Phencyclidine toxicity

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.

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)

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)

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

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