Cannabis 'helps rheumatoid arthritis'

Cannabis: More evidence of its therapeutic effects

Scientists believe an ingredient of cannabis greatly reduces the pain of rheumatoid arthritis and could provide a cheaper alternative to current anti-arthritis drugs.

Components of cannabis have long been known to affect the immune system but now it seems that one component, cannabidiol, can block the progress of arthritis without any intoxicating or psychoactive side effects.

Professor Marc Feldmann of the Kennedy Institute of Rheumatology, who led the work, believes that cannabidiol could become the basis for a cheap anti-arthritis pill.

He told BBC Radio 4's Today programme: "It's a constituent which has no properties on the brain - it's not psychoactive, it can't give you a high."

Rheumatoid-arthritis is the crippling inflammation of the joints caused when the bodies immune system turns on itself.

Rather than fighting infections, it attacks the lining of the joints causing swelling and great pain.

There are drugs available, but they are either highly expensive, or produce severe side-effects in many patients.

Human medical trials

The cannabis extract has only been tried in mice so far, as described in the Proceedings of the National Academy of Sciences.

However, Professor Feldmann says that this drug is as effective in mice as a far more expensive treatment that has to be taken by injection.

The next stage would be to conduct small scale human medical trials.

However, Professor Feldmann warned that it could be up to five years before the drug might be available, and that even finding sponsors for the research was difficult, given the associations with an illegal drug.

He said: "What we have found is that as soon as you mention cannabis a lot of companies get put right off and don't want to enter discussions.

"There is certainly a hurdle to be crossed in the development of this drug."

This research adds another potential use for cannabis derived drugs.

Other cannabis compounds are effective painkillers and research has suggested that cannabis might help people with multiple sclerosis.