"Phencyclidine was investigated as an intravenous anaesthetic in the 1950s but was later withdrawn due to undesired hallucinogenic and delirium effects.34 Following the withdrawal of phencyclidine, ketamine was synthesized as an anaesthetic in 1962, patented in 1963 in Belgium and three years later in the United States. In the early 1970s, ketamine was marketed as a medical alternative to phencyclidine.
"The use of ketamine as a new psychoactive substance dates back to the 1980s and 1990s. At the international level, ketamine was subject to a series of risk assessments. The Expert Committee on Drug Dependence of the WHO pre-reviewed ketamine in 2003 and conducted a critical review in 2006. After reviewing the information contained before it, the Committee concluded that 'this information was not sufficient to warrant scheduling'.35 It also requested an updated version of the critical review to be presented at the next meeting of the Committee which was held in 2012. At that meeting, the Committee decided that 'bringing ketamine under international control is not appropriate.'36 At the level of European Union, in 2000, growing concern over the use of ketamine as a NPS prompted a risk assessment in the framework of the joint action on new synthetic drugs.37 The European Commission concluded that it was not appropriate to introduce control measures and recommended further monitoring of the use of ketamine."
UN Office on Drugs and Crime, "The Challenge of New Psychoactive Substances: A Report from the Global SMART Programme" (Vienna, Austria: UNODC Laboratory and Scientific Section, March 2013), p. 8.