9.2 Respiratory Pharmacology Flashcards
what is asthma?
A Chronic inflammatory airway disease resulting in intermittent airway obstruction and hyper-reactivity. Primarily affects the small airways. Reversible both spontaneously and with drugs. a heterogeneous disease
Asthma is described as a heterogenous disease. What does this mean?
has both genetical and environment factors that influence its development
what evidence of asthma can be seen microscopically?
more eosinophils due to inflammatory nature
more macrophages and T cells
what are some of the macroscopic evidence of asthma?
tightening of smooth muscles in the airways
mucosal oedema
mucus plugging
what are the aims of asthma treatment?
- Minimal symptoms during the day and night
- Minimal need for reliever medication
- No exacerbations
- No limitation of physical activity
- Normal lung function (FEV1 and/or PEF >80% predicted or best)
- Aim is for early control with stepping up OR down as required
before adjusting asthma doses, what should be considered?
adherence
inhaler technique
eliminate/reduce trigger factors
what is uncontrolled asthma?
asthma that impacts a person’s lifestyle or restricts their usual activities
defined as:
- 3 days or more a week with symptoms
- 3 days or more a week with required use of SABA for symptom relief
- 1 or more night a week with awakening due to asthma
what are the symptoms associated with uncontrolled asthma?
coughing
shortness of breath
chest tightness
what are the different stages of pharmacological intervention for asthma?
- Short acting B2 agonist (salbutamol) and low dose ICS
- add inhaler LABA to low dose ICS
- increasing ICS to a medium dose or adding LTRA
- refer patient to specialist care
give some examples of inhaled corticosteroids
beclometasone
budesonide
fluticasone
what is the mechanism of action of inhaled corticosteroids?
Pass through plasma membrane, activate cytoplasmic receptors, activated receptor then passes in to nucleus to modify transcription.
gene activation results in increased number of B2 receptors, increased anti-inflammatory mediators and inhibition of the release of arachidonic acid
Gene repression causes a decrease in the inflammatory mediators interleukins, chemokines and cytokines
what is the action of inhaled corticosteroids?
Reduces mucosal inflammation, widens airways, reduces mucus
Reduces symptoms, exacerbations and prevents death
what are the adverse effects of inhaled corticosteroids?
can cause local immunosuppressive action - candidiasis
horse voice
pneumonia risk possible in COPD at high doses
how are inhaled corticosteroids modified to limit systemic side effects?
lipophilic side chain added
slow dissolution in aqueous bronchial fluid so less enters systemic circulation
give examples of fast short acting beta agonists?
salbutamol
terbutaline
give examples of fast long acting beta agonists?
formoterol
give examples of slow long acting beta agonists?
salmeterol
what is the function of SABAs?
symptom relief through reversal of bronchoconstriction
Used P.r.n. (as required)
what is the function of LABA?
Add on therapy to ICS and p.r.n SABA
what effects of beta agonists help relieve symptoms of asthmatics?
Bronchodilation
Also increase mucus clearance by action of cilia
Prevention of bronchoconstriction prior to exercise (SABA)
what are the adverse affects of Beta agonists?
Adrenergic - fight or flight effects (Tachycardia, palpitations, anxiety and tremor)
Increased Glycogenolysis (liver)
Increased renin (kidney)
SVT – (increased sinoatrial node activity -> increased HR, decreased refractory period at AVN)
why should LABAs only be prescribed alongside ICS?
alone can mask airway inflammation and near-fatal and fatal attacks
CVD – tachycardia may provoke angina