Cholinergic Agonists and Antagonists (Kruse) Flashcards

1
Q

Review:

What are the parasympathetic NTMs?

What are the parasympathetic receptors?

A

NTMs: Ach

Receptors: nAChR, mAchR

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2
Q

Review

What are the sympathetic NTMs>

What are the sympathetic receptors?

A

NTMs: Ne>Epi (DA); Ach

Receptors: a, B (D), nAchR, mAchR

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3
Q

What are the four events at the cholinergic nerve terminal?

A
  1. Ach synthesis
  2. Ach storage
  3. Ach release
  4. Ach destruction
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4
Q

What are the four events at the adrenergic nerve terminal?

A
  1. synthesis
  2. storage
  3. release
  4. reuptake
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5
Q

M1 receptors

Location:

Structure:

Mechanism:

A

Nerves

GPCR, Gq11

IP3, DAG cascade

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6
Q

M2

Location:

Structure:

Mechanism:

A

heart, nerves, Sm. muscle

GPCR, Gi/o

inhibits cAMP production, activates K channels

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7
Q

M3

Location:

Structure:

Mechanism:

A

Glands, Sm. muscle, endothelium

GPCR, Gq/11

IP3, DAG

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8
Q

M4

Location

Structure

Mechanism

A

CNS

GPCR, Gi/o

Inhibits cAMP production

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9
Q

M5

Location

Structure

Mechanism

A

CNS

GPCR/Gq11

IP3, DAG

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10
Q

Nn

Location

Structure

Mechanism

A

postganglionic cell body, dendrites, CNS

a and B only

Na, K depolarizing ion channel

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11
Q

In most organs, which receptor type is predominant?

Which receptor type predominates in the heart?

What are the most common receptor types in smooth muscle?

A

M3

M2

M3 and M2

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12
Q

What is the function of cholinergic agonists?

A

mimic the actions of Ach on nAchRs and mAchRs

classified based on MOA (direct or indirect)

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13
Q

what are the direct acting cholinergic agonists?

A

Acetylcholine

Methacholine

Carbachol

Bethanechol

metabolized by AchE

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14
Q

Does Ach display muscarinic or nicotinic action?

Does Methacholine display muscarinic or nicotinic actions?

Does Carbachol display muscarinic or nicotinic actions?

Does Bethanechol display muscarinic or nicotinic actions?

A

Both equally

Muscarinic only

both, but more nicotinic

Muscarinic only

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15
Q

Which direct cholinergic agonists are uncharged and highly absorbed

A

muscarine and pilocarpine (chiefly muscarinic acting)

nicotine and lobeline (chiefly nicotinic acting)

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16
Q

Which direct acting cholinergic agonists are charged and poorly absorbed?

A

Ach

Methacholine

Carbachol

Bethanechol

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17
Q

Indirect cholinergic agonists are also known as?

These come in three flavors. What are they?

A

AChE Inhibitors

Alcohols (reversible)

Carbamic Acid Esters (reversible, long lasting)

Organophosphates (irreversible, covalent)

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18
Q

Which AchE inhibitors are charged and poorly absorbed?

A

Neostigmine

Carbaryl

Physostigmine

Edophonium

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19
Q

Which AchE inhibitors are uncharged and highly absorbed?

A

Echothiophate

Soman

Parathion

Paraoxon

Malathion

Malaoxon

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20
Q

What are some general parasympathetic effects of cholinergic agonists?

A

Miosis

decreased HR, contraction and conduction velocity

vasodilation in low dose, vasoconstriction in high dose

bronchoconstriction and increased secretions

increased GI motility with sphincter relaxation and increased secretions

contracts detrusor in bladder and relaxes trigone and sphincter

sweat secretions

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21
Q

What are the major uses of direct acting cholinergic agonists?

A

glaucoma and accomodative esotropia (crossed-eyes)

post-op ileus

congenital megacolon

urinary retention

GERD

xerostomia/Sjogren’s

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22
Q

What are the symptoms of toxicity with direct acting muscarinic stimulants?

A

N/V/D, urinary urgency

salivation/sweating

vasodilation

bronchoconstirction

SLUDGE (increased gland secretions)

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23
Q

Muscarinic stimulants (direct acting cholinergic agonists) are contraindicated in whom?

A

pts with asthma, hyperthyroidism, coronary insuffiency and acid peptic disease

24
Q

What are the symptoms of toxicity in direct-acting nicotinic stimulants?

