PARASYMPATHOMIMATICS (M.PHARM) 1st sem.pptx

TOPIC- PARASYMPATHOMIMATICS (ADVANCE PHARMACOLOGY) M.PHARM 1ST SEMESTER (PHARMACOLOGY)

1. A Presentation on the Topic PARASYMPATHOMIMATICS Advance Pharmacology (MPL102T) Presented by Mohd. Khalid Raza M.Pharm Sem 1st DEPARTMENT OF PHARMACOLOGY

2. Content Nervous system Cholinergic receptors Neurotransmitter Pharmacological action of acetylcholine Classification of Parasympathomimetic drugs References 2

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5. Nicotinic receptor Divided into two types Nn and Nm. Activation of these receptor directly open ion channel and causes depolarization of the membrane. NM-Contraction of Neuromuscular junction (skeletal muscle). Nn- Present on Autonomic ganglia, Adrenal medulla. Muscuranic receptors G- Protein coupled receptor. Divided into five types- M1, M2, M3, M4, M5. 5

6. Neurotransmitter Acetylcholine (Ach) is is the principal neurotransmitter in the cholinergic system. Acetylcholine is synthesized locally in cholinergic nerve ending. Acetylcholine is quaternary ammonium compounds and is rapidly hydrolysed by cholinesterases. hence no therapeutic application. 6

7. Pharmacological action of acetylcholine [A] Muscarinic action - (1) Cardiovascular system - 7

8. (2) Smooth muscles 8

9. [B] Nicotinic action (1) Autonomic ganglia - Both parasympathetic and sympathetic ganglia are stimulated by ACh through the stimulation of NN receptor. (2) Neuromuscular Juction - ACh stimulates skeletal muscle contraction by action on NM receptor. 9

10. Classification of Parasympathomimetic drugs 10

11. Directly acting parasympathomimetic drugs Natural alkoloids - Acetylcholine, Muscarine, Nicotine, Pilocarpine, Arecoline. Synthetic derivative - Methacholine, Carbachol, Bethanechol. Pilocarpine - Pupil - M3 receptor Obtained from Pilocarpus plant, mainly used for glaucoma. Bethanechol - Bladder - M3 receptor Used for treatment of urinary retention Methacholine - Myocardium - M2 receptor Used for tachycardia Carbachol - Common action - Nicotinic, Muscarinic Muscarine – It is an active ingredient of poisonous mushroom Antidote - Thiotic acid 11

12. Indirectly acting parasympathomimetric drugs These drugs act by inhibiting the enzyme acetylcholineesterase , thus prolonging the action of ACh . These drugs are also called as anticholineesterase . Anticholinesterase may be reversible or irreversible. Reversible– Physostigmine, Neostigmine, Pyridostigmine, Endrophonium , Tacrine. Irreversible– Dyflos , Echothiophate , Parathion, Diazinon, Tabun, Carbaryl. 12

13. Physostigmine - (Eserine) It is an alkaloids obtained from Physostigma Venenosum . Lipid soluble tertiary amine derivative. In eye causes miosis so used in glaucoma. Drug of choice for Atropine poisoning. Neostigmine It is a synthetic anticholinesterase agent. Used in postoperative retention, myasthenia gravis. Edrophonium Quaternany ammonium compound. Suitable as a diagnostic agent for myasthenia gravis. 13

14. Tacrine Drug of choice for Alzheimer’s disease. Now prefered drug are - Donepezil, Rivastigmine, Galantamine. Irreversible Highly lipids soluble, used as insectisides . Organophosphate - Malathion, Parathion, Ecothiophate , Dyflos . Carbamate - Carbaryl and Propoxur. Except Ecothiophate - these are not used therapeutically. Antidote – Atropine 14

15.   References Tripathi, K. D. 2018. Essentials of Medical Pharmacology. 8th ed. New Delhi, India: Jaypee Brothers Medical. https://www.slideshare.net/SanthoshRK3/parasympathomimetic 15

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