The question of whether ketamine is the same as PCP often arises due to their shared classification as dissociative drugs. While both substances induce a sense of detachment from one’s surroundings and pain, they are distinct compounds with different histories, medical applications, and legal standings. This article clarifies the unique characteristics of ketamine and phencyclidine, commonly known as PCP, to address this misunderstanding.
Understanding Ketamine
Ketamine is a dissociative anesthetic, initially developed in 1963 as a replacement for phencyclidine. It induces a trance-like state that provides pain relief, sedation, and amnesia, while generally preserving breathing and airway reflexes. This makes it particularly useful in trauma, emergency, and pediatric medical cases. Ketamine also stimulates heart function and increases blood pressure, and it can cause moderate bronchodilation.
Beyond its traditional use as a general anesthetic, ketamine has found applications in treating severe pain and treatment-resistant depression. In 2019, the S(+) enantiomer of ketamine, esketamine, received FDA approval as a nasal spray for treatment-resistant depression. Chemically, ketamine belongs to the arylcyclohexylamine class of drugs. It acts primarily as a noncompetitive antagonist at the N-methyl-D-aspartate (NMDA) receptor, blocking the influx of positive ions that depolarize nerve cells. Ketamine is classified as a Schedule III non-narcotic substance under the Controlled Substances Act in the United States, indicating an accepted medical use but also a potential for abuse leading to moderate or low physical dependence or high psychological dependence.
Understanding PCP
Phencyclidine, or PCP, was first developed in the 1950s as an intravenous anesthetic. Its medical use in humans was discontinued in 1965 due to severe side effects, including postoperative delirium with hallucinations, agitation, and irrational behavior. It was later restricted to veterinary use before its use in animals was also disallowed in 1978.
PCP is chemically known as 1-(1-phencyclohexyl)piperidine and belongs to the arylcyclohexylamine class of drugs. Its primary mechanism of action involves acting as a noncompetitive NMDA receptor antagonist, binding within the ion channel to inhibit receptor activity. This mechanism is responsible for its dissociative effects, which include distortions of sight and sound and feelings of detachment. PCP gained notoriety for its unpredictable and often dangerous effects, such as inducing a psychotic state resembling schizophrenia that can last for extended periods. It is classified as a Schedule II substance under the Controlled Substances Act, signifying a high potential for abuse and the possibility of severe psychological or physical dependence.
Key Distinctions and Shared Characteristics
Ketamine and PCP, while both classified as dissociative anesthetics and belonging to the arylcyclohexylamine chemical class, exhibit important distinctions. Both substances act as N-methyl-D-aspartate (NMDA) receptor antagonists, which is the primary mechanism behind their dissociative effects. They can both cause hallucinations, altered perceptions of time and space, and a feeling of detachment from one’s body or environment. Shared side effects can include nausea, vomiting, confusion, impaired motor function, and unconsciousness.
Despite these similarities, their medical utility diverges significantly. Ketamine maintains approved medical applications as an anesthetic and for certain mental health conditions, such as treatment-resistant depression. In contrast, PCP has no currently accepted medical use in the United States and its manufacturing for medical purposes has ceased. PCP is associated with a higher potential for unpredictable and aggressive behaviors, a risk not shared with ketamine. The effects of PCP also tend to last considerably longer, with active effects potentially lasting 4-8 hours and subjective effects up to 24-48 hours, whereas ketamine’s hallucinogenic effects usually last 30 to 90 minutes. Their legal classifications differ, with ketamine being a Schedule III controlled substance and PCP a Schedule II controlled substance, reflecting their varying potentials for abuse and dependence.
Why the Confusion Persists
The public’s confusion between ketamine and PCP stems from several interconnected factors. Both drugs are categorized as dissociative anesthetics, a broad classification that describes their ability to induce a sense of detachment. This shared classification often leads to an oversimplified understanding that equates the two substances. A significant contributing factor is their common chemical class, arylcyclohexylamines, and their similar mechanism of action as NMDA receptor antagonists. This underlying pharmacological relationship can obscure their individual properties in the public eye.
Historically, the development of ketamine shortly after PCP also played a role in the conflation. This historical proximity and the initial exploration of both for similar anesthetic purposes contributed to their association in public perception. Additionally, both drugs have been abused for their hallucinogenic properties, leading to their linkage in illicit drug narratives.