A 50-year-old patient receiving intravenous vancomycin develops pruritus, erythema on the face and neck, and mild hypotension during the infusion. What is the most likely mechanism?
- A IgE-mediated anaphylaxis
- B Direct histamine release from mast cells ✓
- C Complement activation
- D Cytokine release syndrome
Correct answer: B. Direct histamine release from mast cells
Explanation
Red man syndrome is caused by non-immune-mediated direct histamine release from mast cells due to rapid vancomycin infusion, not IgE-mediated anaphylaxis. Slowing the infusion and pre-treatment with antihistamines prevent it. It is a dose- and infusion-rate-dependent reaction.
Reference: Katzung: Basic & Clinical Pharmacology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.