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Phencyclidine (PCP)-Related Psychiatric Disorders: Treatment & Medication
Updated: May 31, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Medical Care
For good medical care of these patients, one must consider both the variability of their presentations and the high risk of violence to self and/or others during the time of drug-induced psychosis. For these reasons, these patients must often be admitted to a psychiatric inpatient unit for safety reasons. In the intensive care area, where these patients may be admitted for overdoses, treatment is aimed primarily at decreased absorption by induced emesis and/or gastric lavage and charcoal. In medical or psychiatric settings, the judicious use of leather restraints may be necessary to protect these patients from harming themselves, other patients, and staff members. Use of a benzodiazepine and/or an antipsychotic medicine, particularly those that are not highly anticholinergic, will often help to reduce risk, but remember that risk is not entirely eliminated.
- Once the diagnosis has been established, the treatment of choice is generally considered to be benzodiazepine tranquilization. Typically, diazepam is used first, unless liver damage is present. In case of liver damage, other benzodiazepines that do not undergo oxidative metabolism by the liver, such as lorazepam, can be administered. Starting at 10 mg, titrate diazepam until the patient is sufficiently sedated. Monitor respiratory status. Use of diazepam often treats PCP-induced aggressiveness, psychotic symptoms, hypertension, and tachycardia.
- If psychosis remains problematic, consider the addition of an antipsychotic. In the past, this would often have been haloperidol, but now that short-acting injectable ziprasidone and olanzapine for intramuscular administration, and quick-dissolving olanzapine and risperidone for oral use are available, these are generally considered to be better alternatives. When antipsychotics are necessary, always use one that is low in anticholinergic activity because of the anticholinergic properties of PCP itself.
- In the past, acidification of the urine was performed using ammonium chloride, but this generally is not recommended currently because of the possibility of renal toxicity, metabolic acidosis, and increased risk of rhabdomyolysis.
- Keep the possibility of seizures, coma, and death in mind with higher (>100 ng/mL) levels of PCP and be prepared to support respiration if needed.
- Following acute medical stabilization, psychiatric care is indicated. The patient may require transfer to a psychiatric unit if psychosis is not under adequate control.
- Evaluate for chemical dependence once the patient is no longer psychotic, and refer him or her for treatment if appropriate. This is a serious and potentially fatal drug of abuse. PCP intoxication and abuse should be regarded with the same seriousness as any other potentially life-threatening conditions.
- Tennant and colleagues have suggested the use of tricyclic antidepressants, such as desipramine, for withdrawal when dependence is present.11
Surgical Care
Remember that the PCP-intoxicated patient is, to some greater or lesser extent, anesthetized and may have sustained injury to bones or internal organs without showing the usual pain response. Surgical assessment for such injuries, if suspected, may be life-saving.
Consultations
Obtain psychiatric consultation if the patient is in the emergency department or a general medical unit. If a separate consultation team for addictive disorders is available, ask that group to evaluate the patient. Likewise, if the patient is in a psychiatric unit or in the psychiatry emergency department, consultation with internal medicine and/or addiction subspecialists may be indicated. For people using PCP who may appear to have been injured, orthopedic or surgical consults may be necessary because the anesthetic nature of the substance can mask the usual discomfort of fractures and/or internal injuries rendering the usual assessments of seriousness of the condition difficult or impossible.
Diet
Acidification of the urine by adding ammonium chloride, for example, is controversial, and at present is generally not recommended. While a more acidic urine may allow for faster excretion of PCP and its matabolites, such higher concentrations may also be harmful to the kidneys, produce a metabolic acidosis, or increase the likelihood of rhabdomyolysis.
Although in general this is presently not recommended, if for some reason an acidifying agent seems indicated, the common approach is use of ammonium chloride administered by slow intravenous infusion. (In the past, ammonium chloride was sometimes administered orally as an acidifying agent; however, an oral dosage form of the drug is no longer commercially available in the United States.) Solutions of the drug should not be administered subcutaneously, intraperitoneally, or rectally. The injection concentrate of 26.75% must be diluted in 0.9% sodium chloride injection prior to administration. A dilute solution may be prepared by adding 100 or 200 mEq of ammonium chloride (20 or 40 mL of the 26.75% injection) to 500 or 1000 mL of 0.9% sodium chloride injection. For IV infusion, the dilute solution should be administered at a rate not exceeding 5 mL/min in adults.
Activity
Patients may require seclusion and/or restraint while acutely intoxicated with PCP. Those who are intoxicated with PCP can be highly violent and confused, and they often complain of very disturbing thoughts about harming themselves or others. Current regulations require frequent monitoring of all persons in seclusion or restraint, including a face-to-face assessment by an independent, licensed practitioner within 1 hour of initiation. Suicide and assault precautions are often necessary. When ataxia is present, do not allow ambulation without assistance because of the risk of injury in falls.
Medication
Benzodiazepines are the medication of choice when treating acute PCP intoxication.
Benzodiazepines
Treat symptoms of aggressivity and may decrease the likelihood of seizures and psychotic complications in PCP intoxication. Intramuscular benzodiazepine preparation is desirable when there is severe agitation or the need to avoid a gastrointestinal route for administration.
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.
Adult
4 mg IV/IM; may repeat q15min prn; not to exceed 8 mg
Pediatric
0.1 mg/kg IV; maximum rate 2 mg/min; not to exceed 4 mg/dose
Toxicity of benzodiazepines in CNS increases when used concurrently with alcohol, phenothiazines, barbiturates, and MAOIs
Documented hypersensitivity; preexisting CNS depression, hypotension, and narrow angle glaucoma; reversal agents (eg, flumazenil) contraindicated when lorazepam used for life-threatening conditions (eg, control of intracranial pressure or status epilepticus)
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in renal or hepatic impairment, myasthenia gravis, organic brain syndrome, or Parkinson disease
Diazepam (Valium)
This drug usually is 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.
