Phencyclidine (1-[1-phenylcyclohexyl]piperidine monohydrochloride), commonly referred to as PCP, was synthesized in the late 1950s. It is an arylcyclohexylamine that was the first of a new class of general anesthetics known as cataleptoid anesthetics or dissociative anesthetics. Phencyclidine can be manufactured easily in unsophisticated laboratories from simple materials. Ketamine, an arylcycloalkylamine related to phencyclidine, is less potent and shorter acting and is still used as a dissociative anesthetic in humans (Chen et al. 1959), in addition to its illicit use as a drug of abuse. This section focuses on ketamine intoxication, abuse, and dependence. For more information on the recreational use of ketamine, the reader is referred to McDowell's discussion of club drugs in the final subsection of Chapter 15.