Uploaded byIAU Dent
3.cholinergic drugs
This document discusses the autonomic nervous system and cholinergic transmission. It describes how drugs can have parasympathomimetic or parasympatholytic effects by stimulating or opposing muscarinic receptors. There are three main types of muscarinic receptors (M1, M2, M3) located throughout the body. Drugs that stimulate muscarinic receptors can be direct acting parasympathomimetics or indirect acting via inhibiting acetylcholinesterase. Common cholinergic drugs and their effects/indications are also outlined.
More Related Content
Similar to 3.cholinergic drugs
3.cholinergic drugs
- 2. Introduction Organization of thenervous system Lippincott’s pharmacology 4th edition
- 3. Drugs Act onAutonomic nervous system Drugs that produce Parasympathetic like actions = Parasympathomimetics = Cholinergics Drugs that oppose Parasympathetic = Parasympatholytic = Anticholinergics Drugs that produce sympathetic like action = Sympathomimetics = Adrenergics Drugs that oppose sympathetic = Sympatholytics = Antiadrenergics
- 4.
- 5. Cholinoceptors • Muscarinic receptors:3 subtypes are well defined pharmalogically M1, M2 M3 found on ganglia of the peripheral nervous system and on the autonomic effector organs, such as the heart, smooth muscle, brain, and exocrine glands • Nicotinic receptors (N) present in autonomic ganglia adrenal medulla neuromuscular junction
- 6. Drugs that stimulatemuscarinic receptors Direct Parasympathomimetics Indirect Parasympathomimetics (Anti-cholinesterases) Direct Parasympathomimetics: They stimulate the muscarinic receptors directly. Indirect Parasympathomimetics (Anti-cholinesterases): They inhibit cholinesterase enzyme leading to accumulation of endogenous acetylcholine at both muscarinic and nicotinic receptors Mechanism of action
- 8. Pharmacological actions ofCholinergics Effector organs Effects Eye Myosis Accommodation Reduction of intraocular pressure (IOP) Increase lacrymation. Heart ↓ heart rate ↓ force of contraction Slow conduction Blood vessels Constriction of coronary arteries Stomach and Intestine ↑ motility and secretion Urinary bladder Relaxation of sphincters and contraction of bladder wall Respiratory system Constriction of bronchi increased bronchial secretions Exocriene glands Stimulate all e.g. sweating, salivation and lacrymation.
- 9. Direct cholinergic agentsAcetyl-choline isIt is a natural direct parasympathomimetic. stimulates directly both muscarinic & nicotinic receptors important physiologically, it is not used clinically because its actions are very brief because of rapid hydrolysis Methacholine more selective on cardiovascular system .Weak nicotinic effect. Carbachol : has muscarinic and nicotinic but it is mainly selective on EYE, gastrointestinal tract and urinary tract Bethanichol Actions: No nicotinic action, but only muscarinic action which is mainly selective on gastrointestinal tract , and urinary system. Pilocarpine Direct muscarinic agonist specific on eye and secretions . Very weak nicotinic action
- 10. Reversible anticholinesterases Physostigmine has muscarinicaction most specific on eye and CNS stimulation Neostigmine It produces both nicotinic and muscarinic actions but it is more active on the nicotinic receptors of the N-M junction. Its muscarinic actions are more specific on the gastrointestinal and urinary tracts. No CNS action
- 11. Generic name Indication Methacholineparoxysmal atrial tachycardia and peripheral vascular disease Carbachol Glucoma Post-operative paralytic ileus Post- operative retention of urine Bethanechol Post-operative paralytic ileus Post- operative retention of urine Pilocarpine Glucoma physostigmine Glucoma Anti-cholinergic poisoning Neostigmin Myasthenia gravis Reversal of neuromuscular blockade Urine retention Cholinergic agents indications
- 12. cholinergic agents Adverse effects •Muscarinic: ◆ Miosis, lacrymation, salivation, sweating ◆ Urgency and spontaneous micturition ◆ Bronchospasm and increased bronchial secretion. ◆ Bradycardia and hypotension. ◆ Colic, vomiting, diarrhea, hyperacidity & peptic ulcer • Nicotinic: skeletal muscle twitches followed by paralysis Contraindication • Bronchial asthma • Peptic ulcer • Coronary insufficiency • Thyrotoxicosis • Mechanical obstruction of the GIT and urinary bladder
- 13.