A 24-year-old man is brought to the emergency department after a party where he took an unknown drug. He is combative, has severe vertical and horizontal nystagmus, marked analgesia, hypertension, and does not respond normally to painful stimuli. Which substance best explains this presentation?
- A LSD
- B Phencyclidine (PCP) ✓
- C Cocaine
- D MDMA
Correct answer: B. Phencyclidine (PCP)
Explanation
Phencyclidine, an NMDA receptor antagonist, characteristically produces dissociative anaesthesia, profound analgesia, violence or agitation, hypertension, and nystagmus, which may be horizontal, vertical, or rotatory. The combination of nystagmus with marked analgesia is highly suggestive of PCP because LSD, cocaine, and MDMA cause mydriasis and sympathetic overactivity but do not produce nystagmus or significant analgesia.
Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.