690 likes | 1.78k Views
Cholinergic drugs. Nervous system. CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEMS Sensory fiber motor fiber involuntary voluntary sympathetic parasympathetic. function.
E N D
Nervous system • CENTRAL NERVOUS SYSTEM • PERIPHERAL NERVOUS SYSTEMS • Sensory fiber motor fiber • involuntary voluntary • sympathetic parasympathetic
function • Sympathetic and parasympathetic are complemantary • Composition: pre,ganglion and post • Chemicals are Ach and NA
Cholinergic drugs • Drugs produce similar effects to acetylcholine
Classification • Direct cholinergic agents • Indirect • Cholinestrase reactivator
Effects of acetylcholine • Muscarinic effects • Contaraction of smooth muscle • Peripheral vasodilation • Increase secretion of saliva, exocrine • Dcrease the contraction of the heart B. Nicotinic • Stimulation of skeletal muscle tone
Trans acetylcholine active on muscarinic and nicotinic receptors
A. Direct cholinergic agents Mode of action Cholinomimetic alkaloid Choline esters Pilocarpine Methacholine Carbachol [Cholinomimetics & parasympathomimetics]
SAR Acetyl choline
Metacholine • CH3 on beta carbon increase muscarinic • Long duration • Uses: Mythenia gravis, paroxysmal tachycardia
Carbachol • Long duration • Uses: glucoma • Synthesis
Bethanicol • Bioisoster of methacholine • Long duration • Mainly muscarinic • Uses:abdominal distention,urinary distention
2. Cholinomimetic alkaloid • pilocarpine Uses: glucoma, antagonises mydriatics
cevimeline • For treatment of dry mouth in Sjogren’s syndrome • Similar to pilocarpin
B.Indirect acting [anticholinesterase] Organophosphorus Carbamates Physostigmine Neostigmine methyl sulphate Pyridostigmine Neostigmine bromide(prostigmin) Edrophonium
Physostigmine acts by interfering with the metabolism of acetylcholine. It is an inhibitor of acetylcholinesterase, the enzyme responsible for the breakdown of acetylcholine in the synaptic cleft of the neuromuscular junction. It indirectly stimulates both nicotinic and muscarinic receptors. (Find the structure and uses).
Neostigmine methyl sulphate • Uses • Contraindication Bradycardia, cardiac disease, hypotension, parkinsonism.
Synthesis • Uses: Mysthenia gravis
Edrophonium Chloride Short and rapid-acting cholinergic drug. Uses:myasthenia gravis , emergency treatment (short action) Side effects: bradycardiaa, hypotension,increase saliva
Cholinesterase reactivators 2-[(Hydroxyimino)methyl]-1-methylpyridinium chloride
Cholinergic blocking agents[Anticholinergic] • Act at different sites Postganglionic of parasympathetic (Antimuscurinic) At ganglionia of sympathetic and parasympathetic (ganglion blockers) Neuromuscular junction of voluntry system (neuromuscular blocking agents)
I. Antimuscarinics[similar to Ach & alkaloid] • There effects will be : • Mydriatic • Antispasmodic • antisecretory
Antimuscarinics similar to Acetyl choline 5 A Antimuscarinic:aminoalcohol,aminoamides,papaverine derivatives. Aminoalcohols:esters,ethers,carbamates. Esters:solaneceous alk.,synthetic analouges,esters of other alc.
2. Alkaloid antimuscarinics • Atropine, Hyoscin Uses of Antimuscarinics: Antispasmodic Antisecretory Antiparkinsonism mydriatics
Esters of other aminoalcohol • Cyclopentolate • Uses: mydriatic ,cycloplegic
Aminoalcohol ethers • Orphenadrine • Uses: Antihistaminic,antiparki-nsonism. N,N-dimethyl-2-(phenyl(o-tolyl)methoxy)ethanamine
Oxybutynin • used to relieve urinary and bladder difficulties, including frequent urination and inability to control urination • Homework : find the structure and mechanism of action
Papaverine and related compounds. Vasodilator relax smooth muscle.(GIT,bronchi,uretures,biliary system).
Trihexyphenidyl • Uses • Parkinson’s disease
Ipratropium bromide • Uses Bronchodilator
Ganglionic blocking agent • Hexamethonium
Neuromuscular bloking agents • Decamethonium bromide • Assay :volhard