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DESCRIPTION
Phencyclidine is a drug of abuse that produces hallucinations.
FORMS AND USES
- Phencyclidine is commonly known as PCP.
- Slang terms include angel dust, hog, mist, peace pill, kayo jay, KJ, crystal joint, elephant tranquilizer, super grass, super weed, rocket fuel, scuffle, sheets, space basing (phencyclidine plus crack cocaine), DOA, T, cyclone, snorts, soma, goon, horse franks, and dust.
- PCP is often used to enhance the effects of other drugs (e.g., "dipping" a marijuana joint).
TOXIC DOSE
- A dose of 5 mg will usually produce euphoria.
- A dose of 150 to 200 mg has been associated with death.
PATHOPHYSIOLOGY
- Phencyclidine is a dissociative anesthetic.
- It stimulates alpha-adrenergic receptors, causing sympathomimetic effects.
- It also has hallucinogenic effects and is believed to potentiate the effects of serotonin.
EPIDEMIOLOGY
- Poisoning from recreational abuse is common.
- Incidence of abuse is highly regional.
- Toxic effects are typically mild to moderate.
- Death is rare and usually caused by trauma incurred due to impaired judgment.
CAUSES
- Cause is usually intentional ingestion or inhalation.
- The possibility of child neglect or abuse should be considered if the patient is less than 1 year of age; suicide attempt in patients over 6 years of age.
RISK FACTORS
Elderly patients may be less tolerant of the cardiovascular effects.
DRUG AND DISEASE INTERACTIONS
Sympathomimetic effects may be enhanced by other sympathomimetic drugs such as cocaine or amphetamines.
PREGNANCY AND LACTATION
- US FDA Pregnancy Category X. Studies demonstrate fetal abnormalities or there is evidence of fetal risk based on human experience, or both, and the risk outweighs any possible benefit.
- Phencyclidine crosses the placenta and may produce toxicity in the fetus.
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DIFFERENTIAL DIAGNOSIS
- Toxic causes of hallucinations include amphetamines, anticholinergic agents, high-dose corticosteroids, LSD, peyote, psilocybin, and mescaline, among others.
- Nontoxic causes include CNS trauma, meningitis, AIDS-related illness, hypoglycemia, electrolyte imbalance, heat-related illness, hypoxia, and alcohol or sedative-hypnotic withdrawal.
SIGNS AND SYMPTOMS
- Common effects include nystagmus, hypertension, tachycardia, agitation, hallucinations, and violent behavior.
- Associated conditions are complications of drug abuse (hepatitis, abscess, HIV, endocarditis, etc.).
Vital Signs
- Hyperthermia or hypothermia may develop depending on degree of physical activity and ambient temperature.
- Tachycardia and hypertension are common.
HEENT
- Nystagmus is common and may be horizontal, vertical, or rotatory.
- Mydriasis occurs with severe intoxication.
- Miosis is more common in children.
Cardiovascular
Hypertension and mild tachycardia are common.
Pulmonary
Apnea and respiratory failure may occur after severe overdose.
Renal
Acute renal failure may develop rarely due to rhabdomyolysis.
Musculoskeletal
Rhabdomyolysis may occur due to prolonged agitation or hyperthermia.
Neurologic
- Common findings include impaired judgment, agitation, violent behavior, delusions or hallucinations, psychosis, and paranoid or self-destructive behavior.
- Coma occurs infrequently.
- Seizures, dystonia, and dyskinesia occur rarely.
Endocrine
Mild hypoglycemia is common.
PROCEDURES AND LABORATORY TESTS
Essential Tests
No tests may be needed in asymptomatic patients with a history of possible ingestion.
Recommended Tests
- Serum electrolytes, glucose, BUN, and creatine levels should be determined in symptomatic patients.
- Mild hypoglycemia is common.
- Rhabdomyolysis and renal failure imply prolonged agitation and severe intoxication.
- ECG and cardiac monitoring may reveal tachycardia; other dysrhythmias suggest severe intoxication.
- Serum creatine kinase may be determined to detect rhabdomyolysis.
- Liver function and coagulation studies are performed in symptomatic patients to assess the severity of toxicity.
- Urine drug screening may be performed in patients with hallucinations of unknown cause to determine toxic effects and the presence of other ingestants.
- Urinalysis may be performed to determine renal injury produced by rhabdomyolysis or hypotension.
- Other tests (complete blood count, blood culture, head CT, lumbar puncture) should be performed as needed to rule out other causes of mental status change.
Not Recommended Tests
Serum phencyclidine levels are not available or helpful.
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- Treatment focuses on supporting blood pressure, managing airway, and controlling agitation.
- Dose and time of exposure should be determined for all substances involved.
