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Pharma 1 > Cholinergic Agonists and Cholinesterase Inhibitors > Flashcards

Cholinergic Agonists and Cholinesterase Inhibitors Flashcards

1
Q

Sites of ACh Action

A

Post Ggl Nerve Endings: Muscarinic

Symp and Parasymp Ggl: Nicotinic

NMJ: Nicotinic

CNS: Muscarinic and Nicotinic

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2
Q

Definition of Cholinergic Agonists

A

Substances which activate nicotinic or muscarinic Rs

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3
Q

Nicotinic R

Localisation
Structure

A

Muscle (NMJ): Stimulation
Ggl: Stimulation
CNS
Adrenal Medulla: Secretion of epinephrine and NE

Ionotropic
Agonist binding-> ion channel (Na/K) opening

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4
Q

Muscarinic R

Types

A

M1: Neural Gq

M2: Cardiac Gi and modulates muscarinic K Channels

M3: Glandular/SM Gq

Also have M4 and M5

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5
Q

Cholinergic Agonists

A

All 4 Amine, can’t cross BBB

ACh: Endogenous, nonselective; no medical use

Muscarine: Muscarinic R Agonist, fungal toxin
No medical use

Carbachol: Non specific, no medical use

Bethanchol: M R agonist
Uses: SV Arrythmias, Atonic Bladder Paralytic Ileus
Prokinetic: Increase GIT motility

Pilocarpine: M R agonist
Uses: Glaucoma; contracts ciliary muscles, opens
Schlemm canal

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6
Q

Pharmacological Effects of Agonists

General

A

Occular

Cardiac

Vascular

Pulmonary

GIT

Urogenital

Other glands: Tear, sweat

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7
Q

Pharmacological Effects of Agonists

Occular

A

Via M3: Gq

Miosis
Accommodation

–> decrease intraocular pressure

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8
Q

Pharmacological Effects of Agonists

Cardiac

A

Via M2: Gi

Negatve chrono-, bromo- bathmo- and inotropic

–> Bethanchol

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9
Q

Pharmacological Effects of Agonists

Vascular

A

Via M3: Gq

Usually no PS innervation of blood vessels, but increase ACh-> release of NO by endothelial cells-> relaxation

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10
Q

Pharmacological Effects of Agonists

Pulmonary

A

Via M3: Gq

Vagus Nerve innervates bronchial SM-> bronchoconstriction and increased bronchial secretion

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11
Q

Pharmacological Effects of Agonists

GIT

A

Via M1 and M3

M1: Parietal cells: Stimulation of gastric acid secretion

M3: Increased motility; relaxation of sphincters

–> Betanchol

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12
Q

Pharmacological Effects of Agonists

Urogenital

A

Via M3

Contraction of M. Detrussor Urinae-> urination

–> Betanchol

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13
Q

Pharmacological Effects of Agonists

General SE

A 
Muscarinic Effects
   Diarrhoea
   Vomiting
   Bronchoconstriction
   Bradycardia
   Lacrimation
   Salivation
   Sweating
   CNS Stimulation

Nicotinic Effects:
Skeletal muscle excitation, then paralysis
CNS stimulation

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14
Q

Cholinesterase Inhibitor

General Background

A

Indirect cholinomimmetics
Inhibit degradation

Types:
Acetylcholinesterase (mainly synaptic cleft)
Butyrylcholinesterase (plasma, skin, brain, liver, GIT)

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15
Q

Cholinesterase Inhibitor

Short Duration of Action

A

Edrophonium

4, useless for therapy

Used in diagnosis of Myasthenia Gravis

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16
Q

Cholinesterase Inhibitor

Intermediate Duration of Action

A

Neostigmine
4, decurarisation

Physostigmine
3
Clinical uses: Glaucoma, MG, reverse action of
tuburocuranine, bladder and intestinal atonia
((Alzheimers))

17
Q

Cholinesterase Inhibitor

Irreversible

A

Echothiophate: Eyedrops for chronic glaucoma

Parathion and Malathion: Insecticides
Are organophosphates

Sarin: Nerve gas–> Atropine to prevent (against M effects)
Also organophosphate

Can cause cholinergic crisis

18
Q

Cholinergic Crisis

A

Stimualtion of ggl-> depolarising block (desensitisation)
No antidote against ggl stimulation: anticonvulsants

activates PS-> brady, bronchoconst, diarrhoea, miosis

NMJ depolarising block

convulsions, tremor, ataxia, inhibition of resp center

Treatment
Decontamination: wash skin, remove clothing
IV Atropine until salivation stops

19
Q

Pralidoxine and Obidoxine

A

-> Removal of irreversible cholinesterase inhibitors

Can be given up to 6 hrs post poisoning

But as 4-> can’t enter CNS-> still need artificial ventilation

20
Q

Rivastigmine

A

Inhibits Acetyl- and Butyrylcholinesterase

Used in Alzheimers th

21
Q

Toxicity of Insecticides (Activation)

A

Parathion (inactive) activated by CYP450-> Paraoxon

Paraoxon (active) via CYP450-> Inactive compounds

22
Q

Cholinergic ‘Pathway’

A

Choline + Acetyl CoA–> ACh
by Choline Acetyl Transferase

ACh then exists cell-> cleft where acts on either M or N R

Or degraded into Choline and Acetate
by Acetylcholine esterase

Pharma 1 (15 decks)

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