Paper I
2022 May (Supplementary) (2010 Scheme) · 40 marks · 120 min

Question

Therapeutic uses and adverse effects of morphine and its congeners

Q53 marksShort Notes

Answer

Morphine congeners share the parent’s mu-receptor agonist action, with individual agents suited to particular clinical settings.

Therapeutic uses

  • Morphine — severe acute pain (post-operative, MI), chronic cancer pain, acute pulmonary edema (preload reduction)
  • Pethidine — obstetric analgesia (less neonatal respiratory depression, shorter action), used for procedural sedation
  • Fentanyl — anesthesia adjunct (rapid onset, short duration), transdermal patch for chronic cancer pain
  • Codeine — mild-moderate pain, antitussive
  • Methadone — opioid dependence substitution therapy, chronic pain (long half-life)
  • Diphenoxylate/Loperamide — antidiarrheal (gut-selective at normal doses)

Adverse effects

  • Respiratory depression — the most dangerous, shared by all mu-agonists
  • Constipation, nausea and vomiting, sedation
  • Tolerance and physical/psychological dependence with repeated use
  • Pethidine specifically — atropine-like effects (dry mouth, tachycardia) from its weak antimuscarinic action, and a risk of serotonin-syndrome-like toxicity with MAO inhibitors
  • Fentanyl — chest-wall rigidity with rapid IV injection

Other Years Asked


Revise MBBS
Preview