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Phencyclidine (PCP)-Related Psychiatric Disorders Medication

  • Author: Alan D Schmetzer, MD; Chief Editor: Iqbal Ahmed, MBBS, FRCPsych(UK)  more...
Updated: Dec 29, 2015

Medication Summary

Benzodiazepines are the medication of choice when treating acute PCP intoxication.



Class Summary

Treat symptoms of aggressivity and may decrease the likelihood of seizures and psychotic complications in PCP intoxication.

Lorazepam (Ativan)


DOC; may be used IV and is well-absorbed after IM injection. Onset of action occurs within minutes of an injection and effects peak 15-20 minutes after injection. Duration of action is 6-8 h. No active metabolites exist.

Diazepam (Valium, Diastat)


Historically, this medication has been the most helpful benzodiazepine in treating acute PCP intoxication. Even the psychotic symptoms respond sometimes. Diazepam is not absorbed reliably IM, but it can be administered both PO and IV. If IV administration is contemplated, decrease dose and be prepared to treat possible respiratory depression. If IM route is used, consider lorazepam as alternative, with dosage range of 1-2 mg.


Antipsychotic agents

Class Summary

These agents are useful when PCP-induced psychotic symptoms do not respond adequately to benzodiazepines or when benzodiazepines are contraindicated. Avoid using highly anticholinergic antipsychotics because PCP is fairly anticholinergic.

Risperidone (Risperdal)


Atypical antipsychotic medication. Has lower incidence of extrapyramidal adverse effects than traditional neuroleptics, such as haloperidol. Binds to dopamine D2 receptor with 20 times lower affinity than for 5-HT2 receptor. Improves negative symptoms of psychoses and reduces incidence of extrapyramidal adverse effects. Similarly, other newer atypical antipsychotics, such as olanzapine or quetiapine, may also be effective. Risperidone has a quick-dissolving oral formulation, Risperdal M-Tab.

Ziprasidone (Geodon)


Available in tab and a parenteral form.

Contributor Information and Disclosures

Alan D Schmetzer, MD Professor Emeritus, Department of Psychiatry, Indiana University School of Medicine

Alan D Schmetzer, MD is a member of the following medical societies: American Academy of Addiction Psychiatry, American Academy of Clinical Psychiatrists, American Academy of Psychiatry and the Law, American Association for Physician Leadership, American Medical Association, American Psychiatric Association, International Society for ECT and Neurostimulation, American Neuropsychiatric Association

Disclosure: Nothing to disclose.


David R Diaz, MD, DFAPA Associate Professor of Clinical Psychiatry, Indiana University School of Medicine; Medical Director, Unit 3C, Larue D Carter Memorial Hospital

David R Diaz, MD, DFAPA is a member of the following medical societies: Academy of Psychosomatic Medicine, American Psychiatric Association, Indiana State Medical Association, National Hispanic Medical Association, Indiana Psychiatric Society, Indianapolis Medical Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Iqbal Ahmed, MBBS, FRCPsych(UK) Faculty, Department of Psychiatry, Tripler Army Medical Center; Clinical Professor of Psychiatry, Uniformed Services University of the Health Sciences; Clinical Professor of Psychiatry, Clinical Professor of Geriatric Medicine, University of Hawaii, John A Burns School of Medicine

Iqbal Ahmed, MBBS, FRCPsych(UK) is a member of the following medical societies: Academy of Psychosomatic Medicine, American Neuropsychiatric Association, American Society of Clinical Psychopharmacology, Royal College of Psychiatrists, American Association for Geriatric Psychiatry, American Psychiatric Association

Disclosure: Nothing to disclose.

Additional Contributors

Barry I Liskow, MD Professor of Psychiatry, Vice Chairman, Psychiatry Department, Director, Psychiatric Outpatient Clinic, The University of Kansas Medical Center

Disclosure: Nothing to disclose.

Roland McGrath, MD 

Roland McGrath, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.


The authors would like to acknowledge Indiana University School of Medicine, William Niles Wishard Memorial Hospital, and Larue D. Carter Memorial Hospital for their support of the faculty involved in the preparation of this Medscape Reference article.

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PCP molecule.
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