Session 9: Respiratory Pharmacology Flashcards
What is asthma?
A chronic inflammatory airway disease with intermittent airway obstruction and hyper-reactivity of the small airways.
It is reversible both spontaneously and with drugs.
Aims of asthma control.
Minimal symptoms during both night and day.
Minimal need for medication
No exacerbations
No limitation of physical activity
Keep normal lung function
What should be checked before deciding to step up or step down medication of asthma?
Adherence
Inhaler technique
Eliminate trigger factors
Give examples of inhaled corticosteroids (ICS).
Beclometasone
Budesonide
Fluticasone
When are ICS used?
They are a regular preventer when reliever (SABA) is not sufficient on its own.
Briefly explain mechanism of ICS.
Pass through plasma membrane and activate cytoplasmic receptors.
The activated receptor then passes into the nucleus to modify transcription.
Action of ICS.
Reduces mucosal inflammation
Widens the airways
Reduces mucus production
Also reduces symptoms, exacerbations and prevents death.
ADRs of ICS.
Immunosuppressive action locally leading to candidiasis or hoarse voice.
Also a risk of pneumonia in COPD.
How are ADRs reduced in ICS?
If taken correctly
Pharmacokinetics of ICS.
It has a poor oral bioavailability but a lipophilic side chain is added.
There is slow dissolution in aqueous bronchial fluid and a high affinity for glucocorticoid receptors.
ICS are inhaled as the name suggest.
Why are they not taken orally?
Because they are transported from the stomach to the liver by the hepatic portal system but as they reach the liver they will almost complete first pass metabolism meaning none will end up in the systemic circulation.
ADRs of high doses of ICS.
Potential to produce systemic side effects
Give examples of types of beta 2 agonists.
SABA
LABA
Action of SABA.
Symptom relief through reversal of bronchoconstriction and are only used when needed.
When are LABAs used?
As an add on therapy to ICS and p.r.n. (when needed) SABA.
(When it’s not enough anymore)
Action of LABA.
Reversal of bronchoconstriction and also increase mucus clearance by action of cilia.
Give examples of SABAs.
Salbutamol
Terbutaline
Fast and short acting
Give examples of LABAs.
Fast and long acting - Formoterol (12h)
Slow and long acting - Salmeterol (12h), Vilanterol (24h)
Beta 2 - agonist ADRs.
Adrenergic fight or flight effects like tachycardia, palpitations, anxiety and tremors.
Can lead to SVT by higher activity of SAN, increased HR and decreased refractory period at AVN.
Also increased glycogenolysis and increased renin.
Muscle cramps.
Can LABAs be given on their own?
No. They need to be prescribed alongside of ICS because there is an increased risk of death when prescribed alone.
What may reduce the effects of b2 agonists.
Beta blockers
Difference between formoterol and salmeterol.
Formoterol is more potent and efficacious.
Why is LABA always given with ICS?
Because on its own it can mask airway inflammation and cause near-fatal or fatal attacks.
In order to prevent LABAs from being taken alone, what is done?
Combined inhaler.
Pros of a combined inhaler.
Ease of use
Adherence
Less prescriptions
But most of all safety
When LABAs + ICS + SABAs are not enough anymore, what are the next steps?
Increase ICS to medium dose.
LTRA (Leukotriene receptor antagonist)