pharmacology of asthma Flashcards
primary mechanism of action of salbutamol
agonist at b2 receptor on airway smooth muscle cells. activation reduces ca2+ entry preventing smooth muscle contractions
what is the target of salbutamol
beta 2 adrenergic receptor
what are the main side effects of salbutamol
palpitations agitation tachycardia/ arrythmias hypokalaemia - at higher doses
extra info on salbutamol
= short acting beta agonist
half like is 2.5-5 hrs
beta 2 selectivity is not absolute - cardiac (beta1) effects cen be seen
how is hypokalaemia a side effect of high dose salbutamol
caused via effect on sodium/potassium atpase. effect can be exacerbated by coadministration with corticosteroids
mechanism of fluticasone
very powerful drug!
multiple actions on multiple cells
directly decreases inflammatory cells e.g eosinophils, monocytes, macrophages and dendritic cells. reduces the number of these cells and number of cytokines they produce
target of fluticasone
glucocorticoid receptors
what are the local side effects of fluticasone
sore throat, hoarse voice, opportunistic oral infections
what are the systemic side effects of fluticasone
growth retardation in children hyperglycaemia decreased bone mineral density immunosuppression effects on moods
extra info on fluticasone
greater affinity for glucocorticoid receptor compared to cortisol
oral bioavailability <1%, therefore any systemic delivery via inhaled route is predominantly through pulmonary vasculature
what is mechanism of action of mometasone
very powerful drugs!
multiple actions on many different cells
directly decreases inflammatory cells e.g eosinophils, monocytes, mast cells, macrophages and dendritic cells. reduces number of these cells and number of cytokines they produce
what is the target of mometasone
glucocorticoid receptor
local side effects of mometasone
sore throat, hoarse voice, opportunistic oral infections
systemic side effects of mometasone
growth retardation in children hyperglycaemia decreased bone mineral density immunosuppression effects on mood many others
what is mechanism of action of budesonide
very powerful drug!
multiple action on different cell types. directly decreases inflammatory cells e.g eosinophils, monocytes, mast cells, macrophages and dendritic cells. reduces number of cells and also number of cytokines they produce
target of budesonide
glucocorticoid receptor
local side effects of budesonide
hoarse voice
opportunistic oral infections
systemic side effects of budesonide
growth retardation in children hyperglycaemia decreased bone mineral density immunosuppression effects on mood many others
extra info on budesonide
oral bioavailability >10%
therefore inhaled budesonide will still result in some systemic absorption through gi tract
less potent than fluticasone and mometasone
mechanism of action of montelukast
antagonism of cysLT1 leukotriene receptor on eosinophils, mast cells and airway smooth muscle cells.
decreases eosinophil migration, bronchoconstriction and inflammation induced oedema
target of montelukast
cysLT1 leukotriene receptor
mild side effects of montelukast
diarrhoea
fever
headaches
nausea/vomiting
serious side effects of montelukast
mood changes
anaphylaxis
extra info on montelukast regarding prophylaxis of exercise induced bronchoconstriction
should be administered at least 2 hrs before initiating exercise
bnf guidelines for salbutamol use in children
by inhalation:
child - 100-200micrograms, upto 4 times a day for persistent symptoms
by mouth:
for child 1 month-1yr - 100 micrograms/kg 3-4 times a day
2-5yrs - 1-2mg 3-4 times a day
what % of the inhaled dose of salbutamol penetrates deep enough into lungs to be able to influence lung function
20%
