Ketamine has become a popular recreational drug, but prolonged use can lead to cognitive impairment and psychological addiction
Its low price, dissociative effect and quick response time have made ketamine an attractive alternative to party drugs such as cocaine and amphetamines. Its legal use is as an analgesic and anaesthetic in medicine, but ketamine has made its way into the black market as a recreational drug.
“From a pharmacological standpoint, ketamine’s best understood mechanism of action is as a non-competitive NMDA receptor antagonist,” explains Dr Craig Slattery of the Irish Society of Toxicology. “It is generally agreed that this mechanism underlies its sub-anaesthetic effects.
“The NMDA receptor is a glutamatergic receptor – glutamate is its primary natural activator. The receptors are located in both the central nervous system [CNS] and in the peripheral nervous system [PNS]. In the PNS, NMDA receptors appear to be very important in pain perception and transmission. In the CNS, NMDA receptors appear to be very important in long-term potentiation, a critical process in memory formation.
“Since ketamine is an antagonist at the NMDA receptor, that means it blocks these effects and processes, which may explain the effects on patients/abusers.”
Derivative of PCP
Originally developed in the 1960s as a derivative of phencyclidine, or PCP, it was intended for use as an anaesthetic.
“The first human trials were conducted in 1964 and showed that its shorter duration of action and less severe central nervous system effects made ketamine much more favourable than PCP as an anaesthetic,” explains Slattery.
While not widely used as an anaesthetic or analgesic, ketamine is on the World Health Organisation’s list of essential drugs. At low doses, it is a useful painkiller, particularly for chronic pain. At mid-level doses – but still at a sub-anaesthetic level – it can be used for more severe trauma pain. Then at high doses, ketamine is a full anaesthetic.
“Specifically, it is classified as a dissociative anaesthetic meaning that on going under and coming out of anaesthesia, patients report that the drug distorts their perception of sight and sound and it produces feelings of detachment from one’s self and the environment,” says Slattery.
“The main methods of use are snorting and swallowing,” says Slattery.
As a recreational drug, it is the dissociative state that is sought after. The sensation or psychological place a user goes to is often referred to as a “K-Hole” where very heightened sense combine with an extreme sense of decelerated physical motion.
‘Limbs feel numb’
One regular user, Dave*, described his experiences to The Irish Times: “Your limbs start to feel numb and things feel like they’re fading,” says Dave.
“Then transmissions from your brain to your limbs slow down so it feels like you’re moving and reacting very slowly to everything and everyone around you. If the dosage is high enough, your whole body can freeze and the mind goes on a voyage. Then there are other times where you may not freeze and you feel like Superman. It really depends on the quality, dosage and freshness of the drug.”
Its use in a recreational setting is a relatively new phenomenon in Ireland and research into side effects has only been carried out in a semi-anecdotal way.
“We have meta-analysis on the drug,” says Slattery. “All of our reports are from recreational users whose information has been gathered whenever you can get it, over, say, a 10-year period. Then we put all the findings together. It’s not ranked as highly in terms of scientific value but certain issues have frequently arisen.”
While not physically addictive, abusers can find themselves psychologically and socially dependent. “I tend to go on binges of it,” says Dave.
“I could do it every day for a month and then not touch it for two months after. When on a binge, I might take up to one gram a day, usually by snorting.”
According to the meta-analysis, the most frequent side effects of prolonged use cited are memory loss and urinary defects.
While not experiencing any urinary issues yet, Dave does admit to having impaired short-term memory function.
Damaging effects
While the amounts and way in which recreational users can have damaging effects, paradoxically the drug has also been found to be effective in the treatment of certain kinds of depression as well as weaning people off addictions to other substances.
“There’s currently a lot of interest in the role glutamate plays in depression and schizophrenia,” explains Prof Declan McLoughlin of the Institute of Molecular Medicine at Trinity College Dublin.
* Name has been changed
