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Cholinergics
- 2. Nervous system Central nervous system (CNS) Peripheral nervous system 1. Autonomic nervous system 2. Somatic system, innervating skeletal muscle
- 3. Autonomic nervous system Most organs receive both sympathetic and parasympathetic innervation Functionally antagonistic Sympathetic /adrenergic system Parasympathetic/cholinergic system
- 5. Sites where the Ach acts as neurotransmitter NMJ All ganglia Postganglionic parasympathetic nerves Postganglionic sympathetic nerves of sweat glands Adrenal medulla
- 6. Sympathetic Parasympatheti c origin thoracolumbar craniosacral distribution wide Head, neck, sacral region ganglia Away from organ Close to organ Pre:Postganglioni c Fibre ratio 1:20-1:100 1:1-1:2 neurotransmitter Nor adrenaline(NA) Acetyl Choline(Ach) function Fight & Flight response Rest & digest response
- 7. Autonomic nerve CNS Preganglionic Nerve fibre Postganglionic Nerve fibre Ganglia Effector organ
- 8. Steps in neurotransmission Synthesis Storage Release Receptor action Termination
- 11. Choline TransporterCholine +AcetylC oA ACh ACh V A T Choline acetyl transferase Ca 2+ ACh Choline Acetate SNAP VAMP Choline esterase Hemicholinium Vescamicol Botulinum toxin A Botulinum toxin B & Beta bangarotoxin Black widow spider toxin Tetradotoxin Saxitoxin
- 12. Toxins Action Local anaesthetics,tetradotoxins(Puffer fish),saxitoxins(Gaunyaulax)(shell fish consumed red algal blooms) Block voltage-gated sodium channels Hemicholiniums Block uptake of choline Vesamicol Inhibits VAT Ω conotoxin(marine snails) Blocks nerve terminal calcium channels Alpha Latrotoxin(Black widow spider venom) Explosive transmitter release Alpha Bengarotoxin(cobra venom) Nm receptor antagonist Beta bengarotoxin(Krait venom) Inhibits release of acetylcholine Batrocotoxin(South African frog) Selective increase in permeability of sodium channels Scorpion toxin Persistant depolarisation by inactivation of Sodium channels
- 13. Cholinergic Receptors Muscarinic receptorsM1, M2, M3,M4,M5 Nicotinic receptors NM, NN
- 14. Rec epto r Site Action Nature Agonist Antagonist M1 CNS Ganglia Gastric parital cells CNS Learning & Memory Gastric glands gastric secretion G protein coupled (Gq) Oxotremorin e Pirenzepine Heart Presynaptic SA node heart rate AV node velocity of conduction Atria & Ventricles contractility Gi coupled Methacholin e Methoctrami ne M2 Smooth muscle including iris & ciliary muscles Glands Endothelial cells Visceral smooth muscle Contraction except urinary& intestinal sphinctors Exocrine glands Secretion Vascular endothelium: release NO vasodilation Ciliary muscle contraction Iris constriction of pupil Gq coupled Bethenechol Darifenacin M3 Ganglia Autonomic ganglia & Adrenal medulla Catecholamine release Ion channel DMPP Trimethapha n NN NMJ Neuromuscular junction Contraction of skeletal muscle Ion channel PTMA dTC ,Alpha Bangarotoxi n NM
- 15. Actions of ACh CVS HEART ↓ HR AV node - ↓ conduction Atria - ↓contraction BLOOD VESSELS Vasodilation M2 M3
- 16. Smooth muscle ↑contraction GIT - Tone & peristalisis in GIT ↑, Sphincters relax Abdominal cramps & evacuation of bowel Ureter peristalsis↑, Detrusor contracts, Bladder trigone & sphincter relax: Voiding Bronchospasm Eye Contraction of circular muscles of iris MIOSIS Contraction of ciliary muscles ↑outflow of aqueous humur↓ IOP M3 M3
- 17. GLANDS Secretion from all glands ↑ Salivation , Sweating, lacrimation, Gastric & Tracheobronchial secretion M3
- 18. NICOTINIC AUTONOMIC GANGLIA Sympathetic + Para sympathetic stimulation SKELETAL MUSCLES Contraction of muscle NN NM
- 19. Cholinergic drugs classification DIRECTLY ACTING Choline Esters Cholinomimetic Alkaloids INDIRECTLY ACTING Anti choline esterases Acetyl Choline Methacholine Carbachol Bethanechol Pilocarpine Muscarine Arecoline
