Ketamine is a dissociative anesthetic for use in human and veterinary medicine developed by Parke-Davis (1962).
Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA
receptor antagonist,[1] and, like other drugs of this class such as tiletamine, and phencyclidine (PCP), induces a
state referred to as "dissociative anesthesia.
As with other pharmaceuticals of this type, ketamine is used illicitly as a recreational drug, sometimes referred to
as Special K.
Ketamine has a wide range of effects in humans, including analgesia, anesthesia, hallucinations, arterial
hypertension, and bronchodilation.
It is primarily used for the induction and maintenance of general anesthesia, usually in combination with some
sedative drug.
Other uses include sedation in intensive care, analgesia (particularly in emergency medicine), and treatment of
bronchospasm.
Ketamine is a chiral compound.
Most pharmaceutical preparations of ketamine are racemic; however, some brands reportedly have (mostly undocumented)
differences in enantiomeric proportions.
The more active enantiomer, S-Ketamine, is also available for medical use under the brand name Ketanest S.

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 (referred
to as a "bump of K"), injected, or placed in beverages.
It is also possible to smoke the drug in a joint or pipe, usually mixed with marijuana and tobacco.
The smoke has a distinctive bitter taste but the effects of the high hit much faster than when insufflated or ingested.
Oral use usually requires more material, but results in a longer trip.
However, when administered orally, ketamine is rapidly metabolised to norketamine, which possesses sedating effects;
this route of administration is unlikely to produce a dissociative state characteristic of the k-hole
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.

Ketamine is also commonly combined with other drugs to enhance their effects.
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.
Unlike the other well known dissociatives PCP and DXM, ketamine is very short acting, its hallucinatory effects
lasting fifteen minutes or less when insufflated or injected, the total experience lasting no more than one or two
hours.
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, 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, relative scale, colour and durations/time, 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.
Ketamine produces a dissociative state, characterised by a sense of detachment from one's physical body and the
external world.
At sufficiently high doses (e.g. 150 mg intramuscular), users may experience what is coined the "K-hole", a state of
dissociation whose effects are thought to mimic the phenomenology of schizophrenia.
This may include distortions in bodily awareness, such as the feeling that one's body is being tugged, or is gliding
on silk, flying, or has grown very large or distended.
Users often report feeling more skeletal or becoming more aware of their bones - the shape of their hands is also
often of interest.
Users may experience worlds or dimensions that are ineffable, all the while being completely unaware of their
individual identities or the external world.
Users may feel as though their perceptions are 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.