Chemicals found in cannabis have the potential to relieve pain and reduce joint inflammation in people suffering from osteoarthritis.
Compounds found in marijuana that were synthesised in a laboratory hold the potential to be developed into new drug therapies for the treatment of the condition that affects the joints.
Researchers from the Arthritis Research UK Pain Centre at the University of Nottingham have found that natural chemicals found in cannabis – or cannabinoids – can relieve pain in animals suffering from arthritis.
Until now their use has been limited because of the psychological side effects of the chemicals.
Around eight million people in the UK are affected by osteoarthritis, which occurs when the cartilage at the ends of bones wears away, causing pain and disability.
There are no drugs available that slow progression of the condition but a number of people with osteoarthritis are believed to use cannabis for pain relief, although under English law is not recognised as having any therapeautic value.
The US-based Arthritis Foundation said: "Research shows that, among other things, cannabis eases chemotherapy-induced nausea and loss of appetite, and relieves spasms in individuals with multiple sclerosis. Even so, pain relief is perhaps the most well-recognised and studied effect."
Research leader Victoria Chapman said that the team has been able to selectively target one molecule involved in the body's pain-sensing pathways with a compound called JWH133 – a cannabinoid molecule not derived from the cannabis plant.
Cannabinoids are also known to have anti-inflammatory effects and the team used the compound to reduce levels of inflammation in studies of osteoarthritis.
Drugs derived from cannabinoids could, therefore, have a duel benefit for the treatment of arthritis by reducing both pain and inflammation at the same time.
Chapman said: "This finding is significant, as spinal and brain pain signalling pathways are known to make a major contribution to pain associated with osteoarthritis. These new data support the further evaluation of the selective cannabinoid-based interventions for the treatment of osteoarthritis pain."
Prof Alan Silman, medical director of Arthritis Research UK, added: "Millions of people are living with the severe, debilitating pain caused by osteoarthritis, and better pain relief is urgently needed.
"This research does not support the use of recreational cannabis use. What it does suggest is that there is potential to develop a synthetic drug that mimics the behaviour of cannabinoid receptors without causing serious side effects."