From the Guidelines
PCP intoxication can be differentiated from other substance intoxications by its unique constellation of symptoms, including nystagmus, hypertension, tachycardia, hyperthermia, diaphoresis, ataxia, and distinctive behavioral changes. To distinguish PCP intoxication from other substance intoxications, it is essential to consider the patient's clinical presentation. PCP typically causes a combination of stimulant and dissociative effects simultaneously, with patients often demonstrating bizarre strength and pain insensitivity. Unlike other hallucinogens, PCP frequently causes vertical or horizontal nystagmus and can induce a schizophrenia-like psychosis with thought disorders. Some key points to consider when differentiating PCP intoxication from other substance intoxications include:
- The presence of nystagmus, which is a characteristic feature of PCP intoxication 1
- The combination of stimulant and dissociative effects, which is unique to PCP 1
- The patient's behavioral changes, including agitation, violent behavior, and a blank stare 1
- The potential for PCP to induce a schizophrenia-like psychosis with thought disorders 1 Laboratory confirmation through urine drug screening is helpful, but results may take time. Management focuses on supportive care in a quiet environment, with benzodiazepines like lorazepam 1-2mg IV for agitation. Avoid physical restraints when possible as they may worsen agitation and potentially lead to rhabdomyolysis. PCP's unique pharmacology as an NMDA receptor antagonist explains its dissociative effects and distinctive clinical presentation that separates it from pure stimulants, opioids, or other hallucinogens. Monitor for complications including hyperthermia, rhabdomyolysis, and seizures, as these may require specific interventions.
From the Research
Differentiating PCP Intoxication from Other Substance Intoxications
To distinguish PCP (phencyclidine) intoxication from other substance intoxications, several key factors and symptoms must be considered:
- Clinical Presentation: PCP intoxication can present with a wide range of symptoms, including schizophrenia-like delusions and hallucinations, mania, violence, dyskinetic, catatonic, or stereotyped movements, hypertension, and coma 2, 3.
- Dose-Related Effects: The effects of PCP can vary based on the dose consumed. Low to moderate doses (5-20 mg) may result in an acute, confusional state, while high doses (greater than 20 mg) can lead to serious neurologic and cardiovascular complications, often resulting in coma 4.
- Psychological and Medical Measures: Treatment involves supportive psychological and medical measures. Specific medications like diazepam, haloperidol, and chlorpromazine may be used to control agitation, psychotic symptoms, and combative behavior 2, 4, 5.
- Medical Complications: Patients intoxicated with PCP are at risk for significant medical complications, including rhabdomyolysis, seizures, hyperthermia, and in severe cases, death 3, 6.
- Diagnostic Approach: The diagnosis of PCP intoxication should consider the patient's history, physical examination, and laboratory tests, including toxicology screens. The clinical patterns of PCP intoxication, such as acute brain syndrome, toxic psychosis, catatonic syndrome, and coma, can guide the diagnostic and treatment approach 6.
Key Symptoms and Treatment Considerations
Some key symptoms and treatment considerations that can help differentiate PCP intoxication include:
- Violence and Agitation: PCP-intoxicated patients are often violent and difficult to control, necessitating the use of chemical restraints like haloperidol 5.
- Antidotes and Treatments: While there is no specific antidote for PCP toxicity, treatments such as acidification of the urine, diazepam for agitation, and haloperidol for psychotic symptoms can be effective 2, 4.
- Supportive Care: Supportive care, including monitoring of vital signs, management of medical complications, and protection of the patient from self-harm, is crucial in the management of PCP intoxication 3, 6.