Asthma and COPD Flashcards
What does SABA stand for?
Short acting beta-2 agonists
What does LABA stand for?
Long acting beta-2 agonists
What does SAMA stand for?
Short acting muscarinic antagonist
What does LAMA stand for?
Long acting muscarinic antagonist
What does LTRA stand for?
Leukotriene receptor antagonists
What is an example of a SABA?
Salbutamol
Terbutamine
What is an example of a LABA?
Salmeterol
Formoterol
What is an example of a SAMA?
Ipratropium
What is an example of a LAMA?
Tiotropium
What is an example of a LTRA?
Montelukast
What is the common brand name of salbutamol?
Ventolin
How long does it take SABAs to have a maximum effect and what is the duration of action?
Maximum effect within 30 minutes
Duration of action is 4-6 hours
What is the duration of action of LABAs?
12-24 hours
What is special about formoterol?
It has a dual action, meaning it has both short and long acting effects. Is used in MART therapy- maintenance and reliever therapy
What are the 3 LABAs that are only licensed for the treatment of COPD (can’t be used in asthma)?
Indacaterol
Olodaterol
Vilanterol
What may be used if a patient is having a severe asthma attack?
An IV form of salbutamol or terbutaline
What are the adverse effects of SABAs and LABAs if they reach systemic circulation?
- Tremors
- nervous tension
- headache
- tachycardia/palpitations
- hyporkalaemia
What factors increase the risk of adverse effects from beta 2 agonists?
- Taken as a IV or oral form- more likely to reach systemic circulation ( try to void)
- large doses
- Using the reliever inhales frequently during acute exacerbation
What causes the tremor sometimes caused by short acting beta-2 agonists?
Direct stimulation of beta-2 receptors in skeletal muscle. Often in hands and quick onset
What causes tachycardia sometimes caused by short acting beta-2 agonists?
The agonistic effects of beta-1 receptors on the heart.
Very disturbing for patients
What causes hypokalaemia sometimes caused by short acting beta-2 agonists and what patients are at risk?
Caused by increased cellular potassium uptake.
Those already taking medications such as diuretics, xanthines and steroids
Why is it important to take care when prescribing beta-2 agonists in those with cardiovascular problems?
Those with cardiovascular diseases are often taking beta-blockers which are beta antagonists (e.g. atenolol or propranolol) so would disrupt the action of these beta 2 agonist medications. These drugs are taking for action of b1 receptors on the hearts to slow heart rate however we need to ensure beta agonists are cardio-selective.
What are SABA used as?
Rescue or reliever therapies
SABA counselling points
carry at all times
may take before triggers e.g. before excercise
If being used very frequently (more than 3 times a week), it signifies a poorly controlled condition and should be referred.
What are LABA used as?
Preventer therapies- usually taken twice a day
What does MART therapy contain?
Formoterol + a steroid
What is MART therapies used as?
Usually taken twice a day as a preventer therapy but should be carried also to use as a reliever. Only in asthma
What type of receptor are the beta-2 receptors?
G-protein coupled receptor (GPCR)
What type of receptor are the beta-2 receptors?
G-protein coupled receptor (GPCR)
How do Beta-2 agonists work?
Bind to the beta-2 adrenoreceptors ( 7 transmembrane- domain GPCR) on airway smooth muscle cells. This binding induces a conformational change in the g alpha s subunit and it dissociates from the beta-gamma. It then binds to and activates adenyl cyclase to catalyse the conversion of ATP to cAMP. cAMP then activates protein kinase A. PKA and cAMP inhibits the release of calcium ions from intracellular stores. The decrease in calcium ions prevents smooth muscle contraction as it inactivates myosin light chain kinase from being able to perform the power stoke needed for muscle contraction. Normally ca2+ would bind to calmodulin to form a complex that activates MLCK to phosphorylate myosin light chain and form a cross-bridge with actin to cause muscle contraction. But as MLCK has been inactivates, this contraction cannot occur.
Aside from the most obvious action of beta-2 agonists, how else can they have an effect?
- Reduce mediator release from mast cells
- Reduce plasma exudation
- Reduce cholinergic transmission
- Increases mucus clearance
- Increase in pulmonary surfactant
Why is monotherapy with just a LABA or SABA strongly discouraged?
Because once the agonist has bound, the GPCRs on the immune cells (eosinophils, neutrophils, t-cells) can be quickly desensitised meaning no prolonged anti-inflammatory effects. Hence why not used as a monotherapy. Has been linked with increased hospitalisation, poorly controlled asthma and deaths. Now usually use a low dose of an inhaled corticosteroid as a first step.
Why is monotherapy with just a LABA or SABA strongly discouraged?
Because once the agonist has bound, the GPCRs on the immune cells (eosinophils, neutrophils, t-cells) can be quickly desensitised meaning no prolonged anti-inflammatory effects. Hence why not used as a monotherapy. Has been linked with increased hospitalisation, poorly controlled asthma and deaths. Now usually use a low dose of an inhaled corticosteroid as a first step.
What are some examples of inhaled corticosteroids used in asthma?
- Beclometasone
- Budosonide
- Fluticasone