Cholinoceptor Antagonists Flashcards
(49 cards)
Where are nicotinic receptors found
All autonomic ganglia
What part of the ANS can nicotinic receptor ant/agonists interfere with
The whole ANS
What type of receptor is a nicotinic receptor
Type 1 ion channel
What 2 ways can a nicotinic receptor antagonist work
Can block the receptor or block the ion channel
what does use dependent blocking mean
drugs work most effectively when the ion channels are open. Thus, the more agonist that is present at the receptor, the more opportunity for the antagonist to block the channel, therefore, the more useful and effective these drugs can be
What makes a use dependent blocker more potent
If there is more agonist to open the ion channel
what is incomplete blocking
Ion channel blockers, they don’t completely block they slow it down considerably but not fully stop the functioning
Difference between normal receptor blockade and ion channel blockade regarding use dependency
When have a normal receptor blockade, then less agonist makes it more effective. Opposite is true for ion channel blockers
why do nicotinic receptor antagonists cause hypotension (2)
The SNS is dominant in blood vessels and the dominant effect is to constrict. This increases TPR and in turn, increases BP. The drugs take out the dominant sympathetic effect so the vessel will dilate. The TPR would decrease and so the BP would decrease.
Drugs might also interfere with the Renin secretion reduced aldosterone would be produced which means less water and Na is reabsorbed so less renin produced and thus, less ACE produced (see below).
Sympathetic dominated organ? (5)
Liver, kidney, adipose tissue, skin, blood vessels
PS dominated organ? (5)
Eyes, lungs, bladder/ureters/GIT
predominant method of action of trimetaphan
Receptor antagonism (but also ion channel blockade)
predominant method of action of hexamethonium
Ion channel blockade (but also receptor antagonism)
Use of trimetaphan?
IV for hypotension presurgery
other name for nicotinic receptor antagonist?
Ganglion blocking drugs
difference between receptor blockade antagonists and ganglion blocking drugs targets?
ganglion blocking drugs only target ANS nicotinic receptors, RBA can also target somatic NS
difference between receptor blockade antagonists and ganglion blocking drugs binding?
Ganglion blocking drugs are usually reversible RBA usually covalently bind and are irreversible
Another name for ganglion blocking drugs
Nicotinic receptor anatagonists
What part of the NS do muscarinic receptor antagonists target?
The PSNS
2 examples of muscarinic receptor antagonists?
Atropine, hyoscine
Where are muscarinic receptors predominantly found? Exception is?
In the PSNS effector organs, exception is the sweat glands
Atropine effects, normal and high dose?
Normal, does not do much.
High dose causes restlessness and CNS agitation
Hyoscine effects, normal and high dose?
Sedative/amnesia at normal dose, high dose causes CNS depression and paradoxical CNS excitation
Difference between hyoscine and atropine? What does this mean for its use
Hyoscine is more lipid soluble and so can penetrate the brain.
Other theory is that it is more M1 selective and so targets brain better.
