Paper I
2021 February (Supplementary) (2010 Scheme) · 40 marks · 120 min

Question

Classify anticholinergic drugs. Describe the pharmacological actions, therapeutic uses and contraindications of atropine. (2+2+1+1)

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Answer

Classification of anticholinergic (antimuscarinic) drugs

  • Natural alkaloids: Atropine, Hyoscine
  • Semisynthetic: Ipratropium, Tiotropium
  • Synthetic: Glycopyrrolate, Trihexyphenidyl (used centrally in Parkinsonism), Dicyclomine (antispasmodic)

Pharmacological actions of atropine

  • Antisecretory (reduces salivary, bronchial, sweat gland secretions)
  • Mydriasis and cycloplegia
  • Tachycardia (blocks vagal tone)
  • Bronchodilatation
  • Reduced GI/GU smooth muscle motility (antispasmodic)
  • CNS: at high doses, excitement/delirium

Therapeutic uses

  • Preanaesthetic medication
  • Antidote for organophosphorus/anticholinesterase poisoning
  • Treatment of bradycardia/AV block
  • Mydriatic/cycloplegic for ophthalmic examination
  • Antispasmodic (GI/renal/biliary colic)

Contraindications

  • Narrow-angle glaucoma
  • Prostatic hypertrophy (urinary retention)
  • Tachyarrhythmias
  • Paralytic ileus/GI obstruction

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