Could a Horse Tranquilizer be a Last Resort Treatment for Severe Depression?

In a first of its kind study, researchers believe that a drug perhaps most well known as a powerful horse tranquilizer, that has been gaining ground as a potentially dangerous street drug, might have another medical use as a treatment for severe depression in humans.

The study, which was carried out by researchers at the Oxford Health NHS Foundation Trust together with the University of Oxford, found that the drug known as ketamine has several properties that make it viable as an antidepressant. What’s perhaps more interesting is that it works in a different way to other antidepressants, potentially offering a new tool in the fight against severe depression.

Previous research has shown that a single intravenous infusion of ketamine has a substantial power to reduce depression symptoms in some patients who had tried other treatments but found themselves resistant. As the drug, which is a licensed pain reliever and anesthetic, acted within hours of being administered, the researchers in this latest study wanted to gauge just how well it might work as a treatment regimen for patients with severe depression.

To study this, the researchers found a small group of 28 patients who all had treatment-resistant depression, and then set about treating them over a three week period with ketamine infusions. Some were given three infusions, others were given six. Patients were asked to report their moods and depression symptoms every day by text or email using standard scales to rate their feelings. The test participants were also assessed four to seven days after their final ketamine infusions were administered, and were monitored six months after that to see how they coped after the ketamine infusions and what long term effects it might have had.

The researchers found that among the test subjects, depression scores halved in eight patients. Four of those had scores that dropped so low they were considered to then be in remission. The positive effects lasted at least three weeks and around 15 percent of the test subjects found that it was two months before they had a depression relapse.

Perhaps just as importantly, the study, which is published this month in the Journal of Psychotherapy, found that the six infusions did not cause some of the side effects associated with the street version of this drug: there was no evidence of significant cognitive impairment or an impact on bladder function. However, some participants did experience the dissociative effects associated with the street drug while others experienced strong side effects like sickness and anxiety, which led two patients to drop out of the study. A further six failed to complete their treatment because they felt they weren’t getting any benefit.

Despite this, the researchers believe that ketamine could, if it proves itself in further trials, be a useful tool in combating the most serious forms of depression and might provide an alternative to the controversial electroconvulsive therapy which, while proven to help depression, comes with the severe side-effect of memory impairment.

Dr Rupert McShane, a consultant psychiatrist at Oxford Health who was involved with this research, is quoted as saying: “We’ve seen remarkable changes in people who’ve had severe depression for many years that no other treatment has touched. It’s very moving to witness. Patients often comment that the flow of their thinking seems suddenly freer. For some, even a brief experience of response helps them to realize that they can get better and this gives hope. ”

While Ketamine is often labelled as a horse tranquilizer, it is in fact used widely across the medical and veterinary field as an anesthetic and pain relief option. It is also illicitly used as an illegal drug and is classified as a Class B banned substance in the UK. Usually, recreational use sees patients take as much as several grams a day, which in turn leads to cognitive problems and a lack of bladder control. In some cases, ketamine use has proved fatal.

For comparison, the concentrations in this study were 80mg a dose, which is 80 thousandths of a gram, and the doses were given under controlled conditions in an environment that was monitored by health professionals. Needless to say, then, this study shouldn’t be seen as a green-light to self medicate with a dangerous street drug.

The researchers will now need to study ketamine’s effects in wider trials and also investigate different infusion regimens with the hope that by combining ketamine with other licensed drugs they will be able to improve its effects and potentially create a long term treatment solution for severe depression.

The very fact, however, that researchers have hit upon another way in which to treat people with severe and often debilitating depression is in itself an encouraging sign in a field of study where for a long time now major advances have seemed few and far between.

Photo credit: Thinkstock.


Janice Thompson
Janice Thompson3 years ago

Have you ever tried to swallow one of those.

Borg Drone
Past Member 3 years ago

Those things knock people for six. No, they are not the answer.

Pat P.
Pat P3 years ago

As much as I dislike the pharmaceutical industry, there are times when nothing else will work. If a person has had intractable depression for years, most likely, they have tried everything. If it is very severe, exercise and diet are just bandaids. Unless you have been in that situation, you, probably, know very little about it.
If nothing else has worked, some severely depressed people may be helped. Many will have nothing to lose, since they may commit suicide, otherwise.

Cynthia B.
cynthia l3 years ago

No way this seems very dangerous and another excuse for street drugs given the hallucinogenic properties

janice b.
jan b3 years ago

Getting rid of the problem(s) causing the depression is the best solution..

Alex H.
Alex H3 years ago

I have only one question about this awful drug,which no doubt makes billions for its manufacturer! Why do horses need to be given such a vile tranqilliser? Why are they in that much pain? Drug them up so that they run longer and do more damage to themselves?! What a vile world of animal abuse where animals are treated like this for gambling purposes!

Teresa W.
Teresa W3 years ago


Lucas Kolasa
Lucas Kolasa3 years ago


Lin M
Lin M3 years ago

I hope my depression never gets this bad. I do not want to take it.

Norma Villarreal
Norma Villarreal3 years ago

Ketamine on people? Another excuse to get overly medicated? Sounds risky to me.