A patient presents with agitation, hyperthermia, clonus and hyperreflexia after combining an SSRI with tramadol. Which antihistaminic agent, acting through additional receptor properties, is used as a specific antidote in serotonin syndrome?
- A Hydroxyzine
- B Cyproheptadine ✓
- C Chlorpheniramine
- D Fexofenadine
Correct answer: B. Cyproheptadine
Explanation
Cyproheptadine is a first-generation antihistamine with potent 5-HT2A receptor antagonist activity, and blockade of 5-HT2A receptors underlies its role as the specific antidote in serotonin syndrome. Hydroxyzine and chlorpheniramine lack meaningful serotonergic antagonism, and fexofenadine, a second-generation agent, does not reach sufficient brain levels nor block 5-HT2 receptors. Supportive care and benzodiazepines accompany cyproheptadine therapy.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th ed.
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