Phencyclidine toxicity

Note: this page is about the drug phencyclidine. For the infection, see PCP pneumonia

Background

• Phencyclidine (PCP) is a synthetic piperidine derivative, structurally similar to ketamine
• NMDA inhibitor, at high doses, can also act as norepinepherine/dopamine reuptake inhibitor, and interact with opioid, acetylcholine, and voltage-gated ion channel receptors
• Powdered ("angel dust") or liquid ("dippers") form
• Smoked, ingested orally, or intravenously injected
• Often combined with tobacco, marijuana ("wet"), crack cocaine, or other drugs.

Clinical Features

• Onset/duration of action dependant on route of administration; onset usually ~5 minutes if snorted, usually lasts 4-6 hours but can be longer if high dose
• Symptoms can fluctuate from CNS depression to excitation
• Wide range of symptoms due to PCP's cholinergic, anticholinergic, and sympathomimetic properties
  • Nystagmus (very common), ataxia
  • Hypertension, hypertensive crisis
  • Dissociation
  • Feelings of strength, invulnerability, hallucinations
  • Agitation, unpredictable behavior, violence
  • Tachycardia
  • Dystonia, muscle rigidity
  • Hyperthermia
• Excited delirium
  • Seizure
  • Coma or apparent comatose state (if very dissociated)

Evaluation

• Usually clinical diagnosis
• UDS: false positive screens for PCP can result from dextromethorphan, diphenydramine, doxylamine, ibuprofen, meperidine, tramadol, venlafaxine)
• Evaluate for dangerous effects of drug:
  • Occult trauma
  • Rhabdomyolysis
  • Hypoglycemia
  • Hepatic injury due to hyperthermia
  • End-organ damage due to hypertensive emergency
• Evaluate for other causes of presentation (e.g. other drugs, infection, endocrine/metabolic disorders, other causes of AMS)

Management

• Physical restraints only if danger to self and others
• Sedation: IV benzodiazepines
• Seizures: benzodiazepines, may require propofol and intubation for status epilepticus
• Active cooling if hyperthermic
• Hypertension: usually responds to benzos, but can use nitroprusside if severe/refractory
• IV fluids for rhabdomyolysis

Disposition

• Discharge if only minor medical complications and behavior normalizes

See Also

• Sympathomimetic toxicity
• Drugs of abuse
• Hallucinogens
• Excited delirium