1 / 36

Drugs Affecting the Parasympathetic Nervous System

Drugs Affecting the Parasympathetic Nervous System. Drugs Affecting the Parasympathetic Nervous System. Parasympathetic Nervous System Neurotransmitter is ACH The receptors are called cholinergic receptors.

jacob
Download Presentation

Drugs Affecting the Parasympathetic Nervous System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Drugs Affecting the Parasympathetic Nervous System

  2. Drugs Affecting the Parasympathetic Nervous System Parasympathetic Nervous System • Neurotransmitter is ACH • The receptors are called cholinergic receptors. • Drugs that bind to cholinergic receptors and produced effects similar to ACH are referred to as cholinergic drugs.

  3. Drugs Affecting the Parasympathetic Nervous System ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH Acetylcholinesterase

  4. Drugs Affecting the Parasympathetic Nervous System Receptors Muscarinic Receptors Nicotinic Receptors N-1 N-2

  5. Drugs Affecting the Parasympathetic Nervous System Nicotinic Receptors Nicotinic-II Receptors Nicotinic-I Receptors Found at ganglions of Sympathetic and Parasympathetic Post- ganglionic fibers Found at Neuromuscular junction of Skeletal muscles.

  6. Drugs Affecting the Parasympathetic Nervous System Ganglion, Nicotinic I receptor Sympathetic Fibers Post-ganglionic Fiber Pre-ganglionic Fiber Adrenergic Receptor Ganglion, Nicotinic I receptor Parasympathetic Fibers Pre-ganglionic Fiber Post-ganglionic Fiber Muscarinic Receptors Somatic Fibers Nicotinic II Receptors

  7. Drugs Affecting the Parasympathetic Nervous System Nicotine • Alkaloid obtained from tobacco. • Stimulate the NI receptors at low doses. • Block the NII receptors at high doses.

  8. Drugs Affecting the Parasympathetic Nervous System Nicotinic I Drugs Ganglionic Stimulants Ganglionic Blockers

  9. Drugs Affecting the Parasympathetic Nervous System Muscarinic Receptors • Found at the parasympathetic postganglionic nerve endings • Drugs that act like ACH at these receptors are referred to as cholinergic or muscarinic drugs. • Drugs that block ACH at the muscarinic receptors are referred to as anticholinergic or antimuscarinic drugs.

  10. Drugs Affecting the Parasympathetic Nervous System Parasympathetic Drugs Cholinergic Drugs Anti-cholinergic Drugs

  11. Drugs Affecting the Parasympathetic Nervous System Cholinergic Drugs Direct Acting Cholinergic Drugs Indirect Acting Cholinergic Drugs

  12. Drugs Affecting the Parasympathetic Nervous System Direct Acting Cholinergic Drugs • Bind to muscarinic receptors. • Produces ACH like effect. • Slowly inactivated by acetylcholinesterase.

  13. Drugs Affecting the Parasympathetic Nervous System Pharmocological Effects • Increase GI secretion and motility • Increase in genitourinary activity. • Bronchoconstriction

  14. Drugs Affecting the Parasympathetic Nervous System Pharmocological Effects • Miosis • Vasodilatation (lower BP) • Decrease heart rate.

  15. Drugs Affecting the Parasympathetic Nervous System

  16. Drugs Affecting the Parasympathetic Nervous System Indirect Acting Cholinergic Drugs (Anticholinesterases) Irreversible Inhibitors Reversible Inhibitors

  17. Drugs Affecting the Parasympathetic Nervous System ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH ACH Acetylcholinesterase Anticholinesterases

  18. Drugs Affecting the Parasympathetic Nervous System Reversible Inhibitors • Blocks cholinergic and nicotinic receptors. • Use in the diagnosis and treatment of myasthenia gravis.

  19. Drugs Affecting the Parasympathetic Nervous System Irreversible Inhibitors • Derivatives of organophosphate compounds. • Widely used as insecticides, pesticides and chemical warfare agents. • Long duration of action

  20. Drugs Affecting the Parasympathetic Nervous System Clinical Use • Topical use in glaucoma • Treatment of myasthenia gravis • Treatment of urinary retention and intestinal stasis

  21. Drugs Affecting the Parasympathetic Nervous System Clinical Use • Treatment of Alzheimer’s disease. • Antidote to skeletal muscle blockers. • Antidotes to anticholinergic drug poisoning.

  22. Drugs Affecting the Parasympathetic Nervous System Indirect-Acting Cholinergic Drug Irreversible Isoflurophate Reversible Ambenonium Edrophonium Neostigmine Physostigmine Pyridostigmine

  23. Drugs Affecting the Parasympathetic Nervous System Adverse and Toxic Effect • Nausea • Vomiting • Diarrhea • Blurred vision

  24. Drugs Affecting the Parasympathetic Nervous System Adverse and Toxic Effect • Excessive sweating • Muscular tremors • Bronchoconstriction • Bradycardia

  25. Drugs Affecting the Parasympathetic Nervous System Adverse and Toxic Effect • Hypotension • Mucular paralysis • Respiratory arrest

  26. Drugs Affecting the Parasympathetic Nervous System Cholinergic Crisis • Excessive drug dosage in patients with myasthenia gravis. • High concentration of ACH causes excessive stimulation of the muscarinic receptors. • High concentration of ACH causes blockade of nicotinic receptor.

  27. Drugs Affecting the Parasympathetic Nervous System Treatment • Stop anticholinesterase drug administration. • Give atropine to block the effect of excess muscarinic stimulation

  28. Drugs Affecting the Parasympathetic Nervous System Cholinergic Crisis • Excessive exposure to sprays containing derivatives of irreversible anticholinesterase. • High concentration of ACH causes excessive stimulation of the muscarinic receptors. • High concentration of ACH causes blockade of nicotinic receptor.

  29. Drugs Affecting the Parasympathetic Nervous System Treatment • Remove person from the exposure. • Give Pralidoxime to reactivate the anticholinesterase enzyme. • Give atropine to block the effect of excess muscarinic stimulation

  30. Drugs Affecting the Parasympathetic Nervous System Anticholinergic Drugs • Binds to muscarinic receptors. • Act by competitive antagonism of ACH. • Prototype drugs: Belladonna alkaloids, atropine and scopolamine

  31. Drugs Affecting the Parasympathetic Nervous System Pharmacological Action • Increase heart rate. • Increase the secretions of the respiratory tract and may cause bronchoconstriction. • Reduce salivary and GI tract. • Inhibit urinary peristalsis and voiding of urine.

  32. Drugs Affecting the Parasympathetic Nervous System Pharmacological Action • Depressant effects on the CNS causing drowsiness and sedation. • At high doses cause both stimulation and depression of the CNS • At toxic doses excitation, delirium, hallucination and profound CNS depression leading to respiratory arrest and death.

  33. Drugs Affecting the Parasympathetic Nervous System Ocular Effect • Mydriasis • Cycloplegia • Increases Intraocular pressure.

  34. Drugs Affecting the Parasympathetic Nervous System Adverse and Toxic Effect • Cause by excessive blockage of the Parasympathetic Nervous System. • Dry mouth. • Visual disturbances • Urinary retention • Constipation.

  35. Drugs Affecting the Parasympathetic Nervous System Adverse and Toxic Effect • Dryness of the skin • Flushing • Hyperpyrexia • CNS stimulation and depression

  36. Drugs Affecting the Parasympathetic Nervous System Anticholinergic Drugs Semisynthetic Drug Homatropine Synthetic Drugs Diclyclomine Isopropamide Propantheline Methantheline Belladonna Alkaloids Atropine Scopolamine Hyoscyamine

More Related