Clinical pharmacology Flashcards
Name some short acting ß2 agonists
- Salbutamol
- Terbutaline
What is the mechanism of action of ß2 agonists?
β2 agonists work by mimicking the effect of norepinephrine on β2 receptors. This produces sympathetic effects on tissues containing β2 receptors; in this case bronchodilation of the airways
What are the adverse effects of inhaled SABA?
Dose delivered by inhalation rarely causes adverse effects, however, can cause:
- Tacyrrhytmias - B1 activation in cardiac tissue
- Hyperglycaemia - only an issue in diabetic patients).
- Fine tremor - B2 receptors in skeletal muscle
- Hypokalaemia - β2 agonists cause a shift of ions into the cell
- Paradoxical bronchospasm - rare
What are examples of long-acting ß2 agonists?
- Salmeterol
- Formoterol
What are examples of inhaled corticosteroids?
- Beclamethasone
- Budesonide (400 Microgram)
- Fluticasone (200 Microgram)
- Ciclosonide (200-300 Microgram)
- Momentasone (200 Microgram)
What are corticosteroids used for in asthma?
Used as a preventer
What is the mechanism of action of corticosteroids when used to treat asthma?
Corticosteroids act to reduce inflammation in the airways:
- Decrease neutrophil and macrophage recruitment and action
- Decrease fibroblast formation
- Decrease production of prostanoids
- Decrease production of cytokines
- Decrease histamine release
- Decrease IgG production
This reduces oedema and mucus production in the airways as well as inhibiting allergic reactions.
What are the side effects of corticosteroids?
- Osteoporosis
- Cataract
- Acute Glaucoma
- Cushingoid features including weight gain
- Increased susceptibility to infection
- Hyperglycaemia
- Hypertension
- Fluid retention and worsening of heart failure
- Hypokalaemia
- Mental disturbance including psychosis
- Addisonian crisis in abrupt withdrawal
How do leukotriene receptor antagonists work?
The leukotriene receptor antagonists block the effects of leukotrienes at the LTC4, LTD4 and LTE4 receptors in the airways, decreasing both the early and late responses to inhaled allergens.
What are examples of leukotriene receptor antagonists?
- Monteukast
- Zafirlukast
What is the action of xanthines?
Administration of xanthines results in dilatation of the airways and is a useful drug in the treatment of airway obstruction (especially asthma). There is also evidence to suggest that xanthines have anti-inflammatory / immunomodulatory and broncho-protective effects that are mediated by other molecular mechanisms.
What types of asthma are leukotriene receptor antagonists most effective against?
- Exercise induced asthma
- Aspirin induced asthma
What are side effects to leukotriene receptor antagonists?
Common
- Headache
- Gastrointestinal disturbances
Rare
- Churg-Strauss syndrome
- Agranulocytosis
What are examples of xanthine medications?
- Theophylline
- Aminophylline
How do antimuscarinic agents work?
Muscarinic antagoinists competitively inhibit cholinergic receptors on bronchial smooth muscle. They block the action of acetylcholine on the nerve endings therefore inhibiting the parasympathetic effect. This results in dilatation of the airways.
