Cholinergic & Anticholinergics Flashcards
What are the different type of Cholinergic receptors and which system do they represent?
Muscarinic
M1: stomach CNS, impt in nausea and vomiting pathways
M2: heart,CNS
M3: lungs, glands, GI tract, CNS, eyes
M4,M5: CNS
Nicotinic
N1 or Nm: skeletal muscle
N2 or Nn: ganglion,CNS
What are the common adverse effects of cholinergic agonists
-Diarrhoea
-Diaphoresis
-Miosis
-Nausea
-Urinary urgency
What are some general contraindications of cholinergic drugs?
Asthma
Peptic ulcer- cholinergic drugs can enhance gastric acid secretion
What substance is a quaternary ammonium and does not cross membranes or BBB?
Acetylcholine
Lists the uses and AE of Pilocarpine
M3 muscarinic receptor agonist;
use in Glaucoma and Xerostomia (dry mouth)
AE: CI in Asthma, COPD, sweating and burring vision
List the uses and AE of Bethanechol
M3 muscarinic receptor agonist;
treatment for gastric atony after vagotomy (management of peptic ulcer), treatment of urinary retention (induce urination)
AE: CI in Asthma, nausea, vomiting, miosis
List the uses and AE of Nicotine.
Nm and Nn nicotinic Ach receptor agonist;
aid to smoking cessation
AE: Peripheral vasoconstriction (sympathetic); Gut hypermobility (parasympathetic) Both sympathetic and parasympathetic is activated; different system has different priority
List the uses and AE of Varenicline
Partial nicotinic agonist
aid to smoking cessation
associated with psychiatric symptoms (suicidal ideation)
How do indirect cholinergic drugs work?
They inhibit the action of acetylcholinesterase (AChE) which breakdowns Ach –> increasing Availability of acetylcholine.
List the uses and AE of Donepezil
AChE inhibitor
crosses BBB easily; use in Alzheimer’s disease (promotes modest cognitive improvement)
AE: nausea, vomiting and other common cholinergic side effects
List the uses and AE of Physostigmine
AChE inhibitor
crosses BBB easily; use as antidote for atropine poisoning
AE: nausea, vomiting and other common cholinergic side effects
Describe the pathophysiology of myasthenia gravis.
Myasthenia gravis is an autoimmune disease in which antibodies attack the Nm nAChRs at the neuromuscular junctions. Muscles cannot contract due to the lack of Ach Signal due to destroyed receptors
List the uses and AE of Neostigmine
AChE inhibitor
treatment for Myasthenia gravis; reversal of nondepolarizing neuromuscular blockade
AE: poor CSF penetration so no nausea; diarrhea, seating and urinary urgency
List the AE and antidote of Sarin
Organophosphate agent; suicide AChE inhibitor (effects are very long lasting)
Acute poisoning:
SLUD: Salivation, Lacrimation, Urination, Defecation
Also: Coma, Seizure, nausea, Bradycardia
Antidote: Cholinesterase regenerator (Pralidoxime)
mACh receptor block (atropine)
What must be taken into account when administering pralidoxime for acute Sarin poisoning?
Must be administered within a few hours before “ageing” (further chemical reaction that make the inhibition irreversible.
What are some adverse effects of muscarinic antagonism?
Urinary retention, constipation, mydriasis (dilation of eyes), confusion, blurred vision
List the type , uses and AE of Atropine.***
Nonselective muscarinic Ach receptor antagonist.
Uses: treatment of bradycardia (increase heart rate), treatment of anticholinesterase overdose, GI antimotility to treat diarrhea.
AE: “red as a beet, blind as a bat, dry as a bone, hot as a hare, mad as a hatter”: superficial vasodilation, blurred vision, decreased secretions, hyperthermia, hallucinations
CI in Narrow-angle glaucoma (increase intraocular pressure)
List the type, uses and AE of Benzatropine
Nonselective M receptor antagonist
Crosses BBB and has stronger CNS effect
Uses: Parkinson’s disease: second or third line therapy
AE: hyperthermia due to decrease sweat, glaucoma, urinary retention, dry mouth, constipation, hallucination, sedation
CI in Narrow-angle glaucoma (increase intraocular pressure)
List the type, uses and AE of Scopolamine (hyoscine)
Nonselective muscarinic Ach receptor antagonist.
Uses: motion sickness, adjunct for anaesthesia, urinary incontinence
AE: Dry mouth, urinary retention , sedation , glaucoma
CI in Narrow-angle glaucoma (increase intraocular pressure)
List the type, uses and AE of Ipratropium
Nonselective muscarinic Ach receptor antagonist.
M3 Effect: Decrease bronchoconstriction and bronchial secretion
Uses: COPD and asthma
AE: decrease GI motility , tachy, mydriasis
CI in Narrow-angle glaucoma (increase intraocular pressure)
List the type, uses and AE of Oxybutynin
Nonselective muscarinic Ach receptor antagonist.
M3 Effect: relax smooth muscle walls, increase sphincter tone and decrease secretions
Uses: urinary incontinence
AE: decrease GI motility , tachy, mydriasis
CI in Narrow-angle glaucoma (increase intraocular pressure), Ci in pyloric obstruction, retentive bladder (cannot empty all your urine)
What happens when u give nicotine in high doses?
Induce Depolarizing blockade; induce medullary depression as all ganglionic nicotinic receptor are blocked
What indirect anticholinergic drug is a depolarizing neuromuscular blocking agent? How does it work and what does it cause?
Succinylcholine
Causes twitching initially ,followed by flaccid paralysis
use for paralysis in surgical procedures.
* cannot be reversed by tetanic stimulation or cholinesterase inhibitor
What direct anticholinergic drug is a non-depolarizing neuromuscular blocking agent? How does it work and what does it cause?
Pancuronium
Competitive antagonist of Nm Nicotinic acetylcholine receptor
- non depolarizing blockade results in skeletal muscle paralysis
Uses: induction of paralysis for surg
AD: histamine release
* can be reversed by tetanic stimulation or cholinesterase inhibitor
What indirect anticholinergic drug is a inhibitor of vesicular exocytosis? How does it work and what does it cause?
Botulinum Toxin (BOTOX)
Mechanism: prevent exocytosis of ACh containing synaptic vescles
Uses: paralysis certain muscle
Side effect: allergic reaction
