Ketamine was first synthesised in 1962 and patented in Belgium in 1963.
As an anaesthetic and analgesic, ketamine has a recognised unique therapeutic
value in veterinary practice and, to a lesser extent, in human medicine.
For therapeutic purposes, ketamine usually is administered intravenously or
intramuscularly.

In recreational use, typical doses are: 75–125 mg intramuscularly or subcutaneously;
60–250 mg intranasally; 50–100 mg intravenously; and 200–300 mg
orally.

Ketamine is manufactured by the chemical industry for use in the manufacture
of pharmaceutical products which use as precursors cyclopentyl bromide,
o-chlorobenzonitrile and methylamine. Due to the complicated multi-step
synthesis, and the difficulty of purchasing the necessary precursors and
numerous solvents and reagents, ketamine sold illicitly for recreational use
appears to be mostly obtained by diversion of legitimate supplies of either
the bulk drug or of pharmaceutical preparations containing it.

Pharmaceutical products may be injected or may be modified by evaporation,
after which the resultant powder may be snorted in pure form or mixed with
other drugs and/or inactive components. In powder form, combination with
cocaine has been observed. In the form of tablets, the concentration of
ketamine and other substances is mostly unknown by users. These tablets are
sold as ‘ecstasy’ in some Member States. Other substances reported to be
present in tablets containing ketamine are pseudoephedrine, ephedrine,
caffeine, amphetamine, methamphetamine and MDMA. As the effects of
ketamine are dose-dependent, the fact that the amount of ketamine concentrated
in the powder (and a fortiori in fake ‘ecstasy’ tablets) is unknown poses
a risk in recreational use.

Preparations containing ketamine hydrochloride are used as an anaesthetic
and analgesic agent in human and veterinary medicine, with important clinical
applications in paediatric and ambulatory anaesthesia, treatment of burnwound
patients and for short anaesthetic procedures. However, the use of
ketamine for humans in the EU is restricted to special indications, due to the
occurrence of emergence reactions. Outside the EU, its ease of use gives
ketamine a major advantage under difficult circumstances (developing
countries and remote areas). Its use in veterinary anaesthesia, especially for
small animals, is widespread and considered by several Member States and
by the Federation of Veterinarians of Europe as indispensable in veterinary
medicine.