A patient on tramadol for pain management is started on sertraline for depression. Within 48 hours he develops agitation, diaphoresis, myoclonus, hyperreflexia, and hyperthermia. The pathophysiology of this reaction involves excess activity at which receptor?

• A D2 dopamine receptor
• B Alpha-2 adrenoreceptor
• C NMDA glutamate receptor
• D 5-HT1A and 5-HT2A serotonin receptors ✓

Explanation

Serotonin syndrome results from excess serotonergic activity, primarily through overstimulation of 5-HT1A and 5-HT2A receptors. It is distinguished from NMS by the triad of mental status changes, autonomic dysfunction, and neuromuscular abnormalities including myoclonus and hyperreflexia (rather than the 'lead pipe' rigidity of NMS). Tramadol inhibits serotonin reuptake and combined with sertraline (an SSRI) can precipitate serotonin syndrome. Treatment includes cyproheptadine (a 5-HT2A antagonist) and supportive care.

Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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