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CM - Pharm: Muscarinic Agents

Terms in this set (23)

parasympathetic response
-rest and digest
-decrease respiration
-decrease HR
-increase digestion
muscarinic agents
-produce a parasympathetic response depending on where in the body they are located
-have 5 muscarinic receptors but will focus on M2 and M3
What is the agonist of the muscarinic receptor?
ACh
-activates the receptor
-causes a rise in calcium uptake by the cell
-releases intracellularly stored calcium
-results in muscle contraction
What can block muscarinic receptors?
Atropine
-anticholinergic blocking agent
-intracellular Ca++ falls
-results in muscle relaxation
muscarinic receptor subtypes
-are postsynaptic membrane-bound muscarinic receptors targeted by drugs
-M2
-M3
M2
-muscarinic receptor subtype
-cardiac
-location: atria and conducting tissue of the heart
-function: cardiac inhibition
M3
-muscarinic receptor subtype
-glandular
-location: exocrine glands and smooth muscle
-function: lacrimal, salivary stimulation
bladder anatomy [img]
bladder physiology [img]
process of urination
-stimulate the detrusor muscles of the bladder
-relax the neck of the trigone of the bladder
M3 agonists in the bladder
-is activated by ACh
-causes detrusor muscle contraction
-is the driving force of bladder contraction
M3 antagonists in the bladder
causes detrusor muscle relaxation
beta 3 agonists in the bladder
-causes detrusor muscle relaxation
-is an M3 ACh antagonist
-can aggravate HTN
M2 agonists in the bladder
-is activated by ACh
-inhibits the sympathetic nervous system; says, "Beta 3, stop working."
alpha 1 agonists in the bladder neck/trigone
-on the urethral sphincter
-increases urethral sphincter tone
-causes bladder neck sphincter contraction
alpha 1 antagonists in the bladder neck/trigone
-causes bladder neck sphincter (tone) relaxation
-permits easier release of urine
-given to patients with enlarged prostates to initiate urination
-side effect = retrograde ejactulation
What would a drug that inhibits parasympathetic outflow do?
cause urinary retention by:
-relaxing the bladder
-increasing trigone tone
overactive bladder
-give a parasympatholytic drug
OR
-give a beta 3 adrenergic agonist but side effect will be aggravating HTN
uterus when NOT pregnant
beta 2 agonists causes relaxation
uterus when pregnant
-alpha 1 agonists cause contraction
-beta 2 agonists cause relaxation
A man with long standing diabetes experiences retrograde ejaculation due to bladder neuropathy (the nerves to his bladder have been damaged due to high glucose concentrations). What would giving the alpha-1 agonist Neosynephrine (phenylephrine) do for such a guy?
Alpha 1 agonist will contract the sphincter of the neck of the bladder, preventing sperm from going back into the bladder.
M3 agonist in the eye
-parasympathomimetic
-decreases intraocular eye pressure by causing ciliary muscle contraction
-this opens the trabecular meshwork and fluid flows out from the orbit
-fluid formed in the eye must escape and be cleared; if not will have a form of glaucoma
-but will have parasympathetic side effects
What are patients with too high of an intraocular pressure (glaucoma) treated with?
M3 agonists
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