Overview
Ketamine was first synthesised in the early 1960s and, after the usual animal and preclinical trials, was first used as a general anaesthetic towards the end of the Vietnam War. It is also used as a general painkiller (notably in emergency departments) and as a sedative in hospital intensive care, and there is some evidence that it can be an effective bronchodilator in severe asthma. Because ketamine does not harm respiratory function, its use is widespread in the medical community. It is most commonly used in veterinary practice.
In Australia, ketamine is a prescribed medication. However, India and China produce vast quantities of the drug, so it is quite easily available over the internet.
Pharmacology
Ketamine is classed as a dissociative agent. It acts as an NMDA receptor antagonist and potentiates opioid receptor activity. It also acts at numerous other sites in the body, including opioid receptors and monoamine transporters. In a clinical setting it is used for a variety of conditions, including:
- induction and maintenance of general anaesthesia
- pain management, including analgesia in patients with respiratory compromise or hypotension
- asthma
- depression.
Ketamine can be absorbed subcutaneously (usually to induce analgesia), orally (often as lozenges or ‘gummies’ after initial subcutaneous use), intravenously, intramuscularly and topically, although intramuscular and intravenous use are preferred.
Metabolism
Ketamine has a short half-life in the human body (2 to 3 hours). The liver metabolises it extensively on first pass, converting it into dehydronorketamine (the principal metabolite) and norketamine, which are excreted in the urine. Its short half-life means the drug is difficult to detect if the sample is not taken soon after ingestion (within 48 hours).
Recreational use
There were documented cases of ketamine abuse by the early 1970s. As well as its obvious sedative effect, ketamine is noted for its hallucinogenic properties. Users have reported ‘seeing God’ and being ‘transported to another world’ (the ‘K-hole’ effect). It acts very quickly once ingested and is typically taken orally. Its hallucinogenic effects are much shorter than those of other hallucinogens such as LSD, typically lasting around 1 to 2 hours.
Ketamine is sold illegally on the street under various names, including ‘K’, ‘Special K’, ‘Cat Valium’ and ‘purple’. It is often snorted in powder form, drunk or smoked, while the liquid form is more often injected. It is usually taken on its own but may be combined with ecstasy (MDMA).
Prevalence
The 2010 National Drug Strategy Household Survey reported a prevalence of around 0.2% for the whole population, but use was substantially higher in specific subgroups. Ketamine abuse occurs mainly among late teens and young adults, who are predominantly male, with high levels of abuse among the gay community and the party-scene subculture.
The Victorian Random Roadside Oral Fluid Testing Survey detected ketamine use in about 1.5% of drivers tested in 2010.
Side effects
Ketamine is a relatively benign compound when taken in a medical setting. In recreational use, inconsistent quality and uncontrolled ingestion mean the side effects vary. They include arrhythmia, tachycardia, rashes, vomiting, anorexia, nausea and cystitis.
Long-term use and abuse has been linked to brain damage and fatalities. Emergence reactions, such as vivid hallucinogenic dreams and delirium, may occur in up to 10% of moderate to high dose use.
Summary
Ketamine is readily available in Australia, particularly in the party scene. Because the body metabolises it quickly, most use is by people in full-time employment who are aware of the limitations of the commonly used drug testing methods.
Source: Safe Work Laboratories.