A 20-year-old man is brought comatose from a party. He is hypertensive, tachycardic, and hyperreflexic with analgesia to painful stimuli. The examining resident notes prominent horizontal and vertical nystagmus. Which substance best explains this combination?
- A Phencyclidine ✓
- B Cocaine
- C Amphetamine
- D Lysergic acid diethylamide
Correct answer: A. Phencyclidine
Explanation
Phencyclidine (PCP) uniquely combines a sympathomimetic presentation with nystagmus, classically horizontal, vertical, or rotatory, along with analgesia, hypertension, and fluctuating consciousness. Nystagmus with coma is the discriminating sign because pure sympathomimetics like amphetamine and cocaine cause mydriasis and hypertension without nystagmus or marked analgesia. LSD causes perceptual distortion and mild sympathetic signs but does not produce coma or nystagmus.
Reference: Goldfrank's Toxicologic Emergencies, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.