pharmacology of the airways Flashcards
what is asthma?
episodes where airflow is limited (can be spontaneous or in response to stimuli).
what is a key characteristic of asthma?
reversibility
what causes airflow to become limited in asthma?
spams in bronchial muscle, oedema and mucus plugging
what is hyper-sensitivity?
normal response to very low levels of stimulus
what is hyper-reactivity?
exaggerated response to a stimulus
how does a low level stimulus affect someone with asthma?
triggers an exaggerated response
what is the immune mechanism of someone with asthma?
antigens cross link with IgE on mast cells –> histamine release and cytokine release (IL-3 and IL-4)
Immature CD4+ –> Th2 lymphocytes
release more cytokines and recruit inflammatory cells
B cells –> IgE producing plasma cells –> more response
leads to inflammatory response, bronchoconstriction, oedema and mucus production
what drugs trigger asthma and how?
beta blockers - blocks beta 2 receptor which mediates bronchodilation
cyclooxyrgenase (COX) blockers - increase arachidonic acid which causes leukotriene production
what is the asthma treatment ladder?
Step 1 = inhaled short acting beta 2 agonists
Step 2 = add inhaled steroid
Step 3 = add inhaled long-lasting beta 2 agonist (LABA)
Step 4 = further increase steroid, add fourth drug (e.g. leukotriene receptor antagonist)
Step 5 = use daily steroid tablet
what types of bronchodilators are there?
beta agonists - long and short acting
anti-cholinergic/muscarinic
Phosphodiesterase inhibitors
how do beta agonist bronchodilators work?
mimic sympathetic nervous system
what is salbutamol?
short acting beta agonist bronchodilator
what is salmeterol?
long acting beta agonist bronchodilator
how do anti-cholinergic/muscarinic bronchodilators work?
block parasympathetic impact of bronchoconstriction
how do phosphodiesterase inhibitors (PDE)?
prolong cAMP
