New depression treatment discovered in UK

BRITISH scientists have created a potential new treatment for depression by combining a medication for pain relief with one for combating addiction.

CURRENT antidepressants, called SSRIs, increase the level of serotonin in the brain, although the exact mechanism by which they work is unclear.

Between 30 and 50 per cent of patients do not respond to the treatment, which can take several weeks to work and cause significant side effects, researchers say.

                               

A team at the University of Bath have now combined buprenorphine, a painkiller used post-surgery, and naltrexone, a drug used for treating addiction.

Their combination, which targets a different pathway in the brain to SSRIs, produced antidepressant-like responses in mice.

Researchers believe the time it would take to perform clinical trials and gain regulatory approval for the treatment could be reduced, as both drugs are already licensed for other conditions.

"Whilst SSRIs work for a lot of people, they can cause serious side effects and don't work for everyone," said Dr Sarah Bailey, senior lecturer at the University of Bath's Department of Pharmacy & Pharmacology.

"No new drugs for depression have been developed for decades ... so there's an urgent need to develop new treatments for this condition."

Buprenorphine reduces the patient's response to stress by blocking a receptor in the brain called the kappa opioid.

However, it also stimulates a related receptor called the mu opioid, which could cause addictive effects if taken long term or used by depressed patients.

To counter this, the researchers used the anti-addiction drug naltrexone, which blocks the mu receptor.

They found for the first time that in mice this combination gave an antidepressant effect.

"Our study shows that using a combination of naltrexone and buprenorphine gives an antidepressant effect in mice, but without the problems of addiction that could be caused by using buprenorphine alone," Dr Bailey said.