PCP Overdose Signs and Treatment

PCP (phencyclidine) is classified as a dissociative hallucinogenic substance that produces marked perceptual alterations.

Hallucinogenic drugs affect an individual’s perceptions in a different manner than other drugs affect perception of the environment. Hallucinogenic drugs produce experiences that are not consistent with reality, such as hallucinations (seeing, hearing, feeling, smelling, or even tasting things that are not really there), synesthesias (having mixed perceptual experiences, such as believing that one can see sound or hear colors), and the development of delusional behaviors. The dissociative aspect of PCP also represents an alteration in perception, such that one begins to feel that they are not real, that they are leaving their body, or that things around them are not real.

PCP use peaked in the 1970s and 1980s, according to the DEA. Even so, PCP is still a significant drug of abuse and classified as a Schedule II controlled substance, designating that its distribution is tightly controlled due to its potential to be abused and the extreme effects the drug produces. The drug can be snorted, injected, or smoked in cigarettes or cannabis products.

The research on the mechanism of action of PCP indicates that the drug has a very complicated mechanism of action, and its use alters the functioning of several different neurotransmitters in the brain. In addition, the full mechanism of action for PCP is still not clearly understood. It is hypothesized that:

  • PCP has an inhibitory effect on the neurotransmitter NDMA (N-methyl-D-aspartate), an important excitatory neurotransmitter that is involved in many different functions, including learning and memory, perception, and attention.
  • PCP affects the D2 dopamine receptor, which is a receptor that is also implicated in psychotic behaviors, such as in individuals with schizophrenia. Its actions on dopamine may explain some of its hallucinogenic effects.
  • PCP inhibits the effects of the neurotransmitter acetylcholine, which is involved in movement and memory.
  • PCP has an effect on certain serotonin receptors.
  • PCP facilitates the actions of endorphins and enkephalins, which are involved in diminishing the experience of stress, exertion, and pain. PCP was originally designed to be an anesthetic, and these actions may explain some of its anesthetic effects.

PCP Overdose

The National Institute on Drug Abuse (NIDA) states that the effects of PCP are dependent on the dose one takes.

  • Lower doses of PCP are the typical doses on the street, and they are usually between 1 mg and 6 mg. At these doses, the effects are similar to alcohol intoxication.
  • Moderate doses of PCP of between 6 mg and 10 mg. They produce significant psychosis, hyperactivity, and issues with irregular heartbeat, high blood pressure, muscle rigidity, and elevated temperature rates.
  • Very large doses exacerbate the above effects, and they are also likely to produce comatose states, catatonia, and seizures. Extremely large doses, above 200 mg, can be fatal.

Rosen’s Emergency Medicine: Concepts and Clinical Practice is an important guide to helping clinicians understand the effects of overdose related to numerous drugs of abuse. The signs of a PC overdose, according to this manual, may include any of the following:

  • Aggressiveness and/or agitation
  • Increased body temperature, high blood pressure, and irregular heartbeat
  • Loss of muscular coordination
  • An inability to control movements
  • A catatonic-like presentation where an individual does not move at all
  • Hyperactivity, if there is no catatonia
  • Nystagmus (uncontrolled side-to-side eye movements)
  • Severe hallucinations and delusions
  • Potential coma or unconsciousness
  • Potential seizures
Anyone who suspects that someone has overdosed on PCP should immediately contact emergency medical services by calling 911. If a person has no medical training, they should not attempt to get the individual any fluids or medications. One should attempt to control the individual by limiting any environmental stimulation, talking to them, and behaving in a calm and controlled manner until help can arrive. Eliminating environmental stimulation may include trying to block bright lights, minimizing noise, not touching the person, and moving slowly and deliberately. Do not approach someone who is extremely agitated; instead, keep your distance and monitor them until help arrives.

Treatment for PCP Overdose

There are no specific drugs that can be used to treat a PCP overdose. The treatment is often tailored to the individual’s presentation. If a person is aggressive, violent, confused, and hallucinating, they will often be given sedative medications (usually benzodiazepines) and may be put in restraints. Environmental stimulation should be kept to a minimum until the person calms down. This typically involves eliminating noise, turning off lights, and keeping visitors and medical personnel to a bare minimum. If the person is extremely hyperactive or agitated, they may need to be intubated in order to provide certain medicines.Once an individual is relatively well restrained, they can be given intravenous fluids and may be given activated charcoal, especially if it is suspected that the individual took the drug orally. Activated charcoal has been demonstrated to absorb PCP and lessen issues with potential renal failure in cases of PCP overdose. Individuals who have extremely high body temperatures may need to be cooled via the use of liquids and ventilation.

The clinicians will monitor the individual’s vital signs and treat any other symptoms. Seizure activity can be treated with benzodiazepines. If the individual’s behavior is overtly psychotic, antipsychotic medications may be used in some cases. IV fluids can help to flush the drug from the system. Medical personnel can also deal with complications, such as rhabdomyolysis, which is a condition that occurs when muscle tissue begins to break down and proteins are released in the blood.

This condition can be very serious and may have potentially fatal consequences.

A PCP overdose can be associated with numerous irreversible effects that can result in damage to numerous areas of the brain. The damage that occurs in these areas is often associated with reduced or blocked oxygen flow due to coma and decreased breathing, as a result of hyperthermia, or as a result of seizure activity. Areas that use high levels of oxygen in their normal functioning are particularly vulnerable. This includes damage to the frontal and temporal areas of the brain that are involved in attention, problem-solving, and learning and memory. Other areas of the brain that may be damaged as a result of a PCP overdose include the cerebellum, a structure at the posterior portion of the brain that is involved in movement and certain aspects of thinking and reasoning.

Some individuals may continue to display psychotic behaviors for a significant length of time following an overdose of PCP. These individuals may need long-term treatment for this behavior.  Individuals who continue to display psychotic behaviors after a PCP overdose and had no prior history of psychosis may have damaged certain areas of the brain that are involved in perception and reasoning. Other organs, such as the heart, liver, and kidneys, can also suffer irreversible damage as a result of reduced blood flow and oxygen.

Follow-up care typically includes referring the individual for substance use disorder treatment, continued outpatient therapy, the use of benzodiazepines to avoid seizures, and the continued use of antipsychotic medications as needed. Because an individual who has overdosed on PCP is at extreme risk for even more severe and potentially permanent effects if they continue to use the drug, it is extremely important that every effort be made to involve them in a formal substance use disorder treatment program. This includes helping the individual avoid use of other drugs of abuse as the damage that may have occurred as a result of a PCP overdose may leave them very vulnerable to future damage from other substances.

Last Updated on February 3, 2020
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