What is it?
Ketamine is a powerful general anaesthetic that's used for operations on humans and animals.
It is also known as Ket, Horsey, K, Special K, Vitamin K
It is categorised as an hallucinogen.
What it looks like
When used as a medical anaesthetic, ketamine is a liquid, because this makes it easy to inject. 'Street' ketamine is normally a grainy, white powder - although sometimes it can come as tablets.
How it's taken
Ketamine can be swallowed, inhaled or injected.
The effects don't last long, but until they wear off, ketamine can cause a loss of feelings in the body and paralysis of the muscles. It can also lead to users experience 'out of body' experiences, numbness and hallucinations.
Ketamine is risky in a number of ways:
Ketamine is a Class C drug. This means that it's illegal to possess it, give it away or supply it. Possession can get you up to two years in prison and/or an unlimited fine. Supplying someone else, even your friends, can get you 14 years in jail and/or an unlimited fine.
The President of Colombia, Juan Manuel Santos, has used his Nobel Peace Prize acceptance speech to call for the world to "rethink" the war on drugs.
He said the zero-tolerance policy might be "even more harmful" than all the other wars being fought worldwide.Drugs workers fear a "bad batch of heroin" could have led to the deaths of at least seven drug users in recent weeks in the Gwent Police force area.
Drugs workers fear a "bad batch of heroin" could have led to the deaths of at least seven drug users in recent weeks in the Gwent Police force area.
According to NHS figures, 1,087 babies in England were affected by maternal use of drugs in 2014-15, while in Scotland 987 babies were affected.
The Metropolitan Police has said it will examine 58 GHB-related deaths, following the conviction of serial killer Stephen Port.
A leading police chief says recreational drug testing "may be very useful". Commander Bray is in discussion with the government about it.
Britain should follow America's lead and legalise cannabis, and rake in £1 billion a year in tax revenues
Marijuana legalization will unleash misery on Arizona, according to a wave of television ads that started rolling out across the state last month.
Police in Denmark have arrested a man and woman on suspicion of providing cannabis to cancer patients and people with other serious illnesses.
The National Drugs Helpline is a 24-hour, 7-days a week, free and confidential telephone service that offers advice and information for anyone.
It is run by the government agency, known as FRANK, created to provide drug support and advice for the public.
If you need emergency help, are worried about a friend or relative's drug use or want support coping with your own, contact FRANK on-line contact or by phone.
My supply of ketamine is under threat and you should be worried. I'm not a drug addict. I'm an anaesthetist, and to me ketamine is medicine.
In rural hospitals in Nigeria, injecting the drug is essential for safe ceasareans, and to insert IVs for fluids and attach monitors to children without a struggle. It can be used for preventing pain. Some colleagues even advocate the use of oral ketamine for procedures in the accident and emergency department.
A substance produced after taking the drug ketamine could be used to create a fast-acting anti-depressant without its harmful side-effects, say scientists.
Ketamine, banned in the UK in 2006, initially used as a horse tranquiliser, is now better known for clubbing and date-rape. Clinical trials have shown it can relieve depression faster than commonly prescribed drugs, but it also created the dissociative, euphoric and addictive properties that made it an illegal drug.
Ketamine hydrochloride is a synthetic dissociative anaesthetic, synthesized in the 1960s for medical use, and used medicinally during the Vietnam war. It is usually consumed by snorting a white crystalline powder, at lower doses than when used as an anaesthetic. However it can also be injected, or smoked.
When ketamine is snorted, it gets into the blood stream quickly, and intoxication effects occur soon after it's taken. At low doses it raises heart rate.
Ketamine is an anaesthetic that has become a popular recreational drug. Last year, in an attempt to reduce recreational use, the UK government decided to ban all ketamine-like drugs and put ketamine under greater controls.
These changes were opposed by scientists who saw them as anti-scientific, and by doctors and vets who feared that the controls would reduce ketamine use with increase in patient suffering. Our fears turned out to be true.
A new study claims that the antidepressant effect of ketamine is caused by the metabolic breakdown of the drug, not the drug itself.
The study found that a compound called hydroxynorketamine was responsible for a lift in mood in mice given ketamine. The metabolite is a product of the molecular breakdown of ketamine and when given this metabolite, mice did not experience any of the side effects associated with ketamine.
New types of drugs for schizophrenia, depression and other psychiatric disorders are few and far between - and a number of companies have scaled back or dropped development of this class of pharmaceuticals. One exception stands out. Ketamine, the anesthetic and illegal club drug, is now being repurposed as the first rapid-acting antidepressant drug and has been lauded as possibly the biggest advance in the treatment of depression in 50 years.
When it first took hold in Britain, it was closely associated with dance music, but it has spread to the mainstream, taken at parties and in homes in cities, towns and villages across the country.
Ketamine is an anaesthetic with hallucinatory properties. Users feel detached from their body and surroundings. Surgeons in Leeds, London and Bristol say there are a growing number of people struggling with severe side effects.
Scientists believe that a radical treatment involving the tranquilliser ketamine could help overcome alcohol addiction by "erasing" drink-related memories.
Psychologists based at University College London are testing whether a one-off dose of the drug could help hazardous drinkers who are trying to reduce their alcohol intake. Alcohol addiction is notoriously difficult to treat, and there are few effective therapies available.
When Vicky and Ross woke on Wednesday 2 March, they had no reason to think the day would not be like any other. They were at their flat in Geneva and their first thought was for their children in London, Tommy, 23, and Louise, 21.
Ross set off for work, and Vicky prepared for her daily routine. Everything seemed normal. Then, just before his 8.30am meeting, Ross's phone rang with the news that Louise was dead after taking ketamine.