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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.

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

  5. Antimuscarinics Antimuscarinics Naturally occurring alkaloids synthetic atropine substitutes

  6. Antimuscarinics Muscarinic antagonists • Natural alkaloids • Drugs as : Atropine - Hyoscine • Esters of tropic acid and tertiary amines • Lipid soluble • Good oral absorption • Good distribution • Cross blood brain barrier (have CNS actions)

  7. Antimuscarinics Muscarinic antagonists Synthetic atropine substitutes Benztropine Homatropine Tropicamaide Pirenzepine Ipratropium Glycopyrrolate Oxybutynin

  8. Antimuscarinic drugs Mechanism of action • Reversible competitive blockade of muscarinic receptors. • Atropine can block all muscarinic receptors.

  9. Pharmacological effects of atropine CNS • Sedation • Antiemetic effect (block vomiting center) • antiparkinsonian effect (block basal ganglia). • Toxic dose: Hyperthermia - excitement-hallucination.

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

  11. 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 # glaucoma. •  Lacrimal secretion  sandy eye

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

  13. GIT • Relaxation of smooth muscles. •  GIT motility Antispasmodic effect. •  Sphincter contractions • Constipation Urinary Tract • Relaxation of smooth muscles of urinary bladder. • Sphincter contraction. • Urinary retention.

  14. Hyoscine (SCOPOLAMINE) What is difference between atropine and hyoscine? Hyoscine has Shorter duration of action More CNS depressant action Antiemetics action in motion sickness Can produce amnesia. Less CVS effect

  15. Uses of antimuscarinic drugs

  16. Adverse effects 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).

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

  18. Can antimuscarinic drugs reverse the action of neostigmine on skeletal muscles?

  19. SUMMARY • Antimuscarinics reverse action of cholinomimetics on muscarinic receptors. • Are useful in many applications including intestinal spasm, constipation, urinary retention, vomiting, parkinsonism, asthma and peptic ulcer. • Are contraindicated in constipation, Prostate hypertrophy, tachycardia and glaucoma.

  20. Thank youQuestions ?

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