Ketamine
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| Routes of administration | IV, IM, Insufflated, oral, topical |
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| Excretion | renal (>90%), urine |
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| ECHA InfoCard | 100.027.095 |
- For the collaborative acoustic project, see Katamine.
Ketamine is a general dissociative anaesthetic for human and veterinary use. Its hydrochloride salt is sold as Ketanest®, Ketaset®, and Ketalar®. Pharmacologically it is very similar to other dissociative anesthetics such as tiletamine and phencyclidine (PCP).
Ketamine is a chiral compound, with two distinct enantiomers. Most pharmaceutical ketamine preparations are racemic, however reportedly some brands have (mostly undocumented) differences in enantiomeric proportions.
History
Ketamine was first synthesized in 1962 in an attempt to find a safer anaesthetic alternative to Phencyclidine (PCP) which was more likely to cause hallucinations and seizures. The drug was first given to American soldiers during the Vietnam War, but today in the developed world its use on humans has been dramatically curtailed because of exaggerated concern about its potential to cause emergence phenomena including out of body experiences in clinical practice. However, it is still used widely in veterinary medicine, as a battlefield anesthetic, and in developing nations.
Ketamine's side effects eventually made it a popular psychedelic in 1965. The drug was used in psychiatric and other academic research through the 1970s, culminating in 1978 with the publishing of John Lilly's The Scientist, a book documenting the author's ketamine, LSD, and isolation tank experiments. The incidence of recreational ketamine use increased through the end of the century, especially in the context of raves and other parties. The increase in illicit use prompted ketamine's placement in Schedule III of the United States Controlled Substance Act in August 1999. In the United Kingdom, it became outlawed and labelled a Class C drug on January 1, 2006.[1] In Canada, as of August 31 2005, ketamine is classified as a Schedule I narcotic.
Medical use
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Since it suppresses breathing much less than most other available anaesthetics, ketamine is still used in human medicine as a first-choice anaesthetic for victims with unknown medical history (e.g. from traffic accidents), in podiatry and other minor surgery, and occasionally for the treatment of migraine. There is ongoing research in France, Russia, and the U.S. into the drug's usefulness in pain therapy and for the treatment of alcoholism and heroin addiction.
In veterinary medicine, ketamine is often used for its anaesthetic and analgesic effects on cats, dogs, rabbits, rats, and other small animals. Veterinarians often use ketamine with sedative drugs to produce balanced anaesthesia and analgesia, and as a constant rate infusion to help prevent pain wind-up. Ketamine is used to manage pain among horses and other large animals, though it has less effect on bovines.
Ketamine may be used in small doses (0.1–0.5 mg/kg/h) 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. Ketamine is a co-analgesic, requiring a concomitant low-dose opioid to be effective.
The effect of Ketamine as a depressant on the respiratory and circulatory systems is less than that of other anaesthetics. When used at anaesthetic doses, it will sometimes stimulate rather than depress the circulatory system. It is sometimes possible to perform ketamine anaesthesia without protective measures to the airways. Ketamine is also a potent analgesic and can be used in sub-anaesthetic doses to relieve acute pain; however, its psychotropic properties must be taken into account. Patients have reported vivid hallucinations, "going into other worlds" or "seeing God" while anaesthetized, and these unwanted psychological side-effects have reduced the use of ketamine in human medicine.
Experimental Antidepressant Use
The National Institute of Health News reports that a study of 17 patients led by Dr Carlos Zarate Jr. of the National Institute of Mental Health found that ketamine significantly improved treatment-resistant major depression within hours of injection. [1] The improvement lasted up to one week after the single dose. [2] The patients in the study were previously treatment resistant, having tried an average of six other treatments that failed. The importance of these findings was articulated by NIMH director Dr Thomas Insel: "To my knowledge, this is the first report of any medication or other treatment that results in such a pronounced, rapid, prolonged response with a single dose. These were very treatment-resistant patients." The researchers apparently attribute the effect to ketamine being an NMDA receptor antagonist. The study appears in the Archives of General Psychiatry. [3] Those findings of Zarate et al corroborate earlier findings by Berman et all. [4]
Treatment of Addiction
The Russian doctor Evgeny Krupitsky (who is Clinical Director of Research for the Saint Petersburg Regional Center for Research in Addiction and Psychopharmacology) has gained encouraging results by using ketamine as part of a treatment for alcohol addiction which combines psychedelic and aversive techniques [5]. This method involved psychotherapy, controlled ketamine use and group therapy, and resulted in 60 of the 86 alcoholic males selected for the study remaining fully abstinent. He has also treated heroin addicts and reached the conclusion that ketamine reduces the craving for heroin without any adverse reaction [6].