Adult
5-10 mg PO or 2-5 mg IV
Pediatric
0.05-0.3 mg/kg/dose over 2-3 min IV/IM; repeat in 2-4 h prn
0.12-0.8 mg/kg/d PO divided q6-8h; not to exceed 10 mg/dose
Toxicity of benzodiazepines in CNS increased when coadministered with CNS depressants such as phenothiazines, barbiturates, alcohols, and MAOIs
Documented hypersensitivity
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Benzodiazepines generally are considered to be teratogenic (research on this is being reviewed, and recommendations may change over time); if patient is pregnant, especially in first trimester, use low-dose high-potency antipsychotics first to test for sufficient effect; caution with other CNS depressants, low albumin levels, or hepatic disease (may increase toxicity)
Antipsychotic agents
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. Agents with various routes of administration also useful in PCP psychosis.
Olanzapine (Zyprexa, Zyprexa Zydis)
May inhibit serotonin, muscarinic and dopamine effects. Available as tablets, oral disintegrating tablets (Zyprexa Zydis), and an intramuscular dosage form.
Adult
5-10 mg PO qd and increase to 10 mg qd within 5-7 d; adjust by 5 mg/d at 1 wk interval to a maximum of 20 mg/d
Agitation associated with schizophrenia: 10 mg IM once; may repeat after 2 h; not to exceed 30 mg/24 h
Geriatric or debilitated individuals: 2.5-5 mg IM/dose
Pediatric
Not established
Fluvoxamine may increase effects of olanzapine; antihypertensives may increase risk of hypotension and orthostatic hypotension; levodopa, pergolide, bromocriptine, charcoal, carbamazepine, omeprazole, rifampin, and cigarette smoking may decrease the effects of olanzapine
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in narrow-angle glaucoma, cardiovascular disease, cerebrovascular disease, prostatic hypertrophy, seizure disorders, hypovolemia, and dehydration; hyperglycemia may occur and in some cases be extreme, resulting in ketoacidosis, hyperosmolar coma, or death; administration of more than one IM injection is associated with substantial orthostatic hypotension (33%), maintain patient in recumbent position and monitor blood pressure before repeating IM doses
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 and olanzapine now have quick-dissolving oral formulations.
Adult
1 mg PO bid initially and slowly increase as necessary to optimum range of 4-8 mg/d; doses >10 mg/d do not appear to offer additional benefit
Pediatric
Not established
Coadministration with carbamazepine may decrease effects; risperidone may inhibit effects of levodopa; clozapine may increase risperidone levels; interacts with other CNS depressants
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
While less likely than with the traditional antipsychotics, both extrapyramidal adverse effects and neuroleptic malignant syndrome are possible; renal or liver disease may require reduced dosage, since these conditions could affect metabolism and excretion
Ziprasidone (Geodon)
Now available in an injectable form. Becoming more commonly used for acute psychosis.
Adult
10-20 mg PO/IM up to q2h; not to exceed 40 mg/d
Pediatric
Pediatric dose: Not established
Adolescents: Administer as in adults
Ziprasidone is not known to significantly increase or decrease serum levels of other medications, but it should not be given concurrently with another medication that also prolongs QT interval; carbamazepine lowers serum level of ziprasidone, whereas ketoconazole increases it, which is also likely to be true with other agents that induce or inhibit CYP3A4, respectively
Documented hypersensitivity; prolonged QT interval
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Monitor for tachycardia, postural hypotension, and somnolence, effects that are probably dose related; risk of neuroleptic malignant syndrome (discontinue antipsychotic if this is suspected), while lower than with agents such as haloperidol, is nonetheless still present
More on Phencyclidine (PCP)-Related Psychiatric Disorders |
| Overview: Phencyclidine (PCP)-Related Psychiatric Disorders |
| Differential Diagnoses & Workup: Phencyclidine (PCP)-Related Psychiatric Disorders |
 Treatment & Medication: Phencyclidine (PCP)-Related Psychiatric Disorders |
| Follow-up: Phencyclidine (PCP)-Related Psychiatric Disorders |
| Multimedia: Phencyclidine (PCP)-Related Psychiatric Disorders |
| References |
| Further Reading |
| « Previous Page | Next Page » |
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Further Reading
Gorelick DA, Balster RL. Phencyclidine (PCP). Back to Psychopharmacology - The Fourth Generation of Progress
Pinchot JT, Schmetzer AD. Phencyclidine bibliography, for AAAP - Resource Site for the PGY-5 Curriculum Project, July 2001
Books and book chapters on PCP:
Hafen B, Frandsen K. Phencyclidine - Angel Dust: By any name not fit for human consumption. Hazelden Foundation, 1980.
Carroll M. The dangerous angel. In: Snyder SH, ed. The Encyclopedia of Psychoactive Drugs. Chelsea House Publishers, 1985, ISBN: 087754753X
Ogelsby EW, Faber S, Faber S. Angel Dust - What everyone should know about PCP. Charing Cross Publishing Company, 1982, ISBN: 0890740666
Keywords
phencyclidine-related psychiatric disorders, PCP, angel dust, crystal, hog, krystal joint, KJ, mintweed, rocket fuel, delta-9-tetrahydrocannabinol, THC, N -methyl-D-aspartate, NMDA, lysergic acid diethylamide, LSD, substance-induced psychosis, 1-(phenylcyclidine) piperidine
