IT is most widely used medically as a sedative or anaesthetic (and most notoriously as a “horse tranquiliser” – although it is used in veterinary medicine on various animals, as well as in equine surgery as an anaesthetic) and is known to produce out-of-body experiences for those who use it on the clubbing scene. But now researchers are looking at the potential for the drug ketamine to help those with depression who do not respond to conventional treatments.


Around one third of people who suffer from depression are classed as having “treatment-resistant depression” – meaning they have not responded to two trials of antidepressant treatments.


Ketamine has been gaining a reputation for providing relief for those who suffer from this type of depression. Still, uncertainty around its use and a lack of knowledge about its effects mean it has remained a controversial choice for establishing large clinical trials.


Now professor Stephen Lawrie, head of the Division of Psychiatry, from the Centre for Clinical Brain Sciences at the University of Edinburgh said “the time [was] absolutely ripe” for larger studies exploring ketamine’s uses.


He said that although it remained a “controversial area, and at best an experimental treatment, it is undoubtedly of interest”.


However, he urged caution, saying that those who said ketamine was already an “evidence-based treatment for depression would be wrong, and would be overstating the evidence”.


He continued: “In the context of depression, I’m keen to stress that the vast majority of people do respond to treatment with anti-depressants, but those with treatment-resistant depressions, or who have chronic depressions despite some benefit from treatment, are the people who will be supported by clinical trials. The more options we have for those people the better, and I think ketamine is currently one of many experimental approaches to this problem.”


He added: “I think if an individual patient has treatment-resistant depression and was offered ketamine as a treatment fully aware of the potential risks and made an informed decision, it’d be a legitimate and defensible approach on the part of the doctor.”


This week, scientists in Oxford, including the former head of the government’s advisory committee on drugs, Professor David Nutt, released a study into the ethics of trialling the drug, positing it as an “innovative” option for helping those with treatment-resistant depression. Basing its assertions on work done with 100 patients over six years, the group said that the drug could lead to rapid improvement in cases where all other avenues had been exhausted and had benefits lasting up to 14 days.


Dr Rupert McShane, a co-author of the study, also works a consultant psychiatrist at Oxford Health NHS Foundation Trust’s ketamine service, which offers a paid-for treatment to patients. “I have seen ketamine work where nothing has helped before,” he said.


McShane, however, warned that it should not be considered a “miracle” drug but instead urged that patients’ treatment should be in “specialist centres and formally tracked in national or international registries,” something which the study recommends.


When an approved medicine is used in an unapproved way – such as ketamine used as a depression treatment – it is referred to as “off-label,” meaning it is not yet regulated and no pharmaceutical company can market it.


Key areas requiring further investigation, which were highlighted in the study, include insufficient scientific knowledge, potential misuse, and uncertainty around long-term side effects.


Those in the Oxford study were treated in a clinical setting and intravenously, with much smaller doses than those who take it recreationally, however potential unwanted reactions include severe bladder issues and psychotic reactions. It is these issues which led the Royal College of Psychiatrists, in a response, to urge caution around the drug’s use.


Professor Allan Young, chairman of the College’s psycho-pharmacology special committee, said that there were still significant gaps in knowledge about the drug and “extensive research” was required before it could be recommended for clinical use for depression.


Similarly, a Scottish Government spokesman said: “Any prescribing or medication management guidance must be based on clinical advice and evidence-based.”