Ketamine, in lower doses, can be used to treat people suffering from severe depression, a new study from Oxford University shows.

According to researchers at Oxford Health NHS Foundation Trust and the University of Oxford, controlled injected doses of the drug can reduce symptoms of depression in people who don't respond to other medication for the disorder.

The study was based on 28 patients who were given around 80 mg of ketamine in a controlled and monitored environment.  The patients received either three or six ketamine infusions lasting 40 minutes. Participants were also given cognitive tests to assess the brain function after drug use.

The team found that in people who responded to the treatment, the benefits of using the drug lasted between 25 days and eight months. Also, the drug in lower doses didn't cause any cognitive decline or bladder damage.

"Ketamine is a promising new antidepressant which works in a different way to existing antidepressants. We wanted to see whether it would be safe if given repeatedly, and whether it would be practical in an NHS setting. We especially wanted to check that repeated infusions didn't cause cognitive problems," explained principal investigator Dr Rupert McShane, at Oxford Health.

What is Ketamine?                                                                                       

The drug ketamine is a white, crystalline powder or clear liquid. It was developed in 1962 and was initially marketed as a general anesthetic. Ketamine hit the streets in 1970's and by early 1980's, several people across the United States began using the drug.

In higher doses the drug gives users an out-of-body experience. Other common symptoms include dizziness, muscle twitches and slurred speech.

Other Researchers have known Ketamine's potential for use in anti-depression treatment for quite some time now. Most people in the present study felt the 'dissociative' effects. However, these effects were short-lived. Also, patients did not feel euphoric with the treatment.

The team has currently given 400 infusions to 45 patients.

"Intravenous ketamine is an inexpensive drug which has a dramatic, but often short-term, effect in some patients whose lives are blighted by chronic severe depression," said Dr McShane. 'We now need to build up clinical experience with ketamine in a small number of carefully monitored patients. By trying different infusion regimes and adding other licensed drugs, we hope to find simple ways to prolong its dramatic effect."

The study is published in the Journal of Psychopharmacology and was funded by National Institute for Health Research (NIHR) for Patient Benefit Programme.