Pharmacologie: Partie 2: Pharmacologie du système nerveux autonome, Cholinomimétiques /Anticholinergiques Flashcards

1
Q

What are cholinomimétiques?

A

Molecules that mimic the effect of acetylcholine

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2
Q

What are the two main types of cholinimimétiques?

A
  1. Action directe (bind to the receptor itself) CHAD
  2. Action indirecte (increase ACh that is secreted/produced) CHAID
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3
Q

How do CHADs work?

A

Effected mediated by molecule binding to and stimulating receptors

Two kinds: amines quaternaires (can’t pass BBB) and tertiaires (can pass BBB)

Susceptible to being hydrolyzed by cholinestérases

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4
Q

What are the two sous-types of CHADs?

A
  1. Nicotiniques
  2. Muscariniques (parasympathomimétiques)
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5
Q

Where are Nicotiniques found?

A

Ganglions autonomes: PNS and SNS

Neuromuscular junctions

CNS

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6
Q

If nicotinique (in PNS and SNS) are stimulated.. it will lead to what?

A

Release of Ach by postganglionary PSN neurons

Release of catecholamines by médullo-surrénales

Release of NA by postganglionnary SNS neurons

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7
Q

If nicotinique (neuromuscular junction) are stimulated.. it will lead to what?

A

Stimulation of post-synaptic receptors of neuromuscular junction

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8
Q

What will happen if these receptors are stimulated repeatedly and excessively? (nicotinique)

A
  1. Desensitization of neurons
  2. Inhibition of transmission ganglionnaire
  3. Diminished release of catecholamines by adrenals
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9
Q

What is the clinical effect of stimulation of these receptors by CHADs? (nicotinique)

A

Vasocontriction

Tachycardia

Increased GI motility

Incontinence/urgency (urination)

Muscle contraction

General CNS effects

CAN LEAD TO ADDICTION —> DOPAMINE RECEPTORS

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10
Q

What are the clinical uses of nicotinic CHADs?

A

Not many, other that nicotine patches or other treatments for cigarette addiction

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11
Q

Where are the global effects of stimulating muscarinic receptors?

A

Stimulation of PNS

Light inhibition of PNS and SNS (auto/heteroregulation)

Stimulation of SNS (sweatglands)

NO IMPACT ON MÉDULLO-SURRÉNALE

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12
Q

What are the effects of direct stimulation of muscarinic receptors? (PNS)

A

Myosis

Increase in lacrymal and salivary secretions

Increase in peristalsis

Vasodilation (not PNS.. but muscarinic receptors directly on vessels)

Bradycardia

Bronchoconstriction and increase in tracheal secretions

Increased GI motility

Relaxation of GI sphincters

Contraction of detrusor muscle and relaxation of vesical sphincter

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13
Q

What are some clinical uses for muscarinic CHADs?

A

Glaucoma: reduce intraocular pressure by inducing a myosis

Metacholine tests for diagnosing asthma: induce bronchoconstriction

Treating xerostomia resulting from Sjogrens or radiotherapy to increase salivary and lacrimal secretions

Correction of atonic bladder and urinary retention

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14
Q

What is muscarin?

A

Muscarinic agonist: activates the activity of the muscarinic acetylcholine receptor

Parasympathomimetic symptoms (hypersecretion, vomiting, diarrhea, dehydration, myosis)

Antidote: Atropine —> muscarinic antagonist

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15
Q

What is sarin gaz?

A

Liquid without smell or colour in the family of organophosphates

Irreversible inhibitors of acetylcholinesterase

Muscular contractions that may lead to paralysis, myosis, hypersecretions, bronchospasm, dyspnea, nausea, vomiting, incontinence

Antidotes: pralidoxime and atropine

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16
Q

What are the three important cholinomimétiques to know?

A

Methacholine, neostigmine and organophosphates (like Sarin)

17
Q

What are anticholinergiques?

A

Antagonists for muscarinic and nicotinic receptors (ganglia, muscular)

They inhibit liberation of ACh

18
Q

What are antimuscarinics?

A

They block muscarinic receptors (ex: atropine and glycopyrrolate)… not much selectivity for sub-types

They’re considered parasympatholytic

Tertiary (✅ BBB) and quaternary (❌ BBB) amines

19
Q

Where do antimuscarinics primarily work?

A

Autoregulation in PSYMP and hetero in SYM (pre-synaptic)

Block post-synaptic muscarin receptors (Ach) in PSYMP

20
Q

What are antimuscarinics principal effects?

A

Mydriasis

Cycloplegia (paralysis of the ciliary muscle)

Tachycardia

Bronchodilation

Urinary retention

21
Q

What are some clinical uses of antimuscarinics?

A

Bradycardia treatment (atropine)

Treatment of bronchospasm in MPOC and asthma

Dilate pupils during ophthalmological exam

Preventing nausea/vomiting, reducing saliva secretion, sedation

Parkinsons: reduce shaking/rigidity

Reducing spasms but LOTS of side effects

Reversing effects of neuromuscular blockers and intoxication from cholinomimétiques (atropine)

22
Q

What conditions are counter indications to prescribing antimuscarinics?

A

Glaucoma, urinary retention and prostatic hyperplasia, constipation, hyperthermia (fever), tachyarrhythmia

23
Q

What are ganglioplégiques?

A

Antagonists for Ng receptors (nicotiniques ganglionnaires) (ex: triméthaphan)

24
Q

Where do ganglioplégiques primarily target?

A

block symp >>> parasymp

inhibits transmission between preganglionic and postganglionic neurons in the autonomic nervous system, often by acting as a nicotinic receptor antagonist

25
Q

What are some clinical uses of ganglioplégiques?

A

Treating hypertension BUT THEY SUCK DON’T USE THEM

26
Q

What are neuromuscular blockers?

A

lead to paralysis of skeletal muscles (ex: rocuronium –> sedative)

27
Q

Where do neuromuscular blockers target?

A

antagonist of nicotinic muscular receptors

28
Q

What are some clinical uses of neuromuscular blockers?

A

Mostly used for paralysis: preoperatory, endotracheal intubation and in the ICU (rocuronium)

29
Q

How does toxine botulinique work?

A

Bonds irreversibly to cholinergenic nervous fibres and stops liberation of ACh

30
Q

What is botulism and how is it treated?

A

Rare and potentially fatal illness caused by a toxin produced by the bacterium Clostridium botulinum

Causes: vision problems, mydriasis, ptosis, difficulty swallowing, constipation, muscular weakness and paralysis BUT normal sensitivity and afebrile

Treatment: Antitoxine équine (MUST BE GIVEN VERY EARLY)

31
Q

What is botox used for?

A

Used for: treating spasticity, aesthetics, can be injected into ureter, bladder and prostate for medical treatments

32
Q

What do supratherapeutic doses of atropine cause? And how is this treated?

A

Can lead to intoxication… symptoms include: excitation, nervousness, hallucinations, coma

Treatment: Physostigmine (cholinesterase inhibitor that can cross BBB) which will inhibit central effects of atropine