A common anaesthetic found to successfully treat depression has been hailed as “one of the most exciting discoveries” in recent years.

Ketamine, originally used in surgery to anaesthetise patients, has built up somewhat of a reputation as an illegal party drug.

But after a six-year trial, researchers have found that ketamine can work on depression “where nothing has helped before”.

The lead author, Dr Rupert McShane, believes that possibly “tens of thousands” of people could be helped by the class B drug.

He warns, however, that a national registry should be introduced to stop misuse of the substance.

“We think that patients’ treatment should be in specialist centres and formally tracked in national or international registries. This will help us to pick up any safety or abuse problems with longer term use and narrow down what dose, frequency, route and durations of treatment works best,” he said.

Around 101 people took part in the trial, with 42 responding positively to ketamine.

According to the report, one patient said ketamine “literally saved [his] life”.

“Subsequent ketamine treatment has enabled me to return to my job full-time. I still struggle at times but being able to work again has given me such a boost,” he said.

Commenting on the study, Professor Allan Young, from the Royal College of Psychiatrists, said: “Before ketamine can be recommended for use in clinical practice, extensive research is required to understand how to optimally use ketamine for treating depression.

“The Royal College of Psychiatrists has concerns for patient safety and hence recommends mental health practitioners to proceed with caution when treating patients with ketamine.”

Dr Paul Keedwell, Cardiff University psychiatrist, added: “Ketamine in the treatment of depression is one of the most exciting discoveries in psychiatry for years.

“However, more research is needed and having a registry allows researchers to share new findings, positive or negative.”