|Summary sheet: Ketamine|
|Common names||Ketamine, K, Ket, "Special K", Ketaset, "Vet/Horse/Dog tranquilizer", Ketanest|
|Routes of Administration|
Ketamine (also known as ket, K, "Special K", kitty, horse/dog/vet tranquilizer, among others) is a dissociative substance of the arylcyclohexylamine class that produces dissociative, anesthetic, and hallucinogenic effects when administered.
Ketamine was originally developed as a medicine in 1965 as a derivative and successor to PCP, the modern world's first synthetic general anesthetic agent.
Like other dissociative substances of its class such, as methoxetamine and phencyclidine (PCP), it is primarily sought by recreational users for its ability to induce a hallucinogenic "out of body" state referred to as "dissociative anesthesia" (although the extent to which this occurs is highly dose-dependent).
Ketamine is widely used in human and veterinary medicine, primarily for the induction and maintenance of general anesthesia for surgical procedures. Other applications of ketamine include sedation and anesthesia in intensive care situations, particularly in emergency medicine, and in the treatment of bronchospasm (i.e. a sudden constriction of the muscles in the walls of the lungs bronchioles).
While possessing recreational properties that led to its rise in popularity in the 1970s, it remains a core medicine in the World Health Organization’s “Essential Drugs List”, a list of the safest and most effective drugs needed in a modern health system. In addition to its widespread use as a licit medicine, ketamine is also commonly used today for recreational purposes and more rarely and controversially, as an entheogen.
- 1 History and culture
- 2 Chemistry
- 3 Pharmacology
- 4 Subjective effects
- 5 Medical uses
- 6 Toxicity and harm potential
- 7 Legal status
- 8 See also
- 9 External links
- 10 Literature
- 11 References
History and culture
This History and Culture section is a stub.
As such, it may contain incomplete or wrong information. You can help by expanding it.
Ketamine was invented as CL369, and it was referred to as CI 581 (clinical investigation 581) during development at Parke-Davis.
Ketamine, or (RS)-2-(2-Chlorophenyl)-2-(methylamino)cyclohexanone, is a member of the arylcyclohexylamine chemical class. Arylcyclohexylamines are named for their structures which include a cyclohexane ring bound to an aromatic ring along with an amine group. Ketamine is comprised of a phenyl ring with a chlorine substituent at R2 bonded to a cyclohexane ring substituted with an -Oxo group (cyclohexanone). An amino methyl chain (-N-CH3) is bound to the same location (R1) of the cyclohexanone ring.
Ketamine is a chiral molecule and is typically produced as a racemate, although enantiopure versions such as esketamine (S-ketamine) and arketamine (R-ketamine) are sometimes used in both licit and illicit contexts.
Ketamine acts as a non-competitive NMDA receptor antagonist. NMDA receptors allow for electrical signals to pass between neurons in the brain and spinal column; for the signals to pass, the receptor must be open. Dissociatives close the NMDA receptors by blocking them. This disconnection of neurons leads to loss of feeling, difficulty moving, and eventually the notorious state known as the “K-hole”.
At high, fully anesthetic level doses, ketamine has also been found to bind to μ-opioid receptors type 2 in cultured human neuroblastoma cells without agonist activity and to sigma receptors in rats. Also, ketamine interacts with muscarinic receptors, descending monoaminergic pain pathways and voltage-gated calcium channels. At subanesthetic and fully anesthetic doses, ketamine has been found to block serotonin depletion in the brain by inhibiting 5-HT receptors rather than through monoamine oxidase inhibition.
The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. The listed effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances and are more likely to induce a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.
- Spontaneous bodily sensations - The ketamine "body high" is a sharp, pleasurable tingling sensation which is location specific to the hands, feet and head. This regularly results in an out-of-body sensation or a general disconnection between the mind and body, which can be accompanied by states of euphoria.
- Physical euphoria - This results in feelings of physical euphoria which range between mild pleasure to powerfully all-encompassing bliss.
- Perception of bodily lightness - This creates the sensation that the body is floating and has become entirely weightless. This effect is oddly stimulating and encourages physical activities at low to moderate doses by making the body feel light and effortless to move.
