The Medical Research Council is providing nearly £1m to fund a clinical trial to assess the therapeutic effect of cannabis extract in multiple sclerosis. The MRC announced on December 13 that it has approved a grant of £950,000 to Dr John Zajicek (consultant neurologist, Derriford hospital, Plymouth) to undertake a three-year study. The double-blind, randomised trial will follow a protocol developed earlier this year by a Royal Pharmaceutical Society working party (PJ, January 16, p69).

Marinol capsules - one of the trial preparations

Dr Zajicek will recruit 660 patients with multiple sclerosis from across Britain who have significant spasticity in some of their leg muscles. Patients will receive one of three treatments, as oral capsules (see Panel): extract of cannabis (Cannador), tetrahydrocannabinol or THC (Marinol), or placebo. Dr Zajicek said: "We hope the study will provide definite scientific evidence about whether or not taking cannabis is helpful to people with multiple sclerosis."
Professor Tony Moffat (chief scientist, Royal Pharmaceutical Society) said that it was important to see whether Cannador worked and, if so, whether its effects, both therapeutic and unwanted, were the same as those of THC. One possibility, he said, was that other materials in the Cannador plant extract could mask the psychoactive effects of THC, while still allowing beneficial effects on muscles. Professor Moffat said that his belief, from the literature, was that cannabidiol, not THC, would be the therapeutically active agent in multiple sclerosis.
The MRC trial is separate from work being carried out by GW Pharmaceuticals, a commercial organisation, which is also developing cannabis-based products, using sublingual drops and sprays and a nebulised formulation (PJ, November 20, p811). GW's phase II studies, which are expected to start next year, will include patients with multiple sclerosis.
The Society's working party also drew up a protocol for a second trial, to investigate the effect of cannabis in treating acute pain. This trial is not yet funded but is to be discussed by the MRC next spring.

Patients will be randomised to receive one of three different treatments:

• Cannador - capsules containing extract of cannabis plant, standardised to contain 2.5mg tetrahydrocannabinol (THC). The cannabis for this product has been grown in Switzerland under special licence and is being put into capsules in Germany. The production of the capsules has been organised by the European Institute for Oncological and Immunological Research in Berlin
• Marinol - capsules containing pure THC 2.5mg. Produced by Unimed Pharmaceuticals in the US and licensed in the US for treatment of nausea in patients receiving cancer chemotherapy and for appetite enhancement in AIDS patients. Can already be used in the UK on a named-patient basis
• Placebo capsules

The European Institute for Oncological and Immunological Research and Unimed Pharmaceuticals are both supplying capsules for the trial free of charge.