Pharmacology of asthma Flashcards
What drugs are used to treat asthma?
- Salbutamol
- Fluticasone
- Mometasone
- Budesonide
- Montelukast
What is the target of salbutamol?
Beta 2 (β2) adrenergic receptor
What is the primary mechanism of action for salbutamol?
Agonist at the β2 receptor on airway smooth muscle cells. Activation reduces Ca2+ entry and this prevents smooth muscle contraction.
What are the main side effects of salbutamol?
Palpitations/ agitation
Tachycardia/ Arrythmias
Hypokalaemia (at higher doses)
What type of beta agonist is salbutamol?
Short acting (half-life is 2.5 hours)
How does salbutamol cause hypokalaemia?
Hypokalaemia can be caused via an effect on sodium/ potassium ATPase. This effect can be exacerbated by coadministration with corticosteroids
What is the drug target of fluticasone?
Glucocorticoid receptor
What is the primary mechanism of action of fluticasone?
Fluticasone directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.
What are the main side effects of fluticasone?
Local side effects:
Sore throat, hoarse voice, opportunistic oral infections
Systemic side effects: Growth retardation in children Hyperglycaemia Decreased bone mineral density Immunosuppression Effects on mood
How is fluticasone administered?
Oral bioavailability <1%. Therefore, any systemic delivery via the inhaled route is predominantly through the pulmonary vasculature.
What is the drug target for mometasone?
Glucocorticoid receptor
What is the primary mechanism of action of mometasone?
Mometasone directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.
What are the side effects of mometasone?
Local side effects:
Sore throat, hoarse voice, opportunistic oral infections
Systemic side effects: Growth retardation in children Hyperglycaemia Decreased bone mineral density Immunosuppression Effects on mood
How is mometasone administered?
Oral bioavailability <1%. Therefore, any systemic delivery via the inhaled route is predominantly through the pulmonary vasculature
What is the drug target of budesonide?
Glucocorticoid receptor
What is the primary mechanism of action for budesonide?
Budesonide directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.
What are the side effects of budesonide?
Local side effects:
Hoarse voice, opportunistic oral infections
Systemic side effects: Growth retardation in children Hyperglycaemia Decreased bone mineral density Immunosuppression Effects on mood
How is budesonide administered?
Oral bioavailability >10%. Therefore, inhaled budesonide will still result in some systemic absorption through the gastro-intestinal tract.
Less potent than fluticasone and mometasone
What is the drug target of montelukast?
CysLT1 leukotriene receptor
What is the primary mechanism of action of montelukast?
Antagonism of CysLT1 leukotriene receptor on eosinophils, mast cells and airway smooth muscle cells decreases eosinophil migration, broncho-constriction and inflammation induced oedema
What are the side effects of montelukast?
Mild side effects: Diarrhoea Fever Headaches Nausea or vomiting
Serious side effects:
Mood changes
Anaphylaxis
What is the half life of salbutamol?
It’s half life is 2.5-5hours.
Does salbutamol have absolute selectivity?
No
- Cardiac (beta 1) effects can be seen
- Hypokalaemia can be caused via an effect on sodium/ potassium ATPase. (Can be exacerbated by coadministration with corticosteroids)
What is fluticasones affinity for the glucorticoid receptor like compared to cortisol?
Greater affinity
Also for mometasone
What is the potency of budesonide compared to momentasone and fluticasone?
Less potent
How can montelukast be used in regards to exercise?
For prophylaxis of exercise-induced bronchoconstriction, montelukast should be administered at least 2 hours before initiating exercise
