By Dr. Jim Joyner | Published in Outcome Resources A new cannabis extract, Sativex, is undergoing phase III clinical trials in the U.S. for the treatment of severe neuropathic pain. It is approved in Canada for severe neuropathic pain due to multiple sclerosis (MS) and as an adjunct to opioid therapy in patients with advanced cancer (such as hospice patients.) The efficacy of Sativex was demonstrated in a double-blind placebo controlled trial in patients with cancer pain. Patients in the study had advanced cancer and were experiencing pain that was not responding to strong opioid such as morphine. In addition to the study medication, all patients remained on their existing opioid and other analgesic drugs during the trial. In this study, patients on Sativex showed a statistically significant improvement in pain relief, in comparison with placebo. The study further showed that in patients with advanced cancer who were already taking the strongest available pain treatments, more than 4 of 10 participants taking Sativex were able to achieve a further clinically important reduction in pain. In a previous study of 350 patients, Sativex was deemed to be effective for the treatment of neuropathic pain and spasticity in patients with MS. The drug is believed to act via cannabinoid receptors in the CNS and in immune cells. Activation of these receptors within the pain pathways is known to reduce pain in relevant pain models. Side effects included nausea, fatigue, and dizziness which were rated mild to moderate. There is no evidence of a euphoric effect that is associated with marijuana use. It has a unique method of administration which consists of a metered dose spray under the tongue or inside the cheek. You may be hearing more about this unique drug as the phase III trials proceed.