speth exam 2 Flashcards
most muscarinic agonists have quaternary ______ that is essential for binding to acetylcholine receptors
nitrogen
how is glaucoma treated? what receptor is this acting on?
pilocarpine contracts the pupillary sphincter muscle which relaxes the iris by acting on the M3 receptor as an agonist
this allows for better flow of aqueous humor out of the eye to decrease intraocular pressure
pilocarpine is selective for _______ ____ receptors
muscarinic ACh receptors (M3)
list examples of muscarinic agonists (hint: there are 6)
acetylcholine
methacholine
carbachol
bethanechol
pilocarpine
cevimeline
list the 5 uses of muscarinic antagonists
- dilates pupil for retinal examination
- treats excessive motility of GI tract (diarrhea, IBS)
- treats urinary incontinence
- treats COPD and asthma
- treats motion sickness
overall, do muscarinic antagonists increase or decrease parasympathetic activity?
decrease parasympathetic activity
how are muscarinic antagonists used to dilate the pupil for retinal examination? what receptor is used for this?
- increase sympathetic drive and decrease parasympathetic drive
- M3 receptor is stimulated to cause relaxation of the pupillary sphinctor muscle which increases pupil size
what is mydriasis?
pupil dilation
how is excessive motility of the GI tract and the urinary tract treated?
muscarinic antagonists block overactivity of the parasympathetic nervous system (rest and digest)
how are COPD and asthma treated? (include drug and mechanism). is this a muscarinic or adrenergic mechanism?
- can be both!
- mucarinic antagonist: tiotropium Br (Spiriva) blocks ACh which causes bronchoconstriction
- beta 2 adrenergic agonist
- decreases parasympathetic stimulation for bronchodilation
how is motion sickness treated? (include drug, receptor, and mechanism)
- scopolamine does not have quaternary nitrogen, so it is able to cross BBB and act on M1 muscarinic receptors
scopolamine causes ______ and ______
mydriasis and cycloplegia
what is cycloplegia?
paralysis of the ciliary muscle which results in dilation of the pupil and paralysis of accommodation (cannot see close objects)
what was atropine/belladonna used for in war? (explain the mechanism - hint: what does this block?)
atropine blocks acetylcholinesterase which causes a surge of acetylcholine
this causes bronchoconstriction and increased fluids in bronchial passages
this was useful for soldiers exposed to nerve gas (reduces flow of gas into lungs)
list the effects of anticholinergic agents using Dr. Speth’s mnemonic thing
- dry as a bone
- red as a beet
- hot as a hare
- blind as a bat
- mad as a hatter
what does “dry as a bone” mean in terms of anticholinergic agents?
causes very little peripheral dilation of cutaneous vessels
what does “red as a beet” mean in terms of anticholinergic agents?
causes flushing
what does “blind as a bat” mean in terms of anticholinergic agents?
inability to focus on things close up (cycloplegia)
what does “mad as a hatter” mean in terms of anticholinergic agents?
overdosing with antimuscarinic drugs can cause delirium
how long do atropine effects last?
6-10 days
what drug is closely related to atropine, treats motion sickness, causes anterograde amnesia, and is often used as a predatory drug? (hint: it is often called angel’s trumpet or natures poison?)
scopolamine
what is the source of scopolamine? (hint: it is known as the screaming plant in harry potter)
the mandrake mayapple
where is podophullum toxin found and what is it used for?
- found in the mandrake mayapple (with scopolamine)
- is an inhibitor of mitosis
- source of anti-cancer and anti-viral drugs
what is tropicamide and what is it used for?
- a synthetic agent that is similar to atropine and scopolamine but has a lower affinity for the receptor
- this lower affinity allows for shorter duration of effects
- used at the eye dr to dilate the pupils (effects only last 6 hours)
atropine effects last ____ days
scopolamine lasts ____ days
tropicamide lasts ____ hours - making it better for eye dilation exams
atropine = 6-12 days
scopolamine = 3-7 days
tropicamide = 6 hours
- will only have difficulty focusing and photophobia for 6 hours instead of days (this is why the dr uses this)
what are endogenous catecholamines?
hormones that act as neurotransmitters
what are the 3 uses of endogenous catecholamines?
- treats hypotension
- treats cardiogenic and septic shock
- treats anaphylaxis
how is shock treated
EPI and NE are given to increase BP (shock will decrease BP)
how is anaphylaxis treated?
By relaxing bronchiole smooth muscle
how is bradycardia treated?
NE and EPI are beta 1 agonists that increase HR
T or F: sympathetic agonists have similar functions to parasympathetic antagonists, and vice versa.
TRUE
what is the most potent catecholanine?
epinephrine
what receptor does epinephrine act on? what does this cause?
- causes contraction/vasoconstriction of arteries (A1 and A2)
- relaxes bronchial smooth muscle (B2)
what relaxes bronchial smooth muscle more: EPI or NE?
EPI
why is NE better than EPI for treating hypotension?
- NE will only act on alpha1 receptors (causing contraction of arterial strips) and has a low potency at B2 adrenergic receptors (which causes relaxation of bronchioles/skeletal muscle beds)
- EPI will interact with both A1 and B2
- NE is used because you only want to constrict to increase BP, not dilate
what will happen when NE is pretreated with phenoxybenzamine?
phenoxybenzamine is a competitive antagonist
- dose response curve shifts to right
what happens with NE is pretreated with a non-competitive antagonist?
will get a lower maximum response
isoproterenol is a endogenous catecholamine that is a ____ selective agonist
beta selective agonist (beta 1 and 2)
where is isoproterenol potent and not potent? (what receptor and what does this do?)
- most potent at B1 causing contraction of the heart
- potent at B2 causing relaxation of bronchial smooth muscle
- least potent for A1 (not good for contracting arteries)
phenylephrine is an ____ __ _____ receptor _____
phenylephrine is an alpha 1 adrenergic receptor agonist
what are the 5 uses of phenylephrine?
- treats nasal congestion
- treats hypotension
- treats shock
- induces mydriasis
phenylephrine drops in the eyes are an example of what?
a sympathetic agonist having similar effects to parasympathetic antagonist
how does phenylephrine treat hemorrhoids?
alpha 1 adrenergic agonist increases sympathetic stimulation
this increases vasoconstriction
what is an important aspect of the phenylephrine structure?
it has an alkyl chain with a methyl group
what is known as the “traitor” of sympathetic agonists? why is this?
alpha 2 adrenergic agonists are known as the “traitor” of sympathetic agonists.
This is because it causes inhibitory feedback. As EPI is released, the neuron will understand when there is too much, and will inhibit more release.
what are the uses of alpha 2 adrenergic receptor agonists? (hint: 3)
- treats hypertension
- treats ADHD
- treats neuropathic pain
how is hypertension treated by an alpha 2 adrenergic agonist?
inhibitory feedback of EPI release will decrease sympathetic drive
decreases BP, HR, CO, and vasoconstriction
amphetamine like drugs are used for what?
used as A2 adrenergic agonists to decrease ADHD symptoms
how is neuropathic pain treated by A2 adrenergic agonists?
any neuron with A2 adrenergic receptors will be inhibited (this includes pain fibers)