Ketamine is a general dissociative anesthetic for human and veterinary use. Its hydrochloride salt is sold as KetanestŪ, KetasetŪ and KetalarŪ. Pharmacologically it is very similar to Dextromethorphan and phencyclidine (PCP).
Ketamine was first used on American soldiers during the Vietnam War, but is often avoided now because it can cause unpleasant out of body experiences. It is still used in human medicine as a first-choice anesthetic for victims with unknown medical history (e.g. from traffic accidents), in podiatry and other minor surgery, and occasionally for the treatment of migraine.
In veterinary medicine, ketamine is often used for its anaesthetic and analgesic affects on cats, dogs, rabbits, rats, and other small animals. Veterinarians often mix ketamine with sedative drugs. Cats, in particular, usually receive ketamine with acepromazine and torbugesic in a mixture called KAT. Ketamine is sometimes used with horses and other large animals, but it has less effect on bovines.
Ketamine may be used in small doses (0.1 - 0.5 mg/kg/hr) as an analgesic, particularly for the treatment of pain associated with movement and neuropathic pain. It has the added benefit of counter-acting spinal sensitization or Wind-up phenomena experienced with chronic pain. At these doses, the psychotropic side effects are less apparent and well managed with benzodiazepines. It is a co-analgesic, requiring concomitant low-dose opioid to be effective.
Ketamine depresses respiratory and circulatory functions less than other anesthetics do. When used in anesthetic doses, it sometimes stimulates the circulatory system rather than depresses it. It is sometimes possible to perform ketamine anesthesia without protective measures to the airways. Ketamine is also a potent analgesic and can be used in sub-anesthetic doses to relieve acute pain; however, its psychotropic properties must be taken into account.
There is research going on in its usefulness in pain therapy and for the treatment of alcoholism and heroin addiction.
Ketamine is a Schedule III drug in the United States, and is used in many other countries, such as Mexico. Patients sometimes reported going into other worlds or seeing God while anesthetized: these unwanted psychological side-effects made ketamine less used.
Psychopharmacologically it is a non-competitive glutamate inhibitor at the NMDA receptors. These occur mainly in the hippocampal formation and in the prefrontal cortex , which explains its profound effects on memory and thought.
When used recreationally, it is known as K, Ket, Special K, or Vitamin K (not to be confused with Vitamin K).
Ketamine produces effects similar to PCP, and DXM. Like other disassociative anesthetics in low to upper middle dosages, its hallucinogenic effects are only seen in darkness or sensory deprivation. Users tout its trip as better than that of PCP or LSD because its overt hallucinatory effects are short-acting, lasting an hour or less. The drug, however, can affect the senses, judgment, and coordination for 18 to 24 hours. Ketamine sold on the streets comes from diverted legitimate supplies, primarily veterinary clinics, in either powdered or liquid form. In powdered form its appearance is similar to that of pharmaceutical grade cocaine and can be insufflated (snorted), placed in beverages, or smoked in combination with marijuana. Oral use usually requires more material. In therapeutic and psychedelic use the liquid is injected intra-muscularly, though for all intents and purposes, intravenous injection is impossible, as the user would be so quickly numbed as to be unable to finish the injection. The incidence of recreational ketamine use is increasing, and accounts of recreational ketamine use appear in reports of rave parties attended by teenagers and young adults. Ketamine was placed in Schedule III of the United States Controlled Substance Act in August 1999.
Like the other disassociative anesthics DXM and PCP, hallucinations caused by Ketamine are fundamentally different than caused by tryptamines and phenethlyamines. While at low doses the user must be in a dark room or have his eyes closed in order to see any hallucinations, at medium to high doses the effects are far more intense and obvious and include changes in the perception of distances and durations and the visual system being slow to update what the user is seeing.
Ketamine puts the user in a dissociated state, meaning that they are not connected to a sense of self, or to reality around them (See also Out of Body Experience). If a large enough amount is taken, they go through a "k-hole", and experience other worlds or dimensions that are impossible to describe in our language, while being completely unaware of their identity or the outside world. They feel as though their perception is located so deep inside their mind that the real world seems distant (hence the use of a "hole" to describe the experience). Often the user does not remember this part of the experience after they regain consciousness. The "re-integration" process is slow, and the user gradually becomes aware of things around them. At first they may not remember their name, or even know that they are a human, or what that means. Movement is extremely difficult, and they may not be aware that they have a body at all. It may be possible to use this state therapeutically, taking advantage of the dissociation and removing associations from one's brain. After the experience is over, some of these changes may remain.
Some drug users' first contact with ketamine is accidental, often from a pill sold as something else (commonly Ecstasy).
Ketamine is usually bought in powder form and snorted (taken nasally), though it can sometimes be bought in liquid form and then either cooked (heated to boil off the water and leave powder) or injected intramuscularly via a hypodermic needle. It is often taken with Ecstasy, due to its effect as an enhancer of the effects of other drugs.