A

nicotinic poisoning: from cigarettes or insecticides

causes CNS stimulation, skeletal muscle endplate depolarization, resp. paralysis, hypertension, cardiac arrhythmias

tx with atropine and parenteral anticonvulsants

25
Ach is used for what issues?
intraocular use during surgery to cause miosis (pupil constriction)
26
What is bethanechol used for?
Selective mAchR agonist that primarily affects GU tracts used to treat urinary retention and heartburn little cardio stimulation may increase risk for UTIs due to failure of sphincter relaxation
27
What is carbachol used for?
nonspecific cholinergic agonist used for the treatment of glaucoma or to produce miosis during surgery or eye exam
28
What is cevimeline used for?
oral tablet used to treat dry mouth in pts with Sjogrens
29
What is Pilocarpine used for?
xerostomia in pts with Sjogren's. induce miosis in eye procedures and glaucoma it is a pure mAchR agonist
30
What is Varenicline?
used for smoking cessation partial agonist that binds with high affinity and selectivity to **a4B2 nAChR (Nn)** **MOA**: stimulates a moderate and sustained release of mesolimbic dopamine to reduce craving and withdrawal from nicotine may cause nasuea and neuro-psych sx (SI, depression)
31
How are indirect-acting cholinergic agonists used for glaucoma?
stimulates mAchR on ciliary body to facilitate aq. humor outflow and reduce intraocular pressure (replaced by B-blockers and prostaglandins)
32
How are indirect-acting cholinergic agonists used to treat dementia from Alzheimer's and Parkinson Disease?
AD pts have a deficiency of intact cholinergic neurons
33
What is used as an antidote for anticholinergic poisoning? What causes it? What are the sx of it?
Indirect-acting cholinergic agonists anticholinergic poisoning can be caused by atropine, antihistamines, TCAs, sleep aids, cold preparations sx-vasodilation, anhidrosis, anhydrotic hyperthermia, nonreactive mydirasis (dilated pupils), delirium, hallucinations, reduced urine
34
Indirect-acting cholinergic agonists are also used for what?
reversing neuromuscular paralysis (in surgery) Myasthenia Gravis
35
AchE inhibitor toxicity can be treated by what?
indirect-acting cholinergic agonists, specifically atropine, maintaining vitals, decontamination, pralidoxime causes SLUDGE and NMJ effects
36
What are the two classes of cholinergic antagonists?
muscarinic and nicotinic
37
What are the two targets of antinicotinic agents?
neuromuscular junction (ske. muscle relaxants) ganglia (rarely used)
38
What are the targets of antimuscarinic agents? how do they work?
CNS, nerves, heart, smo. muscle, glands, endothelium block the effects of the parasympathetic autonomic discharge most clinically used ex: atropine
39
Anticholinergics used for motion sickness?
Scopolamine
40
Anticholinergics used for GI disorders
Atropine Dicyclomine Glycopyrroleate Hysoscyamine
41
Anticholinergic agents used in ophthalmology
atropine cyclopentolate homatropine scopolamine tropicamide
42
anticholinergics used for respiratory disorders
ipratropium tiotropium
43
anticholinergic agents used for urinary disorders
darifenacin oxybutynin solifenacin tolterodine tropspium
44
anticholinergics used for cholinergic poisoning
atropine (+pralidoxime)
45
anticholinergics used for movement disorders
benztropine biperiden orphenadrine procyclidine trihexyphenidyl
46
What are the general effects of anticholinergics?
incresae sympathetic tone constrict muscles, tachycardia bronchodilation and reduced secretions supresses thermoregulation sedation/drowsiness
47
How are anticholinergics used in Parkinson's Disease?
mAchR antagonists can reduce tremoris not as effective as dopaminergic therapy, often used in combination specific drugs: tertiary amines benzotropine, trihyxyphenidyl, procyclidine
48
Scopolamine for motion sickness can be administered three ways
PO injection transdermal
49
how are anticholinergics used for anesthesia?
atropine is given to block responses to vagal refluxes induced by surgical manipulation of visceral organs atropine or glycopyrrolate is paired with the cholinesterase inhibitor neostigmine to block its parasympathetic effects
50
When are mAchR antagonists used in ophthalmologic disorders?
mAchR antagonists are only used when cycloplegia or prolonged mydriasis is required like after LASIK a-adrenergic receptor agonists are shorter acting and produce less adverse effects and can be used as well/instead
51
When are homatropine and atropine used in ophthalmogic disorders?
homatropine and atropine are used to prevent synechia formation in uveitis and iritis long acting agents mydriasis may last 6 hours to 12 days and cycloplegia persists 10hrs to 14 days
52
How is ipratropium and tiotropium used for asthma and COPD (anticholinergics)
these are inhaled mAChR antagonists Tiotropium has a longer bronchodilator action than ipratropium and can be dosed once daily
53
how are mAchR antagonists used for GI issues?
can be used to treat traveler's diarrhea and other hypermotility issues, limited use. May be combined with opioid antidiarrheal Ex: Lomotil
54
How are mAchR antagonists used for GU disorders?
treat urinary urgency agents with selectivity for M3 mAchR work well because of their presence in bladder wall and sphincter muscle Oxybutinin is an example but causes dry eye/mouth, dizziness, constipation, blurred vision Darifenacin, solifenacin, and tolterodine also work the same way and have longer half-lives and reduced side effects
55
What causes cholinergic poisoning?
cholinesterase inhibitor insecticides, wild mushrooms, warfare nerve gases give Atropine for CNS and pralidoxime for peripheral NS atropine is useless in delayed onset mushroom poisoining characterized by n/v 6-12 hours after ingestion and causes hepatic/renal damage
56
High systemic concentrations of anticholinergics can cause the following?
blocked parasympathetic function dry as a bone, blind as a bat, red as a beet, mad as a hatter, hot as a hare treat with ACE inhibitors or symptomatically Contraindicated in people with glaucoma, BPH, acid peptic disease