Neuropharmacology
Ketamine, like Phencyclidine, is primarily a non-competitive antagonist of the NMDA receptor, which opens in response to binding of the neurotransmitter glutamate. This NMDA receptor mediates the analgesic (reduction of pain) effects of ketamine at low doses. Evidence for this is reinforced by the fact that naloxone, an opioid antagonist, does not reverse the analgesia. Studies also seem to indicate that ketamine is 'use dependent' meaning it only initiates its blocking action once a glutamate binds to the NMDA receptor.
At high, fully anesthetic level doses, ketamine has also been found to bind to opioid mu receptors and sigma receptors. Thus, loss of consciousness that occurs at high doses may be partially due to binding at the opioid mu and sigma receptors.
Ketamine is racemic, and its R and S stereoisomers have different binding affinities: (S)-Ketamine has about four times greater affinity for the PCP site of the NDMA receptor than does (R)-Ketamine (in guinea pig brain). The S form also seems to be better at inducing the drowsiness than the R form.[2]
The effects seem to take place mainly in the hippocampal formation and in the prefrontal cortex. This evidence, along with the NMDA receptor's connection with the memory formation process, explains ketamine's profound effects on memory and thought. These effects inhibit the filtering function of the brain and may mirror the sensory overload associated with schizophrenia and near death experiences.
Recreational use
When used recreationally, ketamine can be known as K, Ket, Special K,Spesh, Vitamin K (not to be confused with the true vitamin K), Smack K, Kit-Kat, Keller, Barry Keddle, HOSS, The Hoos, Hossalar, kurdamin, kiddie, Wonk, Regreta and tranq.
Illicit sale
Ketamine sold illicitly comes from diverted legitimate supplies or theft, primarily veterinary clinics. In the US near its border with Mexico, the drug is most commonly acquired in Mexico, where it can be bought over the counter in veterinary clinics, and smuggled across the border.
In 2003, Operation TKO was a probe conducted by the U.S. Drug Enforcement Agency (DEA). As a result of operation TKO, U.S. and Mexican authorities shut down the Mexico City company, Laboratorios Ttokkyo, which was the biggest producer of ketamine in Mexico. According to the DEA, over 80% of ketamine found in the U.S. is of Mexican origin.[3]
Methods of use
Ketamine is sold in either powdered or liquid form. In powdered form, its appearance is similar to that of pharmaceutical grade cocaine and can be insufflated (snorted, also known as "taking bumps"), injected, or placed in beverages. Oral use usually requires more material, but results in a longer trip. The liquid can be heated to drive off the solvent (usually saline), leaving powder. In therapeutic and psychedelic use, the liquid is typically injected intramuscularly. Intravenous injection is uncommon (recreationally), though possible. It is essentially identical in effect to intramuscular injection, but leads to a much quicker onset — usually within 10 to 15 seconds of dosing. Additionally, intravenous injection tends to lead to a more sudden and marked respiratory depression, especially if the solution is injected at too high of a potency (too fast). These factors make intravenous self-injection dangerous.
Some drug users' first contact with ketamine is accidental, often from a pill sold as something else (commonly ecstasy). Ketamine is also commonly combined with other drugs to enhance their effects. There have been claims that ketamine has been used as a date rape drug because of the powerful dissociative effects.
Psychological effects
Unlike true psychedelics, ketamine is powerfully reinforcing to many users and compulsive use is frequently reported. Both ketamine pioneer John Lilly and pseudonymous author D.M. Turner reported experienced prolong periods of 'ketamine dependency,' and the latter drowned in a bathtub while on ketamine.
