Cholinergic System Flashcards by Richhpal Singh

PNS originates from

Craniosacral outflow
Cranial nerves - ii, vii, ix, x
Sacral - S2,3,4

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Neurotransmitter in PNS

Acetylcholine

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Rate limiting step in Ach formation

Uptake of Choline into neuron

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Drug that inhibit uptake of choline into neuron

Hemicholinum - decrease Ach action

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Drugs that inhibit entry of Ach in Vesicle

Vesamicol - decrease Ach action

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Drug that inhibit release of Ach from neuron

Botulinum toxin

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Ach in synapse is metabolized by

Acetylcholinesterase

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Cholinergic receptors are divided into

Nicotinic - Nn and Nm
Muscarinic - M1 to M5

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Location of Nicotinic receptors

Nn - Ganglion
Nm - Neuromuscular junction

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Location and Function of M1 receptors

Stomach - increase Hcl secretion

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Location and function of M2 receptors

Heart - decrease Heart rate and conduction

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Location and function of M3 receptors

Bronchus - Bronchoconstriction
Urinary bladder - Contracts detrusor muscle - increase urine outflow
Eye - Miosis (constriction of iris)
GIT - Increases motility - Diarrhea
Glands - increase secretions

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M3 and M4 receptors are mainly found in

Brain

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Cholinergic drugs can be divided into

Parasympathomimetics
Parasympatholytics

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Parasympathomimetics can be divided into

Directly acting
Indirectly acting or Achesterase inhibitors

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Drugs which are directly acting Parasympathomimetics

Acetylcholine
Bethanechol
Methacholine
Carbachol
Pilocarpine

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Bethanechol is used for treatment of

Atonic bladder or urinary retention

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Methacholine is used for

Myocardium - depress heart
Used in tachycardia or tachyarrythmia

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Pilocarpine is used in

Glaucoma particularly Angle closure glaucoma

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Carbachol is used in

Mixed action
Stimulates both muscarinic and nicotinic receptors

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Cevimeline is new approved drug for

Xerostomia (dry mouth) in Sjogren Syndrome

Acetylcholinesterase inhibitors are divided into

Reversible
Irreversible

Lipid Soluble reversible Achesterase inhibitors includes which drugs

Physostigmine
Gallantamine
Donepezil
Rivastigmine

Physostigmine can be used in

Angle closure glaucoma
DOC in Atropine Poisoning
Can be used in Alzheimer’s disease

Drug of choice in Alzheimer's disease

Tacrine - previously DOC S/E - very short acting and Hepatotoxic Gallantamine Donepezil Rivastigmine These drugs are preferred now

drugs for Alzheimer's disease

AchE inhibitors NMDA Blockers - Memantine Aducanumab

Water soluble reversible Achesterase inhibitors

Neostigmine Pyridostigmine Edrophonium

Which receptor needs optimal stimulation

Nm receptors

Drug or test used to differentiate between Myasthenia gravis and cholinergic crisis

Edrophonium Known as Edrophonium test or Tansilon test

Drugs used in treatment of Myasthenia gravis

Neostigmine Pyridostigmine

In Myasthenia gravis, Neostigmine is given with which drug

Neostigmine + Atropine to prevent muscarinic side effects

Neostigmine and Pyridostigmine can be used in which conditions

Myasthenia gravis Cobra bite For Reversal of Neuromuscular blockers after surgery Post operative paralytic ileus Post operative urinary retention

Irreversible Achesterase inhibitors includes

Organophosphates - Malathion, parathion, Sarin AND Carbamates - Carbryl, Propoxur

Symptoms seen in Organophosphates Posioning

Muscle weakness Deceased HR and BP Miosis (PIN POINT PUPIL) Increased secretions Bronchoconstriction Urination increases

Pin Point pupil can be seen in which Poisoning

O - Organophosphates and Carbamates, Opioids P- Phenol, Pontine hemorrhage

Symptoms only seen in OP Poisoning

Pin Point pupil + increased secretions combined

DOC in Organophosphates Posioning

Atropine iv repeated every 5 min until signs of atropinization

Signs of Atropinization are

Mydriasis - commonly seen Decreased secretions - most specific and reliable Tachycardia

Which sign of OP Poisoning can't be reversed by Atropine

Muscle weakness

Achesterase Reactivators are

OXIMES - Pralidoxime (PAM) Diacetyl Monoxime (DAM) Only for Organophosphates not Carbamates

Drugs which blocks M1 receptor

Pirenzepine Telenzipine - can be used to Peptic ulcer disease

Drug which can block all muscarinic receptors

Atropine

Anticholinergic drugs which blocks M3 receptors on Bronchus

Ipratropium Tiotropium - inhalational form

Anticholinergic drugs which blocks M3 receptors on bladder

Decreases contraction of bladder - can cause urinary retention Indicated for overactive bladder/urinary incontinence Drugs - Solefenacin Oxybutynin Flavoxate, Fesoterodine Tolterodine, Trospium Bladder - Darifenacin

Which anticholinergic drugs have maximum vasicoselective action

Solefenacin Darifenacin

Anticholinergic drugs that inhibit secretion by blocking M3 receptors

Glycopyrrolate - reduces secretion during anaesthesia Atropine

Anticholinergic drugs that acts on smooth muscles by blocking M3 receptors

Dicyclomine Hyoscine Oxybutynin Propantheline

Anticholinergic drugs effect on eye

Mydriasis - used in Fundoscopy Cycloplegia (Paralysis of ciliary muscles) - used in Refraction testing M3 receptors - Ciliary muscle contraction

Anticholinergic drugs used on eye

Atropine - longest acting drug on eye Homatropine Cyclopentolate Tropicamide - shortest acting cycloplegic drug

Anticholinergic drugs used for Motion sickness

Hyoscine (Scopolamine)

Drug of choice for Belladona and Dhatura Poisoning

Physostigmine