There have been two main investigators of cannabis based medicinal product and these are Dr. Zajicek and GW Pharmaceuticals. Dr. Zajicek published the results of his study in The Lancet in November 2003 (Cannabinoids for treatment of Spasticity and other symptoms related to multiple sclerosis (cannabis in multiple sclerosis (CAMS) study). The 3 year CAMS trial, involving more than 600 patients in the United Kingdom, has yielded no definitive verdict on whether the drug can ease the symptoms of multiple sclerosis. I am not aware of any other ongoing studies by Dr. Zajicek.
On 17 March 2006, GW Pharmaceuticals announced the preliminary results from a Phase III study of Sativex (cannabis based medicinal product) in the relief of spasticity in people with multiple sclerosis (MS). This study is a randomized, placebo controlled group study in 335 MS patients with spasticity. According to the GW website, this study is one of a number of Phase III studies which are currently taking place to support approval of Sativex across Europe in a range of targeted indications.