- Changes in felt bodily form
- Changes in felt gravity
- Motor control loss - A loss of gross and fine motor control alongside balance and coordination is commonly produced by ketamine and becomes especially strong at higher dosages. This means that one should be sitting down before the onset (unless experienced) in case of falling over and injuring oneself.
- Tactile suppression - This partially to entirely suppresses one's sense of touch, creating feelings of numbness within the extremities. It is responsible for the anesthetic properties of this substance.
- Pain relief
- Optical sliding
- Dizziness - Although uncommon, some people report dizziness while under the influence of ketamine.
- Increased salivation
- Nausea - Ketamine at high doses can sometimes result in nausea and vomiting at the peak of the experience. For most people, this is not as unpleasant as they might expect due to the accompanying disconnection from the physical senses.
- Watery eyes - This usually only occurs when the substance is insufflated.
- Decreased libido
- Gustatory hallucination
- Orgasm suppression
- Physical autonomy
- Double vision - This component is prevalent at moderate to heavy doses and makes reading impossible unless one closes an eye.
- Pattern recognition suppression - This effect generally occurs at higher doses and makes one unable to recognize and interpret perceivable visual data.
- Acuity suppression
- Frame rate suppression
The visual geometry produced by ketamine can be described as very brightly colored in scheme when compared to that of other, less visually disconnecting dissociatives like MXE, but not as complex the geometry capable of being produced by DXM or any psychedelic. It does not extend beyond level 4 and can be comprehensively described through its variations as simplistic in complexity, algorithmic in style, synthetic in feel, unstructured in organization, dimly lit in lighting, multicoloured in scheme, glossy in shading, soft in edges, large in size, fast in speed, smooth in motion, equal in rounded and angular corners, immersive in its depth and consistent in its intensity.
At high doses, ketamine can produce a full range of high level hallucinatory states in a fashion that is less consistent and reproducible than that of many commonly used psychedelics. These effects include:
- Internal hallucination (autonomous entities; settings, sceneries, and landscapes; perspective hallucinations and scenarios and plots) - This effect can be comprehensively described through its variations as delirious in believability, fixed in style, equal in new experiences and memory replays in content, autonomous in controllability and solid in style.
- External hallucination (autonomous entities; settings, sceneries, and landscapes; perspective hallucinations and scenarios and plots) - This effect can be comprehensively described through its variations as delirious in believability, autonomous in controllability and solid in style. The most common theme for this effect to follow is one of experiencing and talking to friends when they are not actually present.
The cognitive effects of ketamine are often described as particularly forceful towards introspection and with a more analytical thought process when compared to that of other dissociatives such as DXM or MXE. These effects can be broken down into several separate subcomponents which are listed and described below:
- Analysis suppression
- Anxiety suppression
- Compulsive redosing
- Conceptual thinking
- Déjà vu
- Dream potentiation
- Ego inflation
- Focus suppression
- Immersion enhancement
- Increased music appreciation
- Memory suppression
- Personal bias suppression
- Spatial disorientation
- Suggestibility enhancement
- Thought deceleration
- Time distortion
Anecdotal reports which describe the effects of this compound within our experience index include:
Additional experience reports can be found here:
It has been demonstrated that ketamine, even if taken in small doses, is effective for patients suffering from chronic depression and bipolar disorder. Studies have shown that the effect of the drug is immediate or within 2 hours and consistent in relieving a patient’s depressive and/or suicidal symptoms, lasting up to 3 days after a single dose. In comparison, common antidepressants, such as Prozac, are entirely ineffective for 40% of the population and can take weeks to show effects. This gives ketamine the potential to become an indispensable tool in the treatment of depression and bipolar disorder, which is currently being held back by institutionalized drug prohibition.
Ketamine is a racemate that comprises the R-(−)-ketamine enantiomer (arketamine) and the S-(+)-ketamine enantiomer (esketamine). Esketamine inhibits the reuptake of the dopamine transporter about 8-fold more potently than does arketamine, and so is about 8 times more potent as a dopamine reuptake inhibitor. Arketamine appears to be more effective as a rapid-acting antidepressant than esketamine.
A study conducted in mice found that ketamine's antidepressant activity is not caused by ketamine inhibiting NMDAR, but rather by sustained activation of a different glutamate receptor, the AMPA receptor, by a metabolite, (2R,6R)-hydroxynorketamine; as of 2017 it was unknown if this was happening in humans. Arketamine is a AMPA receptor agonist.
