A company-sponsored trial of GW Pharma’s cannabis-based medicine, Sativex, in Rheumatoid Arthritis patients, shows the drug works as a painkiller and may also slow disease progression, according to research published online in Rheumatology on Wednesday.

In the first ever controlled trial of a cannabis-based medicine (CBM) in Rheumatoid Arthritis, significant pain-relieving effects were observed and disease activity was significantly suppressed following Sativex treatment, according to researchers.

“Whilst the differences are small and variable across the population, they represent benefits of clinical relevance and show the need for more detailed investigation in this indication”, researchers led by the Royal National Hospital for Rheumatic Diseases, in Bath, England concluded.

Of the 56 patients in the five-week randomised study, 31 were given Sativex daily by fixed delivery oromucosal spray and 27 received placebo.

Each spray of Sativex delivers Tetrahydrocannabinol (2.7mg) and cannabidiol (2.5mg).

Assessment of pain on movement, pain at rest, morning stiffness and sleep quality was measured using a numerical scale, the Short-Form McGill Pain Questionnaire (SF-MPQ) and the DAS28 measure of disease activity.

The cannabis-based drug produced statistically significant improvements in pain of movement, pain at rest, quality of sleep, and disease activity.

Co-author Philip Robson, Director of Cannaboid Research Institute, Oxford told APM: “It’s a preliminary study but you would have to say it’s a promising start. Pain relief was over and above the standard treatment already being taken in a stabilised way.

The so-called DAS scale is supposed to reflect the inflammatory effect of the disease and this improvement might suggest that the drug is affecting the process of the disease, “although this remains very speculative,” Robson added.

The large majority of side effects were mild or moderate and the treatment group showed no serious adverse effects or withdrawals due to side effects.

Three patients (11 percent) withdrew from the placebo group after experiencing adverse events they associated with treatment.

Adverse events reported with CBM included mild dizzyness, light-headedness, and dry mouth.

The study was funded by GW pharmaceuticals, which with Bayer, has launched Sativex for multiple sclerosis patients in Canada but which has so far failed to secure marketing authorisation in Europe.