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Cholinergic Drugs
Dr. Pamidimukkala 8/22/12
67
Pharmacology
Post-Graduate
09/11/2012

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Term
What are the classes and subclasses of Cholinergic drugs?
Definition
Cholinomimetics/parasympathomimetics:
1. Direct acting ones - Cholinergic agonists
2. Indirect acting ones - acetylcholinesterase inhibitors
Cholinergic antagonists/parasympatholytics
1. Muscarinic Antagonists
2. Nictoinic antagonists (ganglionic blockers and neuromuscular blockers)
Term
Name 1 choline ester and the receptor it targets.
Definition
Bethanechol - MUSCARINIC (bladder and GI hypotonia)
Term
What is a new M3 specific agonist? WHen is it used?
Definition
Cevimeline...to treat dry mouth in Sjorgen's syndrome patients
Term
Name 2 natural alkaloids that are choinergic agonists and the receptor they target.
Definition
Muscarine - from mushroom; obvi muscarinic receptor (that's how they discovered the diff. receptors)
Pilocarpine - muscarinic (glaucoma)
Term
When do we use bethanechol?
Definition
WITH PATIENTS THAT HAVE DECREASED PARASYMPATHETIC TONE:
Postoperative/postpartum - urinary retention and/or inadequate emptying of bladder
Postoperative abdominal distension or GI tract atony or paresis.
Term
Where does bethanechol work?
Definition
M3's in urinary bladder, GI
Term
When do we use pilocarpine?
Definition
Glaucoma or xerostomia (dry mouth)
Term
What reverses the effect of atropine after an eye exam?
Definition
Pilocarpine - activates sphincter pupillae to constrict pupil (M3)
Term
What does the eye tolerate better: pilocarpine or AChE inhibitors?
Definition
Pilocarpine
Term
How does pilocarpine decrease IOP?
Definition
constricts pupil , which reduces the angle block???? via M3
Term
What is a warning with pilocarpine use?
Definition
Its a tertiary amine, therefore is kinda hydrophobic, therefore can get into the systemic system more easily....so we can see some parasym. responses nearby like runny nose
Term
How does pilocarpine work on the salivary gland?
Definition
AChR agonist acts on M3 on salivary gland to increase secretion
Term
Which one of these drugs is preferred for xerostomia? Pilcarpine, bethanechol, or cevimeline?
Definition
Cevimeline - greatest affinity for M3 on the salivary gland than the other 2. Less side effects
Term
When do we use cevimeline?
Definition
Irradiation of head/neck (destroys salivary gland and we need to get out as much as possible)
Xerostomia assoicated with Sjogren's syndrome
Term
What is the special features of the MOA of cevimeline?
Definition
M3 agonist which is more selective, potent in action at the salivary and lacrimal glands than others.
Term
What the side effects of muscarinic agonists?
Definition
Diarrhea, Diaphoresis (sweat glands have muscarinic receptors), Miosis, Nausea, salivation, urinary urgency, CNS disturbances (for substances that can cross BBB - like pilocarpine)
Term
What are the 2 contraindications for muscarinic agonists?
Definition
ASTHMA (increases bronchoconstriction and increased mucous secretion)
HEART DISEASE (slow conductivity of heart - M2's but still agonized by agonists designed to target M3's - arrhythmias can develop)
Term
What are pseudo cholinesterases?
Definition
non-specific, circulating esterases that cleave any ester bond.
This is why we cannot clinically use ACh
Term
Where can AChE inhibitots work?
Definition
Anywhere pretty much -
All visceral parasympathetics
NMJ
ALL autonomic ganglia
Term
-stigmine drugs are usually what? What other one with this too?
Definition
AChE inhibitors; -onium
Term
Where does neostigmine work? Can it X BBB?
Definition
Neuromuscular junction mostly! No, cannot X BBB.
Term
What drug is the best for treating myasthenia gravis? Why?
Definition
Neostigmine....greatest effects at NMJ (better than physostigmine)
Term
What are some adverse effects of Neostigmine?
Definition
generalized cholinergic stimulation and drop in BP
Overdose: cholinergic crisis and muscle paralysis (via densitization from too much ACh)
Term
What is physostigmine used for? Can it X BBB?
Definition
Antidote for atropine overdose (and other anticholinergics)
Reduces intraoccular pressure in glucoma (same mech. as pilocarpine)
Hypotonia of bladder and GI
YES can X BBB cuz its tertiary amine
Term
What are some adverse side effects of physostigmine? What about super high doses?
Definition
Diarrhea, nausea, sweating, miosis, urinary urgency
High doses: convulsions (its Xed BBB), bradycardia and hypotension
Term
What are the symptoms of organophosphate poisoning? pneumonic? others not in pneumonic?
Definition
SLUD - salivation, lacrimation, urination, defecation
Others: miosis, GI motility, emesis/vomitting and MAYBE confusion/halucinations if Xed BBB
Term
What do organophosphates do?
Definition
Irreversible, long-lasting AChE inhibitor
They phosphorylate AChE...which will be degraded over time (called "aging"). Therefore it is considered an IRREVERSIBLE drug (after the point of aging)
Aging can be 2 mins to hours, depends
Term
How do we treat organophosphate or nerve gas poisoning prophylactically and post-exposure?
Definition
Prophylaxis: Pyridostigmine if in danger of chemical warfare...this drug will block the site the poison is attempting to phosphorylate
Post exposure: Use of muscarinic antagonists (atropine or scopolamine). This will inhibit all those extra ACh activity the organophosphates caused. An injection of PRALIDOXIME can chemically dephosphorylate AChE (rendering it active again) but ONLY before the "aging" process has occured.
