Paper I
2024 March (Supplementary) (2019 Scheme) · 100 marks · 180 min

Question

(

  • (a) Neostigmine. (
  • (b) Ondansetron.
Q78 marksShort Essays

Answer

a) Neostigmine A reversible anticholinesterase, quaternary (does not cross the blood-brain barrier), with prominent direct skeletal-muscle action. MOA: prolongs the action of endogenous acetylcholine at cholinergic synapses by reversibly inhibiting acetylcholinesterase. Uses: myasthenia gravis (first-line symptomatic therapy), reversal of non-depolarizing neuromuscular blockade (with atropine, to block accompanying muscarinic effects), postoperative urinary retention and paralytic ileus. Adverse effects: muscarinic overactivity (salivation, sweating, bradycardia, bronchospasm, GI cramps/diarrhea), cholinergic crisis (muscle weakness) with overdose.

b) Ondansetron A 5-HT3 receptor antagonist. MOA: blocks serotonin (5-HT3) receptors both peripherally (vagal afferents, relevant to enterochromaffin-cell serotonin release) and centrally at the chemoreceptor trigger zone. Uses: chemotherapy-induced nausea and vomiting (first-line), postoperative nausea/vomiting, radiotherapy-induced emesis. Adverse effects: headache, constipation, QT prolongation (caution with other QT-prolonging drugs).

Other Years Asked


Revise MBBS
Preview