A young man develops agitation, hyperreflexia, clonus and diarrhoea after starting a tramadol-duloxetine combination. Alongside supportive care, the antidote that acts by blocking postsynaptic serotonin receptors is:
- A Naloxone
- B Flumazenil
- C Cyproheptadine ✓
- D Physostigmine
Correct answer: C. Cyproheptadine
Explanation
Cyproheptadine is an antagonist at 5-HT2A receptors, the subtype principally implicated in serotonergic toxicity, and is the accepted pharmacological antidote for serotonin syndrome when supportive measures fail. Tramadol plus duloxetine produced additive serotonergic excess. Naloxone reverses opioid effects, flumazenil benzodiazepines, and physostigmine treats anticholinergic syndromes; none addresses the 5-HT2A mediated hyperthermia, clonus and neuromuscular findings that define this condition.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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