Term
Edrophonium is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
SHORT (the only short), therefore REVERSIBLE
Term
Physostigmine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Neostigmine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Pyridostigmine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Rivastigmine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Galantamine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Ambenonium is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Donepezil is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Tacrine is a ____-acting ______ (rev./irrev.) AChE inhibitor
Definition
intermediate; reversible
Term
Name 2 synthetic organophosphates. What is their mode of inhibition and time frame
Definition
BOTH are long-lasting IRREVERSIBLE inhbitors of AChE
Ecothiophate
Isofluorophate
Term
Name 2 nerve gases. What is their mode of inhibition and time frame
Definition
Both are long-term and irreversible to AChE.
Sarin and Soman
Term
Name 4 AChE inhibitors that treat myasthenia gravis.
Definition
Edrophonium (short - diagnostic test only)
Neostigmine
Pyridostigmine
Ambenonium
Term
What AChE inhibitor treats hypotonia of bladder and GI?
Definition
Physostigmine
Term
What 2 AChE inhibitors treat Glaucoma?
Definition
Physostigmine and Ecothiophate
Term
What 4 drugs treat alzherimers? What is the MOA? What is their unique characteristics?
Definition
They ALL must X the BBB
They are all AChE inhibitors
Donepezil, Rivastigmine, Tacrine, Galantamine
Term
Name 2 belladona alkaloids? What do they do?
Definition
Atropine
Scopolamine
Muscarinic ANTAGONISTS
Term
Name 3 muscarinic antagonists that are synthetic.
Definition
Ipratropium
Tiotropium
Tolterodine
Term
What is the clinical use of atropine?
Definition
Severe bradycardia
To produce mydriasis and cycloplegia (loss of accomodation) for exam of eye
Suppress respiratory secretions prior to surgery
Treat organophosphate (AChE inhibitors) poisoning & mushroom poisoning
Term
What is cyloplegia and what causes it?
Definition
Loss of accomodation of the eye...used during eye exams via ATROPINE
Term
What gets thru the BBB: atropine or scopolamine?
Definition
Both, but only scopolamine to a therapeutic level
Term
What is atropine used for?
Definition
Mydriasis, cycloplegia, reduction in GI motility and reduction of salivary,sweat, and lacrimal secretions
Term
What are the side effects of atropine?
Definition
Dry mouth, constipation, dilated pupils, blurred vision, hot/dry/flushed skin, tachycardia, fever, CNS disturbances (at very very high levels)
Term
What is the lowest amount of atropine we give? Why?
Definition
2.0 mg...anything under will actually decrease HR even more (complicated explaination)
Term
When is scopolamine used?
Definition
Sea sickness, opthalmic use, adjunct drug in anesthesia to produce sedation/amnesia
Term
What are the side effects of scopolamine?
Definition
much greater CNS side effects: drowsiness, amnesia, fatigue, loss of REM sleep
Term
What is ipratropium bromide used for?
Definition
Asthma and COPD as a bronchodilator in adjunct to albuterol
OR just ipratropium Br by itself if patient cannot tolerate adrenergic agonists
Term
What is the MOA of ipratropium bromide?
Definition
Blockage of muscarinic receptors causing bronchodilation (but not very much decrease in mucocilliary clearance)
Term
What is tiotropium bromide
Definition
Muscarinic antagonist that has a GREATER ACTIVITY for M3 vs M2, therefore used in Asthma and COPD, with selective action toward the bronchioles
Term
What is tolterodine?
Definition
Muscarinic antagonist. Used to treat overactive bladder (reduce incontinence, frequecy, urge, and increase the amt of urine bladder can hold)
Term
What is the MOA of tolterodine?
Definition
Muscarinic antagonist...blocks M3 receptors on bladder and sphincter and calms down an overactive bladder
Term
WHat is the contraindication of M3 antagonists?
Definition
Slow voiding (urinary retention)
EX - BPH
Term
What are the contraindications for giving muscarinic antagonists?
Definition
Glaucoma, BPH or any urinary/kidney condidtion, excessive constipation, myasthenia gravis (cuz when used with AChE inhibitor will MASK the symptoms of cholinergic crisis, which is something you NEED to be able to detect)
Term
Name some ganglionic blockers (nicotinic antagonists)
Definition
There are no nicotinic antagonists that act on the ganglions...at least none we need to know cuz they're never used
Term
Name the non-depolarizing NMJ blockers
Definition
Atracurium, cistracurium, vecuronium, rocuronium, pancuronium, tubocurarine
Term
Name the depolarizing NMJ blockers
Definition
Succinyl Choline
Term
What is succinyl choline? How is it broken down?
Definition
2 ACh's linked at one end
Plasma cholinesterases degrade and NOT AChE's
Term
Succinylcholines have a ____ onset and ____ duration
Definition
rapid; short
Term
Contrast Phase I and Phase II of depolarizing blockers MOA.
Definition
Phase I: SuCh acts as ACh and causes muscle fasiculation via depolarization, etc until receptors are desensitized. During phase 1, addition of AChE inhibitor will WORSEN the paralysis effects in the end.
Phase II: SuCh might be blocking the nicotinic ion channels but either way receptors are desenstized by phase I and not even huge amounts of ACh can cause contraction, therefore AChE inhibitiors (which increase ACh at NMJ) would be worthless)
Term
What are some side effects of succinylcholine?
Definition
Muscle pain, hyperkalemia, blockage of ganglionic nictoinic receptors (decreased HR, increased IOP), MALIGNANT HYPERTHERMIA
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