Ketamine psychedelic therapy (KPT) is used for preparation for death (thanatological, Death-Rebirth Psychotherapy)
Toxicity and harm potential
Fatal ketamine overdoses are particularly rare, but not unheard of. However, the exact toxic dosage is unknown.
The first large-scale, longitudinal study of ketamine users found that frequent ketamine users (at least 4 days/week, averaging 20 days/month) had increased depression and impaired memory by several measures, including verbal, short-term memory and visual memory. However, infrequent (1–4 days/month, averaging 3.25 days/month) ketamine users and former ketamine users were not found to differ from controls in memory, attention and psychological well-being tests. This suggests the infrequent use of ketamine does not cause cognitive deficits and that any deficits that might occur may be reversible when ketamine use is discontinued. However, abstinent, frequent, and infrequent users all scored higher than controls on a test of delusional symptoms.
Short-term exposure of cultures of GABAergic neurons to ketamine at high concentrations led to a significant loss of differentiated cells in one study, and non-cell death-inducing concentrations of ketamine (10 μg/ml) may still initiate long-term alterations of the dendritic arbor in differentiated neurons. The same study also demonstrated chronic (>24 h) administration of ketamine at concentrations as low as 0.01 μg/ml can interfere with the maintenance of dendritic arbor architecture. These results raise the possibility that chronic exposure to low, subanesthetic concentrations of ketamine, while not affecting cell survival, could still impair neuronal morphology and thus might lead to dysfunctions of neural networks. 
More recent studies of ketamine-induced neurotoxicity have focused on primates in an attempt to use a more accurate model than rodents. One such study administered daily ketamine doses consistent with typical recreational doses (1 mg/kg IV) to adolescent cynomolgus monkeys for varying periods of time. Decreased locomotor activity and indicators of increased cell death in the prefrontal cortex were detected in monkeys given daily injections for six months, but not those given daily injections for one month.
Studies have shown that the serotonin systems affected by such serotonergic drugs are linked to the NMDA/glutamate systems. Tests on rats indicate that 5-HT agonists like LSD and psilocybin can prevent neurotoxicity due to NMDA receptor antagonists.
Urinary tract effects
According to a recent systematic review, 110 documented reports of irritative urinary tract symptoms from ketamine dependence exist. Urinary tract symptoms have been collectively referred to as "ketamine-induced ulcerative cystitis" or "ketamine-induced vesicopathy" and they include urge incontinence, decreased bladder compliance, decreased bladder volume and painful haematuria (blood in urine).
The time of onset of lower urinary tract symptoms varies depending, in part, on the severity and chronicity of ketamine use; however, it is unclear whether the severity and chronicity of ketamine use corresponds linearly to the presentation of these symptoms. All reported cases where the user consumed greater than 5 grams per day reported symptoms of the lower urinary tract.
It is strongly recommended that one use harm reduction practices when using this substance.
Tolerance and addiction potential
As with other NMDA receptor antagonists, the chronic use of ketamine can be considered moderately addictive with a high potential for abuse and is capable of causing psychological dependence among certain users. When addiction has developed, cravings and withdrawal effects may occur if a person suddenly stops their usage.
Tolerance to many of the effects of ketamine develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Ketamine presents cross-tolerance with all dissociatives, meaning that after the consumption of ketamine all dissociatives will have a reduced effect.
The following is a summary on the subject of ketamine dependence from the book Ketamine: Dreams and Realities by Karl Jansen, M.D. and Ph.D.:
- "With repeated long-term use, the effects may increasingly come to resemble a mixture of cocaine, opium, Cannabis, and alcohol, and become less and less psychedelic. While tolerance is rapid and marked, the ability to remember the experience also fades."
- "My view is that ketamine is far more likely to create periods of dependence than any other psychedelic drug. In my opinion, the group who lose control over their use is unlikely to exceed 15% of those who find the experience rewarding. This minority, however, is particularly likely to publish its stories; its members were often high profile mind-explorers before they became over-involved with ketamine (e.g. Moore, Lilly, and Turner). The risk is certainly very high in comparison with drugs such as LSD, DMT, and psilocybian mushrooms, but it is not more than half of those who like it."
