Test 2 Cholinergics Flashcards

1
Q

Nicotine

A

Stimulates Nn receptors. Used for smoking cessation

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2
Q

Succinylcholine

A

Muscle relaxant during intubation/convulsive shock therapy.

Remains on Nm receptors, causing depolarization block. The constant stimulation of the receptors prevents repolarization of the neuron.

Contra: Familial hyperthermia, skeletal muscle myopathies

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3
Q

Acetylcholine

A

Muscarinic and nicotinic agonist

Binds nicotinic and muscarinic receptors. Rapidly hydrolyzed by AchE and plasma cholinesterase, so it is not useful therapeutically.

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4
Q

Methacholine

A

Stimulates muscarinic receptors. Resists hydrolysis by AchE.

Use: Diagnose bronchial hyperactivity in cases of suspected asthma.

Tox: Bronchiolar constriction

Contra: β-blockers (overdose antidote is β-agonist treatment)

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5
Q

Carbachol

A

Muscarinic and nicotinic agonist, resist hydrolysis by AchE.

Use: Topical miotic (constriction of pupil) agent for ocular surgery and glaucoma.

Tox: Excessive muscarinic activity (eg. bronchoconstriction, decreased cardiac conduction)

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6
Q

Bethanechol

A

Selective muscarinic agonist (and low M2 affinity, so decreased cardiac effect). Resists hydrolysis by AchE.

Use: Treatment of post-op urinary retention and neurogenic bladder atony (esp targets receptors in GI and on urinary bladder)

Tox: Bradycardia and bronchoconstriction

Contra: Asthma, peptic ulcer (don’t want to stimulate secretions), bradycardia

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7
Q

Muscarine

A

Muscarinic agonist. No medicinal use; gives profound parasympathetic stimulation. Treat w/ atropine (muscarinic antagonist) if ingested.

From Clitocybe dealbata (a mushroom).

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8
Q

Pilocarpine

A

Non-selective muscarinic agonist, crosses BBB.

Use: Dry mouth due to head and neck radiotherapy or Sjogren’s syndrome (Ab destruction of salivary glands). Treatment of open-angle glaucoma.

Tox: Excessive muscarinic activation (slowed AV nodal conduction), hypotension, excessive salivation, and bronchoconstriction.

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9
Q

Neostigmine

A

Reversible inhibitor of Acetylcholinesterase, and has direct stimulation of nicotinic receptors at skeletal muscle endplate (NMJ).

Use: Myasthenia gravis (Ab attack of skeletal muscle nicotinic receptors), and reversal of neurotransmitter blockade.

Tox: Muscarinic and nicotinic excess.

Contra: Intestinal obstruction (don’t want to stimulate motility if the intestine is blocked).

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10
Q

Edrophonium

A

Inhibits cholinesterases and stimulates nicotinic receptors at NMJ. Very rapid and short duration of action, readily crosses BBB.

Use: To establish diagnosis of myasthenia gravis, or as a differential between progression of myasthenic weakness and cholinergic crisis (due to excess Ach) resulting from cholinesterase toxicity (neuromuscular block mimicking M.G. because of excess stimulation of Ach receptors).

Tox: Bradycardia, cardiac standstill

Contra: intestinal blockage, urinary obs.

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11
Q

Physostigmine

A

Inhibits cholinesterases. Long duration of action (t1/2 = 2hours). Readily crosses BBB.

Use: To counteract delirium secondary to excess anticholinergic activation (atropine poisoning).

Tox: Convulsions, respiratory and CV depression.

Contra: Asthma, CV disease, intestinal obstruction

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12
Q

Donepezil

A

Reversible CNS acetylcholinesterase (specifically) inhibitor.

Use: Treatment of Alzheimer’s disease.

Long half-life allows for once a day oral dosing.

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13
Q

Organophosphates

A

Irreversible cholinesterase inhibitor.

DUMBBELS (diarrhea, urination, miosis, bradycardia, bronchorrhea, emesis, lacrimation, salivation)

Treat with ventilation, suction of tracheal secretion, atropine (anti-muscarinic agent), 2-PAM (pralidoxamine chloride) to reactivate AchE.

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14
Q

Echothiophate

A

Irreversible AchE inhibitor used clinically.

Use: Long term miosis in the treatment of open-angle glaucoma (topically administered).

The goal is to stretch the trabecular network, but this leads to blurry vision. So this drug is usually only given to the elderly.

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15
Q

Atropine

A

Muscarinic antagonist

Use: 1) Allaying urgency and frequency of micturition (urination) associated with UTI.

2) Relieve hypermotility of colon and hypertonicity of SI.
3) Cholinesterase inhibitor induced poisoning (organophosphates)
4) Induce mydriasis (dilation) and cycloplegia (paralysis of ciliary muscle of eye)
5) Reverse bradycardia of vagal origin

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16
Q

Scopolamine

A

Muscarinic antagonist.

Use: Preparation for surgery to minimize secretions. To treat nausea and vomiting associated with motion sickness, and chemotherapy induced nausea.

Contra: Narrow/closed-angle glaucoma

17
Q

Glycopyrrolate

A

Muscarinic antagonist. Does not cross BBB.

Use: Protects against excessive muscarinic effects of AchE inhibitors used during reversal of neuromuscular blockade. Pre-op anti-sialogogue (decrease salivation).

Tox: Heat stroke because of the inability to sweat.

So after surgery you would give neostigmine (AchE inhibitor) to reverse the muscle relaxant, and glycopyrrolate to prevent the overstimulation of gut by the neostigmine.