A new cannabis-based medicine is bringing hope to thousands of arthritis sufferers desperate for an end to their agony. People living with the crippling condition could be helped by a mouth spray called Sativex, which cut pain and improved sleep in a trial of 58 patients.The second treatment, a cocktail of two drugs called Enbrel and methotrexate, is already licensed and should be available within months. Sativex was designed to help multiple sclerosis patients and it will have to pass another trial and gain official approval before it can be made available to arthritis sufferers. Drug company GW Pharmaceuticals, which carried out the trial, is the only company to legally develop and produce cannabis-derived treatments. It grows about 40,000 cannabis plants a year at a secret site in the English countryside.