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ANTICHOLINERGIC DRUGS

ANTICHOLINERGIC DRUGS. Anticholinergic drugs. What students should know: Student should be able to : Describe Kinetics of muscarinic antagonists The effects of atropine on the major organ systems. To list the clinical uses of muscarinic antagonists .

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ANTICHOLINERGIC DRUGS

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  1. ANTICHOLINERGIC DRUGS

  2. Anticholinergic drugs • What students should know: • Student should be able to : • Describe Kinetics of muscarinic antagonists • The effects of atropine on the major organ systems. • To list the clinical uses of muscarinic antagonists. • To know adverse effects& contraindications of anticholinergic • drugs. • To identify at least one antimuscarinic agent for each of the • following special uses:mydriasis, cyclopedia, peptic ulcer & • parkinsonism.

  3. Anticholinergic drugs are drugs that block cholinergic receptors. Two types are available 1. Nicotinic blockers (antinicotinics). Ganglionic blockers (not used Clinically Why?) Neuromuscular blockers (Skeletal Muscle Relaxants) 2. Muscarinic blockers (antimuscarinics) Naturally occurring alkaloids (e.g: Atropine) Synthetic atropine substitutes.

  4. Anticholinergic drugs Antimuscarinics (Parasympatholytics) Antinicotinics Ganglionic blockers Neuromuscular blockers Naturally occurring alkaloids synthetic atropine substitutes

  5. Muscarinic antagonists Natural alkaloids • History (Thousants of years) • Atropine (Hyoscyamine) • Hyoscine (scopolamine) • Esters of tropic acid and tertiary amines • Lipid soluble • Good oral absorption • Good distribution • Cross blood brain barrier (have CNS actions)

  6. Muscarinic antagonists Synthetic atropine substitutes Tertiary amines Lipid soluble central actions Benztropine Homatropine Tropicamaide Pirenzepine Oxybutynin Quaternary amines Polar, water soluble No CNS effects Ipratropium Glycopyrrolate N+

  7. Muscarinic antagonists Quaternary amines

  8. Antimuscarinic drugs

  9. Antimuscarinic drugs Mechanism of action • Reversible competitive blockade of muscarinic receptors. Can antimuscarinic drugs reverse the action of Ach on skeletal muscles?

  10. Pharmacological Effects of Antimuscarinic Drugs CNS • CNS depression • Antiemetic effect (block vomiting center) • antiparkinsonian effect (block ACH at basal ganglia). • Toxic dose: Hyperthermia - excitement-hallucination.

  11. Cardiovascular system (CVS) • Tachycardia (increase heart rate) • AV conduction ( + ve dromotropic effect) • Therapeutic dose:  Vasodilatation induced by cholinomimetics. • Toxic dose: Cutaneous vasodilatation  (atropine flush). Respiratory system • Bronchial Relaxation (bronchodilator) •  Bronchial secretion  viscosity

  12. Eye • Passive mydriasis due to paralysis of circular muscle • Cycloplegia (loss of near accommodation) due to paralysis of ciliary muscle. • Loss of light reflex. • Increase I.O.P (worsens glaucoma). •  Lacrimal secretion  sandy eye

  13. Secretions Salivary secretion  ( Dry mouth ).  Sweating  Dry skin  Fever in infants and children.  Bronchial secretion   Viscosity Lacrimal secretion  Sandy eye

  14. GIT • Relaxation of smooth muscles. •  GIT motility  Antispasmodic effect. •  Sphincter contractions • Constipation Urinary Tract • Relaxation of smooth muscles of ureters. • Sphincter contraction. • Urinary retention (worsens prostate hypertrophy).

  15. Hyoscine (SCOPOLAMINE) What is difference between atropine and hyoscine? Hyoscine has Shorter duration of action More CNS depressant action Antiemetics action in motion sickness Amnesic action. Less CVS effect Can you put a question for exam?

  16. Uses of antimuscarinic drugs

  17. Adverse effects (usually can be observed with antidepressant s and antipsychotics) • Eye: Blurred vision – Mydriasis • CVS: Tachycardia - Atropine flush • GUT: Urinary retention • GIT: Constipation, paralytic ileus • Secretions: Dryness of mouth , Sandy eye • Increased body temperature. • CNS: sedation, hallucination, excitation (Toxic dose). • Treatment • Gastric lavage. • Anticonvulsant. • Cooling blanket. • Antidote: Physostigmine ( IV slowly).

  18. Treatment of anticholinergic Toxicities • Gastric lavage. • Anticonvulsant. • Cooling blanket. • Antidote: Physostigmine ( IV slowly).

  19. Contraindications • Glaucoma (angle closure glaucoma) • Tachycardia • Prostate hypertrophy in old patients. • Constipation, paralytic ileus, intestinal obstruction. • Children in case of atropine

  20. Thank youQuestions ?

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