DIRECTING PATIENT COURSE
The health-care provider should call the poison control center when:
- Seizure, coma, dysrhythmia, severe hypertension or hyperthermia, or other serious effects are present.
- Toxic effects are not consistent with phencyclidine poisoning.
- Coingestant, drug interaction, or underlying disease presents an unusual problem.
The patient should be referred to a health-care facility when:
- Attempted suicide or homicide is possible.
- Patient or caregiver seems unreliable.
- Toxic effects develop.
- Coingestant, drug interaction, or underlying disease presents an unusual problem.
Admission Considerations
Inpatient treatment is warranted when there is persistent alteration in mental status or when end-organ complications, such as rhabdomyolysis or renal failure, develop.
DECONTAMINATION
- Gastrointestinal decontamination is not usually recommended because of the small amount of phencyclidine needed to produce hallucinations and its rapid absorption.
- Lavage or activated charcoal may be appropriate if other drugs were ingested.
ANTIDOTES
There is no specific antidote for phencyclidine poisoning.
ADJUNCTIVE TREATMENT
Agitation or Psychosis
For control of agitation or psychosis, a number of strategies may be used:
- Naloxone and D50W should be administered if appropriate.
- The patient should be placed in a dimly lit room and offered counseling and companionship, to be "talked down."
- A benzodiazepine familiar to the provider should be administered.
- The airway should be monitored closely.
Diazepam
- Adult dose is 5 to 10 mg intravenously.
- Pediatric dose is 0.2 to 0.5 mg/kg intravenously.
- Doses are repeated at 5- to 10-minute intervals, titrating to effect.
Lorazepam
- Adult dose is 1 to 2 mg intravenously.
- Pediatric dose is 0.05 mg/kg intravenously.
- Doses are repeated at 5- to 10-minute intervals, titrating to effect.
Neuroleptics
- Neuroleptics such as droperidol should be used only in refractory cases
- Neuroleptics may induce seizure by lowering seizure threshold.
Mild Hypertension
Primary treatment is control of agitation.
Severe Hypertension
- For persistent severe hypertension or if end-organ damage is present, intravenous infusion of nitroprusside 1 µg/kg/min should be started and titrated up to 10 µg/kg/min as needed to control blood pressure.
- If infusion is required for more than 24 hours, the patient should be monitored for cyanide intoxication.
Hyperthermia
- Clothing should be removed and intravenous infusion of isotonic crystalloid begun.
- Agitation should be controlled.
- Fluid losses may be severe and should be replenished until a urine output of 1 to 2 ml/kg/h is reached.
- Fluid infusion should be monitored carefully to avoid overload.
- Cooling fans and wet sheets are effective, especially in dry climates.
- Other forms of central cooling (ice application, iced lavage fluids) are also recommended.
- Core temperature should be monitored frequently and cooling discontinued when body temperature decreases to 39°C.
Seizures
- Patent airway should be assured.
- A benzodiazepine should be administered for initial control as described for agitation, above.
- If seizures persist or recur, another anticonvulsant such as phenobarbital or phenytoin should be added.
Rhabdomyolysis
- Adequate hydration and urine output (1-2 ml/kg/h) should be ensured.
- Urinary alkalinization has not proven beneficial.
Not Recommended Therapies
Urinary acidification increases urinary excretion of phencyclidine by ion trapping, but carries a serious risk of inducing acidemia and worsening acute tubular necrosis in patients with rhabdomyolysis.
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EXPECTED COURSE AND PROGNOSIS
- Effects usually peak within several hours and then abate over 24 hours or more.
- Patients with repeated seizures are more likely to die or sustain permanent neurologic injury.
- Possible complications include renal failure, CNS injury due to prolonged seizures, and complications of trauma due to impaired judgment.
DISCHARGE CRITERIA/INSTRUCTIONS
- The patient may be discharged from the emergency department or hospital when tachycardia, hypertension, and hyperthermia have resolved and mental status has returned to baseline, provided there is no evidence of trauma or end-organ injury.
- The patient should be referred for substance abuse treatment.
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DIAGNOSISBefore attributing hallucinations to phencyclidine, other causes must be excluded.
TREATMENT
- Large amounts of benzodiazepines may be needed to control agitation.
- Severe hyperthermia may be life threatening and requires aggressive cooling and control of agitation.
- Patients may be extremely violent and a danger to themselves and others.
ICD-9-CM 968Poisoning by other central nervous system depressants and anesthetics.
See Also: SECTION II, Hyperthermia and Seizures chapters; and SECTION III, Nitroprusside chapter.
RECOMMENDED READING
McCarron MM, Schulze BW, Thompson GA, et al. Acute phencyclidine intoxication: clinical pattern, complications and treatment. Ann Emerg Med 1981;10:290-297.
Author: Katherine M. Hurlbut
Reviewer: Richard C. Dart