Cholinoceptor antagonists Flashcards
What property do both agonist and antagonist share? and which one does only one have?
Affinity-both have it-ability to bind the target/receptor-the more powerful the affinity, the longer it’ll be bound
Efficacy-only Agonist-ability to activate the receptor after binding.
Where are nicotinic receptor found?
Ganglias of SNS and PSNS
And in the adrenal gland
Act on the entirety of ANS
What are ganglion blocking drugs?
Other name of Nicotinic receptor antagonists
BUT not always blocking receptors-can also act on ion channels
What are the 2 nicotinic receptor antagonists we should know?
Hexamethonium (Historical) and Trimetaphan (the one we use)
USE-DEPENDENT block for the ION channel only (more open the channel, the better the drug works)-PSNS/SNS affected depending on which one was active when drug was given
Do nictonic receptor antagonist have affinity?
If they block receptor-yes
But if they are blocking the ion channels (sit in the middle)-No (not called that)
Why do nicotinic receptors antagonist cause hypotension? What are the side effects of each?
At rest-would cause high HR (bad)
But will block constant constriction of blood vessel
And block renin secretion in Kidney
Hexamethonium - theyre actually good hypotensive, but large side effects (like pupils dilation, constipation , bladder, no sweat )
trimetaphan-better, but very short acting-used during surgery and other
What other nictonic receptor antagonist are there?
a-bungatoxin -poison-best antagonist in the world, and fully covalently blocks nicotinic receptors-need tissue to be replaced
Bad cause also acts on CNS
What are 2 exemples of Muscarnic Receptor antagonists?
Atropine and Hyoscine
What are the effects of Atropine and Hyoscine?
Atropine does little to CNS on normal dose (toxic dose bad-restless, agitation)-less M1 selective
Hyoscine-normal dose causes sedation/amnesia. toxic causes paradoxical CNS depression (and VERY high, excitation) (unsure why, but possibly because different brain parts have different receptors/or that hyoscine is more lipid soluble)
What are the 6 main uses of Muscarinic receptor antagonist?
Tropicamide-blocks Musc-dilate pupils and can get a good look at back of eye
Aneathetic premedication (open airways, block saliva/waterysecretion, HR and Contractility down + sedation)
Neurological - motion sickness (hyoscine patch which stops the sensory mismatch causing vomiting (cholinergic nerve))
Parkinsons disease- (lose dopagenrnic neurons, normal are supressed by cholinergic)-Block the inhbition, which is overboard when Dopa neurons already dying)
Asthma, Obstructive disease -more or less same effects of Salbutamol (usually Ipratropium Bromide-keeps it in the more or less in the lungs)
IBS (reduce motility etc-M3 antagonists)
What are the 4 side effect of Muscarinic Receptor antagonists?
Hot as hell, Dry as a bone, Blind as a bat, mad as a hatter
(less sweating, thermoregulation), Less secretions, Cyclopegia, CNS distrubance
What drugs would you give for atropine poisoning?
Bethanechol- too specific
Ecothiopate, Physostigmine -cholinterase blockers
(Eco is irrevesible so use physostigmine)
main physostigmine
What is Botulinium toxin?
bacteria produced toxin
Blocks the SNARE complex, and prevents ACh excocytosis-and if enough, NMJ wont work
Very very active, powerful -can kill millions with tiny tiny part
Used in botox -__-
