Phencyclidine (PCP)-Related Psychiatric Disorders Clinical Presentation

Updated: Feb 14, 2018
  • Author: Jeffrey S Forrest, MD; Chief Editor: Ana Hategan, MD, FRCPC  more...
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Presentation

History

If a patient, or any family or friends who are present, can tell the physician reliably what substance has been used, it is obviously of help. Asking specifically about PCP can produce better information some of the time. However, because PCP is sold under other names, the historian may be honest as far as is known, but the history still may be inaccurate.

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Physical

The Mental Status Examination is the most important area of abnormality in PCP intoxication. A great deal of variability occurs in the mental status findings with these patients. At times, their exams may appear normal or nearly so, when a few minutes later (perhaps 20 or so), obvious psychosis and possible evidence of dangerousness to self and/or others appear. Therefore, one must document the hallucinations, delusions, and mood-related issues (such as suicidal and homicidal thinking) that are present carefully and with reference to the time of the examination, as well as commenting on any changes noted during the examination.

PCP-intoxicated individuals frequently seem to feel a need to undress, whether due to their elevated temperature or for some delusion-related impulse. These patients may appear highly distressed, often crying and upset and citing their suicidal and homicidal urges as related to this discomfort. Affective lability is also noted, with a wide range moving from normal or near-normal mood to rage, dysphoria and depression, or anxiety.

Orientation and other mental status measures of mentation are also important to document because PCP produces a drug-induced delirium as well as the psychosis. Concentration is poor, so serial 7 calculations or spelling the word "world" backwards or forwards is usually difficult for such patients. Judgment is impaired with impulsivity being commonly observed, as well as a seeming lack of normal fear. Insight widely varies from moment to moment and cannot be relied upon to remain stable over any period of time.

The physical examination may be difficult because these patients usually are not very cooperative but, if possible, look for increased deep tendon reflexes and nystagmus (particularly vertical but horizontal or rotatory nystagmus are also seen). Other evidence of loss of muscle coordination may also be noted. Typical anticholinergic findings are common because PCP is a highly anticholinergic substance. Elevations in vital signs are also often present for this reason, with tests of blood pressure and pulse, as well as temperature, likely to yield abnormally high findings. Keep in mind that PCP is related to the anesthetics, and the findings will be similar to those observed as people descend into dose-related anesthesia.

Physical examination findings of PCP-intoxicated individuals vary in accordance with the serum level of the drug, as follows:

  • Lower blood levels (20-30 ng/mL) cause a picture of sedation, irritability, hyperactivity, impaired attention, and mood elevation.

  • As the level rises above 30 ng/mL, physical examination show progressive levels of ataxia, paresthesias, and psychosis.

  • At 100 ng/mL, stimulant effects are noted most, with hypertension and hyperreflexia becoming more pronounced.

  • At levels of more than 100 ng/mL, stupor and seizures can occur. In this range, overdose-related death is possible.

A relatively unique and intriguing potential finding occasionally found in PCP intoxication is the presence of vertical nystagmus, which may help suggest the possibility of PCP intoxicatoin before a urine drug screen or history are available. An observational study of emergency room patients presumptively exposed to PCP demonstrated a significant number of patients with this finding. [4]

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Causes

Risk factors for use of PCP include the following:

  • Male sex (72%)

  • African American (54%) or Hispanic ethnicity

  • Young adult age range (62% of people treated for PCP overdose are in the second decade of life)

Obviously to ingest PCP, one must have access to this illicit substance, but it is fairly inexpensive and simple to synthesize and is thus relatively easy to obtain.

Sometimes, people who are intoxicated on PCP do not know that it is the drug they have received. Rather, the buyer of the drug is often told that he or she is getting something more exotic, such as "THC" or a designer drug.

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Complications

The abuse of PCP and its analogues such as 3-methoxy-phencyclidine have on occastion been implicated as causational of extreme (even homicidal) violence in patients with no prior violent history. [3]

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