What Are the Effects of PCP?

From National Institute on Drug Abuse

Updated September 07, 2009

PCP, developed in the 1950s as an intravenous surgical anesthetic, is classified as a dissociative anesthetic: Its sedative and anesthetic effects are trance-like, and patients experience a feeling of being “out of body” and detached from their environment.

In powdered form, the drug is sprinkled on marijuana, tobacco, or parsley, then smoked, and the onset of effects is rapid. Users sometimes ingest PCP by snorting the powder or by swallowing it in tablet form. Normally a white crystalline powder, PCP is sometimes colored with water-soluble or alcohol-soluble dyes.

When snorted or smoked, PCP rapidly passes to the brain to disrupt the functioning of sites known as NMDA (N-methyl-D-aspartate) receptor complexes, which are receptors for the neurotransmitter glutamate. Glutamate receptors play a major role in the perception of pain, in cognition – including learning and memory – and in emotion. In the brain, PCP also alters the actions of dopamine, a neurotransmitter responsible for the euphoria and “rush” associated with many abused drugs.

At low PCP doses (5 mg or less), physical effects include shallow, rapid breathing, increased blood pressure and heart rate, and elevated temperature. Doses of 10 mg or more cause dangerous changes in blood pressure, heart rate, and respiration, often accompanied by nausea, blurred vision, dizziness, and decreased awareness of pain.

Muscle contractions may cause uncoordinated movements and bizarre postures. When severe, the muscle contractions can result in bone fracture or in kidney damage or failure as a consequence of muscle cells breaking down. Very high doses of PCP can cause convulsions, coma, hyperthermia, and death.

PCP’s effects are unpredictable. Typically, they are felt within minutes of ingestion and last for several hours. Some users report feeling the drug’s effects for days. One drug-taking episode may produce feelings of detachment from reality, including distortions of space, time, and body image; another may produce hallucinations, panic, and fear. Some users report feelings of invulnerability and exaggerated strength. PCP users may become severely disoriented, violent, or suicidal.

Repeated use of PCP can result in addiction, and recent research suggests that repeated or prolonged use of PCP can cause withdrawal syndrome when drug use is stopped. Symptoms such as memory loss and depression may persist for as long as a year after a chronic user stops taking PCP.

PCP was used in veterinary medicine but was never approved for human use because of problems that arose during clinical studies, including delirium and extreme agitation experienced by patients emerging from anesthesia.

Effects of Long Term Use 26

• “Runs” – Chronic users may binge use PCP, taking it repeatedly for 2 or 3 days at a time without eating or sleeping, followed by a period of sleep. These runs may occur as many as four times in a month.
• Impaired memory
• “Flashbacks” similar to those experienced by chronic LSD users
• Persistent speech problems, such as stuttering, inability to articulate, or the inability to speak at all
• Chronic and severe anxiety and depression, possibly leading to suicide attempts
• Social withdrawal and isolation
• Toxic psychosis may appear in chronic users who do not have a prior history of psychiatric disturbances. The symptoms of toxic psychosis are aggressive or hostile behavior, paranoia, delusional thinking and auditory hallucinations.

PCP and Violence

Despite its reputation in the media as a drug that causes bizarrely violent behavior and gives users superhuman strength, research does not support the idea that PCP itself is the cause of such behavior and strength. Instead, those who experience violent outbursts while under the influence of PCP often have a history of psychosis or antisocial behavior that may or may not be related to their drug abuse.27