- "A break of several years does not usually reverse tolerance to the psychedelic effects. The “no way back” situation applies to a wide range of drugs. Some heroin users are always trying to get back to the “first blush” but are unable to do so, even on near-lethal doses. Some persons with alcohol dependence can drink until they collapse without becoming merry. Some heavy MDMA users can still not find the “love effect,” even with 250 mg i.v. of dissolved pure powder. There are heavy cocaine and amphetamine users who, by the time they give up, many become paranoid each time they use rather than euphoric. After years of abstinence, 10 minutes into a relapse they become paranoid again. The experience will be closer to the last time they used rather than the first. In a similar manner, if heavy ketamine users take a break for a year and then resume, the effect is often the way they left it at the end rather than the way it was at the outset. It seems that there is no way for the journey to begin again at its original departure point. This persistent change has both a mental and a physical basis."
Although many psychoactive substances are safe on their own, they can become dangerous and even life-threatening when combined with other substances. The list below contains some common potentially dangerous combinations, but may not include all of them. Certain combinations may be safe in low doses of each but still increase the potential risk of death. Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.
- Stimulants - This combination can potentiate the anxiety-inducing, manic, delusional and disinhibiting aspects of dissociatives, particularly those without pronounced motor and consciousness-suppression components like ketamine as this can increase the likelihood of a panic event or psychotic episode.
- Prominent examples include PCP and its analogs 3-MeO-PCP, MXE, and the diarylethylamine dissociatives like diphenidine or ephenidine. There is also evidence that suggests that combining these two increases their neurotoxicity. Anecdotally, worsened comedowns are also commonly reported when these two classes of substances are combined.
- Depressants - Because both depress the respiratory system, this combination can result in an increased risk of suddenly falling unconscious, vomiting and choking to death from the resulting suffocation. If nausea or vomiting occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.
- Australia: Ketamine is a Schedule IV drug.
- Austria: Ketamine is legal for medical and veterinary use and illegal when sold or possessed without a prescription under the NPSG (Neue-Psychoaktive-Substanzen-Gesetz Österreich).
- Belgium: It is legal for medical and veterinary use and illegal when sold or possessed without a prescription.
- Brazil: The drug is legal for veterinary use and illegal when sold or possessed for human use.
- Canada: Ketamine is a Schedule I drug.
- China: Ketamine is a Schedule II drug.
- Czech Republic: It is legal for medical and veterinary use and illegal when sold or possessed without a prescription.
- Denmark: It is legal for medical and veterinary use and illegal when sold or possessed without a prescription.
- France: Ketamine is a Schedule IV drug.
- Germany: It is legal for medical and veterinary use and illegal when sold or possessed without a prescription.
- Hong Kong: Ketamine is a Schedule I drug.
- Malaysia: The possession and sale is illegal.
- Mexico: Ketamine is a Category 3 drug.
- New Zealand: Ketamine is a Class C drug.
- Norway: Ketamine is a Class A drug.
- Singapore: Ketamine is a Class A drug.
- Slovakia: Ketamine is a Schedule II drug.
- South Korea: The possession and sale is illegal.
- Sweden: Ketamine is a Schedule IV drug.
- Taiwan: Ketamine is a Schedule III drug.
- United Kingdom.: Ketamine is a Class B drug.
- United States.: Ketamine is a Schedule III drug.
- Interview with a Ketamine Chemist (VICE)
- The Experimental Ketamine Cure for Depression (VICE)
- Ketamine: Dreams and Realities (Jansen 2000, 2004)
- Durieux, M., & Kohrs, R.T. (1998). Ketamine: teaching an old drug new tricks. Anesthesia and Analgesia, 87 5, 1186-93. PMID: 9806706
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- Morris, H., & Wallach, J. (2014). From PCP to MXE: A comprehensive review of the non-medical use of dissociative drugs. Drug Testing and Analysis, 6(7–8), 614–632. https://doi.org/10.1002/dta.1620
- Bergman, S. A. (1999). "Ketamine: Review of its pharmacology and its use in pediatric anesthesia" - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2148883
- Peck, T. E.; Hill, S. A.; Williams, M. (2008). Pharmacology for anesthesia and intensive care (3rd edition). Cambridge: Cambridge University Press. p. 111
- WHO Model List of Essential Medicines | http://whqlibdoc.who.int/hq/2011/a95053_eng.pdf
- Pharmacology for Anesthetists, p255
- Interaction of ketamine with μ2 opioid receptors in SH-SY5Y human neuroblastoma cells | http://link.springer.com/article/10.1007%2Fs005400050035
- putative sigma1 receptor antagonist NE-100 attenuates the discriminative stimulus effects of ketamine in rats | http://onlinelibrary.wiley.com/doi/10.1080/13556210020077091/abstract
- Pharmaceutical Society of Australia. "2.1.1 IV general anaesthetics". Australian Medicines Handbook. 2011. Australian Medicines Handbook Pty Ltd. p. 13.
