Cannabis-based treatments for multiple sclerosis might benefit patients despite the largest trial of such medicines failing to find objective evidence of improvement, researchers said last night.
A three-year study involving more than 600 patients revealed no reduction in muscle stiffness as measured by health professionals, yet most of those with the progressive nervous disorder felt cannabis had improved some of their symptoms.
Cannabis treatment did appear to cut slightly the time those who could walk took to cover small distances and the relapse rate among those who had the relapsing-remitting form of the disease, in which symptoms occur and then clear up for a period.
In addition, more patients on active treatment reported changes for the better relating to muscle stiffness, known as spasticity, pain and sleep than those on dummy treatment although the extra attention given patients on trials seems to have had an effect. Slightly more patients on the cannabis extract reported benefits than those on THC, an active compound found in cannabis.
The mixed results from the trial, the first independent study for any MS treatment for nearly 20 years, published in the Lancet medical journal, are unlikely to hinder the development of commercial drugs based on cannabis.
It involved giving patients capsules containing either cannabis extract, THC or a dummy treatment, although all patients continued to receive their normal medication for MS. John Zajicek, leader of the study funded by the Medical Research Council, said: "given how a patient feels is an important part of improving health, cannabis-based treatments may be of benefit."
The government's Medicines and Healthcare Products Regulatory Agency is evaluating the safety, quality and effectiveness of a mouth spray being developed by GW Pharmaceuticals.
Caroline Flint, drugs minister at the Home Office has promised the government will move quickly to "ensure ready and early availability of the drug as a prescribed medicine", once marketing approval is given.
Cannabis as a recreational drug is about to be downgraded from class B to C, and a small proportion of MS patients, estimates vary between 1% and 4% have risked arrest because they have believed it could relieve symptoms of their crippling condition. The MRC trial did not involve smoking cannabis because of it was considered unethical to expose patients to risks linked to smoking.
The researchers conceded more identifiable improvements in muscle stiffness might have been achieved through higher doses, although that would have meant more side effects.
The trial involved patients at 33 British centres. Dr Zajicek, consultant neurologist and assistant director of research at Plymouth Hospitals NHS trust, said the results presented "an interesting picture" but more research was needed using measure that "more adequately assess the effect of symptoms in chronic disease."
Mike Donovan, chief executive of the Multiple Sclerosis Society, said: "Current methods of measurement do not always detect significant benefits... On the evidence available, the society believes those who might benefit should be able to have treatment prescribed on the NHS."
Chris Jones, chief executive of the MS Trust, said it was frustrating that the results of the study were "somewhat equivocal", but it confirmed the strong anecdotal evidence of some patients benefiting.
