A 24-year-old man is brought to the emergency department by police and emergency medical services personnel due to aggressive behavior toward his girlfriend. She reports that he has no history of medical or psychiatric illness and that this behavior is new. During transport, the patient was combative and difficult to restrain. He currently appears agitated, disoriented, and confused and seems to be responding to internal stimuli. Temperature is 37.2 C (99 F), blood pressure is 170/96 mm Hg, pulse is 118/min, and respirations are 20/min. Nystagmus and ataxia are present on initial neurologic examination. The patient does not cooperate with urine toxicology testing. His symptoms begin to resolve after 8 hours in the emergency department. He has very poor recollection of the previous night's events. Which of the following substances is most likely causing the constellation of symptoms seen in this patient?
Drug | Class | Clinical features |
PCP (phencyclidine) | Hallucinogen |
|
LSD | Hallucinogen |
|
Cocaine | Stimulant |
|
Methamphetamine | Stimulant |
|
Marijuana (THC, cannabis) | Cannabinoid |
|
Heroin | Opioid |
|
THC = tetrahydrocannabinol. | ||
This patient's combative behavior, confusion, poor judgment, memory loss, and hallucinations, accompanied by nystagmus and ataxia on physical examination, are consistent with phencyclidine (PCP) intoxication. PCP is a hallucinogen that works primarily as an N-methyl-D-aspartate glutamate receptor antagonist, as well as a monoamine reuptake inhibitor. PCP was originally developed as an anesthetic, but its use was discontinued due to its adverse effects in humans.
Moderate amounts of PCP cause dissociative symptoms, including detachment and withdrawal. At higher doses, it can induce agitation, hallucinations, and violent behavior. Ataxia and nystagmus (both horizontal and vertical) are other distinguishing symptoms of PCP abuse. Hospital urine toxicology screens usually test for PCP.
(Choice A) Signs and symptoms of cocaine intoxication include tachycardia, hypertension, blurry vision, euphoria, and agitation, typically lasting ≤1 hour. Ischemic effects (eg, myocardial infarction, stroke) can occur due to severe vasoconstriction.
(Choice B) The benzodiazepine diazepam is a central nervous system depressant that produces mild euphoria and relaxation and has significant abuse potential. Intoxication can cause mild amnesia, sedation, slurred speech, respiratory depression, hypotension, and bradycardia.
(Choice C) Heroin intoxication can produce euphoria, lethargy, and coma. Examination shows constricted pupils, decreased bowel sounds, low-normal blood pressure and heart rate, and life-threatening respiratory depression.
(Choice D) Lysergic acid diethylamide (LSD) is a potent hallucinogen with unpredictable effects, including euphoria, depersonalization, and visual illusions. Most patients are oriented and perceive that the effects are due to the drug ingestion. Nystagmus is not present.
(Choice E) Intoxication with the stimulant methamphetamine causes tachycardia, hypertension, agitation, diaphoresis, and hallucinations. Violent behavior may also be seen with its abuse, but nystagmus is less common. Methamphetamine intoxication typically lasts for up to 20 hours, longer than intoxication with PCP.
(Choice G) Marijuana is a cannabinoid that produces euphoria and perceptual distortions. Other findings include increased appetite, red eyes, slowed reflexes, dizziness, and impaired coordination. Nystagmus is not common.
Educational objective:
Phencyclidine (PCP) is a hallucinogen that causes dissociative symptoms, agitation, hallucinations, and violent behavior. Ataxia, nystagmus, and memory loss are other distinguishing symptoms of PCP abuse.