- Ketamine inhibits serotonin uptake in vivo. (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/6460944
- Ketamine Improves Bipolar Depression Within Minutes - http://www.medicaldaily.com/articles/10085/20120530/ketamin-bipolar-disorder-depression.htm
- Could A Club Drug Offer 'Almost Immediate' Relief From Depression? - http://www.npr.org/blogs/health/2012/01/30/145992588/could-a-club-drug-offer-almost-immediate-relief-from-depression
- Nishimura, M., & Sato, K. (1999). Ketamine stereoselectively inhibits rat dopamine transporter. Neuroscience Letters, 274(2), 131-134. PMID: 10553955. https://doi.org/10.1016/s0304-3940(99)00688-6
- Zhang JC, Li SX, Hashimoto K (2014). "R (-)-ketamine shows greater potency and longer-lasting antidepressant effects than S (+)-ketamine". Pharmacol. Biochem. Behav. 116: 137–41. doi:10.1016/j.pbb.2013.11.033. PMID 24316345.
- Tyler, M. W., Yourish, H. B., Ionescu, D. F., & Haggarty, S. J. (2017). Classics in Chemical Neuroscience: Ketamine. ACS Chemical Neuroscience. https://doi.org/10.1021/acschemneuro.7b00074
- Zanos, P., Moaddel, R., Morris, P. J., Georgiou, P., Fischell, J., Elmer, G. I., ... & Dossou, K. S. (2016). NMDAR inhibition-independent antidepressant actions of ketamine metabolites. Nature, 533(7604), 481-486. https://doi.org/10.1038/nature17998
- Yang, C., Zhou, W., Li, X., Yang, J., Szewczyk, B., Pałucha-Poniewiera, A., ... & Nowak, G. (2012). A bright future of researching AMPA receptor agonists for depression treatment. Expert opinion on investigational drugs. https://doi.org/10.1517/13543784.2012.667399
- Development of a rational scale to assess the harm of drugs of potential misuse (ScienceDirect) | http://www.sciencedirect.com/science/article/pii/S0140673607604644
- "Addiction Users Study: Consequences of chronic ketamine self-administration upon neurocognitive function and psychological well-being: a 1-year longitudinal study - http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2009.02761.x/abstract
- Low concentrations of ketamine initiate dendritic atrophy of differentiated GABAergic neurons in culture (ScienceDirect) | http://www.sciencedirect.com/science/article/pii/S0300483X07001138
- Neuroprotective NMDA antagonists: the controversy over their potential for adverse effects on cortical neuronal morphology (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/7976530
- Chronic ketamine exposure induces permanent impairment of brain functions in adolescent cynomolgus monkeys | http://onlinelibrary.wiley.com/doi/10.1111/adb.12004/abstract
- author=Arvanov V, Liang X, Russo A, Wang R |title=LSD and DOB: interaction with 5-HT2A receptors to inhibit NMDA receptor-mediated transmission in the rat prefrontal cortex | http://onlinelibrary.wiley.com/doi/10.1046/j.1460-9568.1999.00726.x/abstract
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- Ketamine-induced vesicopathy: a literature review | http://onlinelibrary.wiley.com/doi/10.1111/j.1742-1241.2010.02502.x/abstract
- Ketamine use: a review | http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2011.03576.x/abstract
- Ketamine: Dreams and Realities, p45
- [Ketamine: Dreams and Realities, p166-167]
- [Ketamine: Dreams and Realities, p181-182]
- Controlled Drugs and Substances Act of Canada
- Drugs penalties, GOV.UK, 3 September 2016. Retrieved on 25 November 2017.