Respiratory Pharmacology: Bronchodilators

Which receptor type is primarily stimulated by sympathetic bronchodilators?

What is the main action of parasympathetic bronchodilators in the airways?

A patient requires immediate relief from acute bronchospasm. Which type of medication would be most appropriate?

Which of the following is a common side effect associated with sympathetic bronchodilators, but not parasympathetic bronchodilators?

How long do long-acting anticholinergics typically last?

Which of the following best explains the mechanism of action of SABAs?

A patient is prescribed a bronchodilator and experiences a dry mouth. Which type of bronchodilator is most likely causing this side effect?

Which medication is an example of a LABA (long acting beta agonist)?

Sympathetic Bronchodilators (Beta-agonists)

Mechanism: Stimulate beta-2 adrenergic receptors in airway smooth muscle, causing relaxation and bronchodilation.
Types:
- Short-acting beta-agonists (SABAs): Quick relief; examples include albuterol and levalbuterol.
- Long-acting beta-agonists (LABAs): Long-term control and prevention; examples include salmeterol and formoterol.
Onset and Duration:
- SABAs: Rapid onset (minutes) and short duration (4-6 hours).
- LABAs: Slower onset but longer duration (up to 12 hours or more).
Side Effects: Tachycardia, palpitations, tremors, nervousness (due to beta-1 receptor stimulation).

Parasympathetic Bronchodilators (Anticholinergics)

Mechanism: Block acetylcholine from binding to muscarinic receptors in airway smooth muscle, preventing bronchoconstriction.
Types:
- Short-acting anticholinergics: Quick relief; example is ipratropium.
- Long-acting anticholinergics: Maintenance treatment; examples include tiotropium and umeclidinium.
Clinical Use: Acute relief (SABAs) or maintenance therapy (LABAs and long-acting anticholinergics, particularly in chronic conditions like COPD).

Comparison of Bronchodilators

Mechanism Differences: Sympathetic bronchodilators directly stimulate beta-2 receptors, while parasympathetic bronchodilators block acetylcholine.
Onset and Duration: Sympathetic bronchodilators (especially SABAs) act quickly, while parasympathetic bronchodilators have a slower onset but longer duration.
Side Effect Profiles: Sympathetic bronchodilators can cause cardiovascular side effects, while parasympathetic bronchodilators primarily cause localized effects like dry mouth.

This quiz covers the mechanisms, types, and effects of sympathetic and parasympathetic bronchodilators. It includes information on short-acting and long-acting beta-agonists and anticholinergics, their onset, duration, and side effects. Test your understanding of these essential medications in respiratory therapy.