Bronchodilators Flashcards
How can respiratory disease close airways (3 points)
Narrowing of airways due to inflammation and swelling.
Constriction of muscles around airways.
Increased production of sticky mucus.
What are two relievers as bronchodilators?
Acts on autonomic nervous system.
Short-acting Beta-2 agonists.
Muscarinic antagonists.
(Fast onset)
What are three controllers as bronchodilators?
Acts on autonomic nervous system.
Long-acting Beta-2 agonists.
Methylxanthines.
Leukotriene receptor antagonists.
(Slow onset)
Sympathetic nerves innervate bronchioles and Beta-2 receptors are present here. What does sympathetic stimulation cause?
Relaxes the muscles - bronchioles/airways open up.
Parasympathetic nerves innervate the bronchus and bronchioles and muscarinic (M3) receptors are present here. What does parasympathetic stimulation cause?
Constricts the muscles - bronchioles/airways close.
What class of receptor is B2 receptors?
G-Protein Coupled Receptors.
What class of receptor is M3 receptors?
G-Protein Coupled Receptors.
Name 4 types of bronchodilators in general.
Beta-2 agonists.
Muscarinic antagonists.
Methylxanthines.
Leukotriene receptor antagonists.
What are short acting inhalers called?
Relievers
What are long acting inhalers called?
Controllers/Preventers
What do B2-adrenergic agonists do?
Stimulate B2 receptors preferentially.
Cause relaxation of smooth muscles in bronchioles.
What are short acting inhalers used for?
These are reliever inhalers, used for occasional relief of symptoms - asthma attacks.
What are long acting inhalers used for?
These are controller inhalers, used for controlling chronic symptoms - COPD.
How are B2 adrenergic agonists delivered and why?
Via aerosolising inhalers.
Minimise adverse effects. Administered via mouth - reaches lungs - immediate access to site of action.
Give two examples of SABAs and the duration.
Salbutamol
Terbutaline
Fast onset. Duration: 4 hours
Give two examples of LABAs and the duration.
Formoterol
Salmeterol
Slow onset. Duration: 8-12 hours
Why can’t salmeterol be given to treat asthma attack?
It is slow acting. Attack needs a SABA.
Sometimes LABAs are given with steroids. Why might this be?
Steroids deal with inflammatory effects.
Salmeterol deals with constriction of airways.
How does muscarinic antagonist work as bronchodilators?
Block action of Ach on M3 muscarinic receptors and cause relaxation of smooth muscle.
What kind of substrate is the bronchodilator which blocks M3 receptors?
Competitive anatgonist.
Muscarinic antagonists are used as bronchodilators. Name 3 examples of inhalers used?
All are short acting: Ipratropium bromide (Atrovent) Oxitropium (Oxivent) Tiotropium bromide (Tiova)
Methylxanthines have two mechanisms of action. What are they?
Acts as bronchodilator.
Acts as anti-inflammatory.
How does methylxanthines act as bronchodilators?
Acts as a competitive inhibitor of phosphodiesterase - results in raised intracellular cAMP and PKA activation.
How do methylxanthines act as anti-inflammatory agents?
Inhibits TNF-alpha and blocks leukotriene synthesis - dampens and relieves the inflammation.
What is the main methyxanthine used in the treatment of asthma and COPD?
Theophylline.
How is theophyline administered?
Administered orally as tablets - not effective through inhalation.
Available in immediate and sustained release formulations.
Why is theophylline not used as first line medication?
Due to narrow therapeutic window.
Can have serious side effects.
Used as last resort in hospital so patient can be monitored.
How are leukotrienes produced?
Produced by the oxidation of arachidonic acid by the lipoxygenase pathway. Arachidonate 5-lipoxygenase catalyzes this reaction.
What is the effect of leukotriene release in asthma?
Causes bronchoconstriction and contributes to inflammation.
What are leukotriene receptor antagonists used as?
As preventer drugs.
Describe leukotriene receptor antagonist MOA.
Block action of leukotrienes on receptors.
Causes bronchodilation, relaxes airways.
Dampen inflammation.
Relieve symptoms.
Give an example of a leukotriene receptor antagonist drug.
Montelukast.
Zafirlukast.
Pranlukast.
