti-inflammatory reliever (budesonide-formoterol) over SABA for adults and adolescents.
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Sources
- Australian Asthma Handbook, version 3.0AU/NZNational Asthma Council Australia, 2025 (V3.0)
- COPD-X Plan: Australian and New Zealand Guidelines for the management of Chronic Obstructive Pulmonary Disease, version 2.78AU/NZLung Foundation Australia and Thoracic Society of Australia and New Zealand, 2.78 (December 2025)
- Global Strategy for Asthma Management and PreventionGlobal Initiative for Asthma, 2026
- Therapeutic Guidelines: RespiratoryAU/NZTherapeutic Guidelines Limited, current eTG edition
- Rang & Dale's Pharmacology (10th ed.)Elsevier (Ritter et al., 2023), 2023
- Last updated
- 14 November 2026
What changed
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