Protamine action — FRCA Primary MCQ

Correct answer: D — It chelates unfractionated heparin

Protamine forms a stable complex with heparin and neutralises its anticoagulant effect. It inhibits prostaglandin synthesis is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It inhibits plasminogen activation is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It undergoes Hofmann elimination is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It antagonises NMDA receptors is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA pharmacology, link the clinical effect to the receptor, distribution or elimination mechanism rather than memorising isolated facts.

Reference: Peck, Hill & Williams Pharmacology for Anaesthesia and Intensive Care; BNF; Primary FRCA textbooks