Drugs for Asthma Flashcards
What is the class of first-line bronchodilator drugs for asthma?
Beta-2 adrenoceptor agonists
What is the class of first-line anti-inflammatory drugs for asthma?
Corticosteroids
Name an example of a short-acting inhaled bronchodilator drug.
Salbutamol (5-15 min onset, 4-6 hours duration, SABA)
Name an example of a long-acting inhaled bronchodilator drug that is also fast-acting used as both a controller and reliever for asthma?
Formoterol (2-3 min onset, 12 hours duration, LABA)
Name an example of a long-acting inhaled bronchodilator drug that is slow-acting used for asthma.
Salmeterol (12 h LABA)
Slow-acting so used only as controller NOT reliever
What is the MOST dangerous adverse effect of beta-2 agonists in asthma?
Downregulation of beta-2 receptors results in reduced efficacy of beta-2 agonist-induced bronchodilation when required to relieve acute asthma attack.
The risk of receptor downregulation is greatest with LABAs. LABAs used alone increase the risk of death from asthma.
What must be co-prescribed with LABAs to reduce the risk of downregulation of beta-2 agonists?
A corticosteroid must always be co-prescribed with LABAs for asthma.
The LABAs are formulated in combined inhalers together with corticosteroids to ensure that the two drugs are taken together.
The concern even extends to SABAs if they are over-used. Increasingly for patients ≥12 years-old, salbutamol is being replaced with formoterol+ budesonide inhaler.
Name a SAMA that can be combined as an adjunct with beta-2 agonist to produce greater bronchodilation in asthma?
Ipratropium bromide (SAMA)
List common adverse effects of inhaled muscarinic receptor antagonists.
- Limited systemic side effects as not well absorbed into systemic circulation when taken by inhalation
- Unpleasant taste
- Typical parasympatholytic effects:
- Dry mouth
- Urinary retention (especially in the elderly)
Briefly explain the mechanisms of action of methylxanthines such as theophylline.
- Inhibits phosphodiesterases (PDEs)
- Blocks adenosine receptors
- ↑ Epinephrine release from adrenal medulla
- CNS stimulant action on respiration
- NOT used clinically as an anti-inflammatory but it has some weak anti-inflammatory effects
- Effects on mast cells and T-cells
- ↓ Microvascular leakiness
List adverse effects of methylxanthines such as theophylline.
- Narrow therapeutic window (therapeutic range for theophylline: 5-20 mg/L)
- Many drug-drug interactions: Caution for potential drug interactions
- Gastrointestinal: Nausea, vomiting, abdominal discomfort, anorexia
- CNS: Nervousness, tremor, anxiety, insomnia, seizures
- Cardiovascular: Arrhythmias
Name an example of a soft steroid
Ciclesonide
What is a soft steroid?
An inhaled prodrug that is converted by esterases in the lungs into the active steroid (e.g., ciclesonide).
As the drug is only active in cells expressing esterases adverse effects are minimised even if the drug escapes into the systemic circulation.
List SEVEN more common adverse effects of inhaled corticosteroids.
- Oropharyngeal candidiasis (opportunistic infection due to localised immunosuppression)
- Dysphonia (enfeebled voice due to localised muscle wasting)
- Cough / throat irritation
- Adrenal suppression (e.g. fluticasone)
- Easy bruising (especially in elderly)
- Posterior subcapsular cataracts (especially in elderly)
- Osteoporosis (especially in elderly)
Name an example of a 5-lipoxygenase inhibitor
Zileuton
