Cholinergic System Flashcards
PNS originates from
Craniosacral outflow
Cranial nerves - ii, vii, ix, x
Sacral - S2,3,4
Neurotransmitter in PNS
Acetylcholine
Rate limiting step in Ach formation
Uptake of Choline into neuron
Drug that inhibit uptake of choline into neuron
Hemicholinum - decrease Ach action
Drugs that inhibit entry of Ach in Vesicle
Vesamicol - decrease Ach action
Drug that inhibit release of Ach from neuron
Botulinum toxin
Ach in synapse is metabolized by
Acetylcholinesterase
Cholinergic receptors are divided into
Nicotinic - Nn and Nm
Muscarinic - M1 to M5
Location of Nicotinic receptors
Nn - Ganglion
Nm - Neuromuscular junction
Location and Function of M1 receptors
Stomach - increase Hcl secretion
Location and function of M2 receptors
Heart - decrease Heart rate and conduction
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
M3 and M4 receptors are mainly found in
Brain
Cholinergic drugs can be divided into
Parasympathomimetics
Parasympatholytics
Parasympathomimetics can be divided into
Directly acting
Indirectly acting or Achesterase inhibitors
Drugs which are directly acting Parasympathomimetics
Acetylcholine
Bethanechol
Methacholine
Carbachol
Pilocarpine
Bethanechol is used for treatment of
Atonic bladder or urinary retention
Methacholine is used for
Myocardium - depress heart
Used in tachycardia or tachyarrythmia
Pilocarpine is used in
Glaucoma particularly Angle closure glaucoma
Carbachol is used in
Mixed action
Stimulates both muscarinic and nicotinic receptors
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
