Sequestration in acidic gastric contents — rationale for historical acidification (now abandoned)
Therapeutic Considerations
Benzodiazepine-first strategy
Diazepam historically preferred as it addresses multiple PCP effects simultaneously
Agitation and behavioral dyscontrol
Seizure prevention and treatment
Muscle relaxation reducing rhabdomyolysis risk
Indirect antihypertensive effect via sedation
Phenothiazines avoided — lower seizure threshold and anticholinergic side effects
Chlorpromazine specifically contraindicated by some toxicologists
Antipsychotic use considerations
Haloperidol has demonstrated benefit for schizophreniform PCP symptoms
1982 controlled trial (Castellani) showed improvement vs physostigmine
Reasonable adjunct when benzodiazepines alone insufficient for psychosis
Butyrophenones (haloperidol, droperidol) preferred over phenothiazines
Monitor QTc with any antipsychotic use
Urinary acidification — historically advocated, now contraindicated
Ion trapping in acidic urine increases PCP ionization and excretion
Ammonium chloride and ascorbic acid were used
Abandoned due to risk of worsening rhabdomyolysis renal injury
Metabolic acidosis worsening is additional contraindication
Stimulation reduction as therapy
Quiet dark environment is a documented therapeutic intervention
Reduces sensory-driven agitation and hyperthermia generation
Physical restraints avoided when possible — exacerbate hyperthermia
Patient Discharge Instructions
copy discharge instructions
What happened in the emergency department
Treated for phencyclidine (PCP) intoxication
Blood and urine tests performed to check kidney function and muscle breakdown
IV fluids given to protect kidneys if muscle breakdown was detected
Home care instructions
Rest and avoid strenuous activity for 48-72 hours
Drink plenty of fluids — water or electrolyte drinks
Do not drink alcohol or use any recreational substances
Do not drive or operate machinery until fully recovered
Avoid environments where PCP or other drugs are used
Warning signs — return to emergency department immediately
Confusion or unusual behavior returning
Dark, brown, or tea-colored urine (could indicate kidney damage)
Inability to urinate
Muscle pain, weakness, or swelling
Seizure or convulsion
Fever higher than 38.5 C
Severe headache or neck stiffness
Chest pain or palpitations
Worsening agitation or seeing or hearing things that are not there
Important information about PCP
PCP effects can last several days — mood and thinking may remain affected
PCP can trigger prolonged mental health symptoms lasting weeks
PCP is often present in other drugs without your knowledge (marijuana, other pills)
Follow-up appointments
Repeat blood tests in 48-72 hours if kidney or muscle issues were found
Mental health follow-up appointment arranged before discharge
Substance use counseling and addiction services referral
Family physician follow-up within 1-3 days
References
Guidelines and key sources
Landmark clinical studies
McCarron MM et al. Acute Phencyclidine Intoxication: Incidence of Clinical Findings in 1,000 Cases. Annals of Emergency Medicine 1981; PMID 7224271
McCarron MM et al. Acute Phencyclidine Intoxication: Clinical Patterns, Complications, and Treatment. Annals of Emergency Medicine 1981; PMID 7235337
Castellani S, Giannini AJ, Adams PM. Physostigmine and Haloperidol Treatment of Acute Phencyclidine Intoxication. Am J Psychiatry 1982; PMID 7065301
Akmal M et al. Rhabdomyolysis With and Without Acute Renal Failure in Patients With Phencyclidine Intoxication. Am J Nephrology 1981; PMID 7349047
Key references
Tong TG et al. Phencyclidine Poisoning. JAMA 1975; PMID 1242170
Barton CH et al. Phencyclidine Intoxication: Clinical Experience in 27 Cases Confirmed by Urine Assay. Ann Emerg Med 1981; PMID 7224272
Showalter CV, Thornton WE. Clinical Pharmacology of Phencyclidine Toxicity. Am J Psychiatry 1977; PMID 910974
Cogen FC et al. Phencyclidine-Associated Acute Rhabdomyolysis. Ann Intern Med 1978; PMID 626451
Society guidelines and updates
Lavonas EJ et al. 2023 AHA Focused Update on Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning. Circulation 2023
Isoardi KZ et al. Best Approach for Parenteral Sedation to Manage Severe Acute Behavioral Disturbance in the ED. Clinical Toxicology 2026; PMID 41355751
Kim HK et al. Safety and Efficacy of Pharmacologic Agents for Rapid Tranquilization of ED Patients With Acute Agitation. Expert Opinion Drug Safety 2021; PMID 33327811
Coding reference
ICD-10 T41.291A — Poisoning by other general anesthetics, initial encounter
ICD-10 F16.10 — Hallucinogen abuse, uncomplicated (PCP classified under hallucinogens)
SNOMED CT — Phencyclidine poisoning (disorder)
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.