Ketamine produces effects similar to PCP and DXM. Like other dissociative anesthetics in low- to upper-middle dosages, its hallucinogenic effects are only seen against a background lacking sensory stimulation, such as darkness. Some users claim that a trip due to ketamine use is as good or better than that of PCP or LSD because its overt hallucinatory effects are short-acting, lasting an hour or less in most cases. Effects on the senses, judgment, and coordination, however, can last for 18 to 24 hours. Standing up and moving may be more dangerous than lying still in one place.
Like the other dissociative anaesthetics DXM and PCP, hallucinations caused by ketamine are fundamentally different from those caused by tryptamines and phenethylamines. At low doses a hallucinations are only seen when one is in a dark room with one's eyes closed, while at medium to high doses the effects are far more intense and obvious. These effects include changes in the perception of distances and durations as well as a slowing of the visual system's ability to update what the user is seeing. There are reports of high-dosage users being able to see their surroundings in two sharp images, as if the brain is unable to merge the images each eye is sending. Speech often sounds unintelligible and auditory hallucinations may occur.
Ketamine puts the user in a dissociated state, meaning that they are less connected to both a sense of self and the reality around them. If a large enough amount is taken, the user may go into or through a "K-hole", a state of wildly dissociated experience in which other worlds or dimensions that are difficult to describe with language are said to be perceived, all the while being completely unaware of one's individual identity or the outside world. A user may feel as though his or her perception is located so deep inside the mind that the real world seems distant (hence the use of a "hole" to describe the experience). Some users may not remember this part of the experience after regaining consciousness, in the same way that a person may forget a dream. The "re-integration" process is slow, and the user gradually becomes aware of surroundings. At first, a user may not remember his or her own name, or even know that they are human, or what that means. Movement is extremely difficult, and a user may not be aware that they have a body at all.
Ketamine in Media
- In the seventh episode of the first season of the American television series the Dead Zone, titled "Enemy Mind," the lead character, psychic Johnny Smith, accidentally inhales Ketamine in aerosol state, and the drug wreaks havoc with his "dead zone," the primary brain center for his psychic visions.
- In the last episode of the second season of the American televison series House, titled "No Reason," the lead character, Dr. Gregory House, is administered Ketamine to try to relieve the terrible leg pain he has been suffering throughout the course of the series. At the beginning of the third season, it seems that the Ketamine treatment has worked, though it is not clear for how long.
- In the sixth episode of the second season of I'm Alan Partridge, entitled "Alan Wide Shut", Alan Partridge attends a radio interview on a programme called Prayer Wave to promote his autobiography and has a surreal, barbed conversation with a woman called Kate Fitzgerald who is also promoting her autobiography. They discuss her ketamine use and move on to talk about Alan's addiction to chocolate, specifically Toblerone.
References
- ^ NIH. Experimental Medication Kicks Depression in Hours Instead of Weeks. NIH News, August 7, 2006
- ^ Khamsi, R. Ketamine relieves depression within hours. New Scientist, 08 August 2006.
- ^ Zarate CA Jr, Singh JB, Carlson PJ, Brutsche NE, Ameli R, Luckenbaugh DA, Charney DS, Manji HK. A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Archives of General Psychiatry, 2006 Aug;63(8):856-64. PMID 16894061.
- ^ Berman RM, Cappiello A, Anand A, Oren DA, Heninger GR, Charney DS, Krystal JH. Antidepressant effects of ketamine in depressed patients. Biol Psychiatry. 2000 Feb 15;47(4):351-4. PMID 10686270.
- ^ http://www.eleusis.us/resource-center/references/acamethod.php
- ^ http://www.eleusis.us/resource-center/references/ketamine-psychotherapy-heroin.pdf
See also
External links
- Erowid.org's Ketamine vault
- Erowid.org's John C. Lilly Vault
- TRIPproject.ca: Ketamine, harm reduction initiative
- The Guardian: Ketamine (29/12/05)
- Eleusis References on the uses of ketamine as an entheogen for treating alcoholism, the use of ketamine in psychiatry, and for treating drug addiction
- Radical Relief Use of ketamine as an agent to "reboot" the brain of a patient in chemically induced coma to greatly diminish chronic pain.
- Club drug finds use as antidepressant - Psychedelic ketamine hits the blues surprisingly fast; Nature.com