- 20. Anti choline esterases Reversible Irreversible Carbamates Physostigmine Neostigmine Pyridostigmine Edrophonium Rivastigmine Donepezil Galantamine Acridine Tacrine Organophosphates Malathion Parathion Dyflos Echothiophate Diazinon Nerve gases Carbamates Propoxyfur Carbaryl
- 21. Choline ester Susceptibility To choline esterase Muscarinic action Nicotinic action Acetylcholine ++++ +++ +++ Methacholine + ++++ None Carbachol Negligible ++ +++ Bethanechol Negligible ++ None
- 22. Uses To reverse postoperative atony of bladder To expel gases from intestines prior to radiological examination To revert postoperative paralytic ileus of gut To treat salivary gland malfunction
- 23. Pilocarpine Source leaves of Pilocarpus Microphyllus Crosses BBB Too toxic for systemic use USES 1)3rd line drug - open angle glaucoma 2)To counteract mydriatics 3)Prevent adhesions in iridocyclitis by altering with mydriatics
- 24. Muscarine Amanita phalloides Amanita muscaria Mycetism-Mushroom poisoning Treatment-Atropine 1-2mg IM every 30 minutes
- 25. Arecoline Chief alkaloid of areca or betel nut
- 26. Anticholine esterases Drugs that inhibit choline esterase enzyme prevent the hydrolysis of Ach potentiates Ach action Classification
- 27. Anti choline esterases Reversible Irreversible Carbamates Physostigmine Neostigmine Pyridostigmine Edrophonium Rivastigmine Donepezil Galantamine Acridine Tacrine Organophosphates Malathion Parathion Dyflos Echothiophate Diazinon Nerve gases Carbamates Propoxyfur Carbaryl
- 28. Mechanism of action Choline esterase has 2 sites anionic site & esteratic site Carbamates bind to both A & E A E A E Carbamylated enzyme react slowly so hydrolysis of Ach is inhibited
- 29. OP bind to esteratic site only Phosphoylated enzyme react very slowly irreversibly inhibit Ach degradation Phosphorylated enzyme undergoes “aging” become totally resistant to hydrolysis A E
- 30. Actions LIPID SOLUBLE – ( Physostigmine & OP) Marked Muscarinic & CNS effects LIPID INSOLUBLE – ( Neostigmine) Effect on Skeletal muscle & stimulate ganglia Dont penetrate CNS & have no central effects Fasciculation & twitching
- 31. USES 1) Glaucoma ↑ tone of ciliary muscle outflow facility is ↑ Pilocarpine Physostigmine 2) To reverse the effects of mydriatics 3) MYASTHENIA GRAVIS Neostigmine Edrophonium (for diagnosis
- 32. 4)Post operative paralytic ileus/ urinary retention Neostigmine 5)Post operative decurarization Atropine (Block Muscarinic action) followed by Neostigmine 6)Cobra bite Neostigmine + Atropine 7) Belladona(Atropine) poisoning Physostigmine 8)Alzheimers disease Tacrine , Donepezil , Rivastigmine
- 33. OP poisoning lacrimation, salivation, sweating , miosis, blurring of vision, breathlessness, colic, involuntary defecation & urination cardiac arrhythmias Muscle fasciculations convulsions, coma & death ( RESPIRATORY FAILURE) Agricultural & household insecticide
- 34. TREATMENT Termination of further exposure to poison – fresh air, wash the skin with soap & water, gastric lavage Maintain patent airway Supportive measures Maintain BP, Hydration , control of convculsions diazepam
- 35. SPECIFIC ANTIDOTES 1. ATROPINE Highly effective in counteracting muscarinic symptoms Doesn’t reverse peripheral muscle paralysis (Nicotinic)
- 36. 2) OXIMES (Pralidoxime) OP A E A E OP OXIME Its oxime end reacts with Phosphorous atom attached to anionic site: Oxime Phosphonate diffuses away leaving reactivated Ach Esterase
- 37. Not effective in Carbamate poisoning because anionic site is not free CI Carbamate poisoning
Notas do Editor
- VAT-Vesicle Associated Transporter VAMP-Vesicle Associated Membrane Protein SNAPs-Synaptosomal Nerve Associated Protien