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acetylcholine esterase inhibitor
- edrophonium (SA), neostigmine (LA)
- organophosphates which phosphorylate the acetylcholine esterase enzyme preventing its breakdown, increasing [ACh] in synaptic junction and therefore increasing the EPSP
- myasthenia gravis (reduced AChRs), antidote for muscle relaxants
- increased parasympathetic activity e.g. GI disturbances, bronchoconstriction. decreased HR
-
muscarinic antagonist
- atropine, ipratropium (bronchodilator with with beta2), scopalamine (motion sickness)
- competitively bind to muscarinic receptors to prevent binding and depolarisation by ACh, decreasing parasympathetic stimulation
- decreased GI motility (constipation), secretion (dry mouth), increased HR (tachycardia, palpitations), urine retention
-
depolarising neuromuscular blockers
- succinylcholine
- binds to free closed NMJ nicotinic receptor causing a depolarision but desensitising the receptor to ACh even after repolarisation to prevent further depolarisation by ACh binding, decreasing muslce contraction
- muscle relaxant pre-op
- may bind to M receptors as agonist causing parasympathetic disturbances (increased GI secretions, motility; bradycardia), muscle pains, hyperkalemia due to excessive contraction at administration
-
non-depolarising neuromuscular blocker
- tubocurarine
- binds to NMJ nicotinic receptor preventing binding and depolarisation by ACh preventing muscle contraction
- adjuvant to surgical anaesthesia
- histamine release causes hypotension and bronchospasm
-
norepinephrine
- nonspecific adrenergic agonist which binds to activates both alpha and beta adrenergic receptors
- however lower affinity for beta 2 meaning its alpha 1 effects are magnified causing vasoconstriction, HTN and reflex bradycardia
- used for severe hypotension, septic shock
-
epinephrine
- nonspecific adrenergic agonist which binds to activate both alpha and beta adrenergic receptors
- increases HR and decreases BP at low dose, cause HTN at high dose
- used for cardiogenic shock, cardiac arrest
-
alpha 1 specific agonist example and indication
- phenylephrine
- nasal decongestant
-
alpha 2 specific agonist (-ADRs)
- clonidine, alpha methyldopa
- activate alpha 2 receptors which act in negative feedback, decreasing sympathetic stimulation, therefore actually acting to decrease adrenergic nerve stimulation overall
- antihypertensive
-
beta 1 specific agonist (-ADRs)
- dobutamine
- increase HR and SV
- heart failure, cardiogenic shock
-
beta 2 specific agonist
- salbutomal, salmeterol (+ fluticasone)
- increase bronchodilatory action of beta 2 receptors in respiratory SM
- asthma
- hypotension with reflex tachycardia, skeletal tremors and hypokalemia (futher increasing HR)
-
alpha adrenergic blockers
- prazosin, doxazosin
- block alpha 1 adrenergic receptors which normally cause vasoconstriction, causing vasodilation and reducing BP
- antihypertensive
- few side effects due to specificity
-
beta adrenergic blockers
- propanolol (nonselective), metoprolol/atenolol (beta 1 seelctive), carvedilol (beta 1 and 2, alpha 1)
- block beta 1 and 2 (cause bronchoconstriction as a side effect) adrenergic receptors which normally increase HR/SV, while extra blockade of carvedilol also causes vasodilation for antihypertensive
- used for range of CVS diseases
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