Cholinoceptor antagonists Flashcards
Where can nicotinic receptors have its effect?
- they are always present on autonomic ganglia
- therefore they have the ability to interfere with the whole ANS
Where can drugs targeting muscarinic receptors have their effect?
- they are present within the effector organs of the PNS and sweat glands innervated by the SNS
- drugs effecting muscarinic receptors will be much more specific
What else are nicotinic receptor antagonists called and why?
- ganglion blocking drug
- they block the action of nicotinic receptors that lie at the ganglion
WHat 2 ways can you interfere with an ion-channel linked receptor?
- blocking the receptor
- blocking the ion channel
What are 2 clinical examples of nicotinic receptor antagonists?
- hexamethonium (better at blocking the channel pore)
- trimetaphan (better at blocking the channel receptor)
What determines the effect of the drug on the body?
- they are tissue specific, it depends which branch of the ANS predominates in a particular tissue
e. g if sympathetic predominates those effects will be lost and vise versa
Which tissues are sympathetically dominated?
- kidneys
- blood vessels
Which tissues are parasympathetically dominated?
- eyes
- lungs
- bladder, ureter, GI tract
What types of secretions will cholinoceptor blockade also stop?
-exocrine (cannot sweat and issues producing saliva)
what was hexamethonium used for?
-anti-hypertensive
why was hexamethonium suspended?
- wide side effect profile
e. .g loss of bladder control, pupil dilation, loss of GI motility
What is trimetaphan used for?
- surgery when controlled hypotension is needed
- very short acting
Where are receptor blockade antagonists mostly found?
- toxins and venoms
- irreversible they lead to a total loss of autonomic function
Why are muscarinic receptor antagonists more useful?
- more specific
- target parasympathetic effector organs and sweat glands vs everything
List 3 different muscarinic receptor antagonists
- atropine
- hyoscine
- tropicamide
