Published online 7 November 2003 | Nature | doi:10.1038/news031103-14

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Cannabis study shows small MS benefit

Multiple sclerosis patients report some relief in pot trial.

Clinical trials of cannabis-based medicines have been slow in coming.Clinical trials of cannabis-based medicines have been slow in coming.© alamy.com

Cannabis may soothe symptoms of multiple sclerosis, concludes the first large-scale clinical trial of the drug's perceived benefit to sufferers. Legally, the drug remains largely out of bounds.

The British study is the one of the strongest scientific endorsements of patients' anecdotal evidence that cannabis helps to relieve the pain of multiple sclerosis (MS). John Zajicek of the University of Plymouth and his team gave 630 patients either a placebo, cannabis extract, or a synthetic form of marijuana's most active ingredient, delta-9-tetrahydrocannabinol (THC).

After 15 weeks, 60% of patients taking the drugs reported that it helped their pain and muscle stiffness, compared with 46% of those on the placebo. It also helped them to walk more easily.

Doctors' ratings of patients mobility, and their own perceptions of tremor or fatigue did not improve. This discrepancy may be because the drug alters patients' perception of discomfort, suggests Zajicek. There was little difference between the cannabis extract and THC.

The results, although mixed, hint that cannabis is as good as some existing, imperfect MS medicines, says multiple sclerosis researcher Luanne Metz of the University of Calgary in Canada. "It wasn't 'wow this is fab' stuff," she says. "But it's hard for anyone to argue that there isn't a benefit."

Based on the trial, British patient group the Multiple Sclerosis Society is calling for cannabis-based drugs to be licensed for sufferers of the disease. "[We] believe those who might benefit should be able to have treatment prescribed," said chief executive Mike O'Donovan in a statement.

Smoke stack

An estimated 2.5 million people worldwide suffer from MS, an incurable disease of the nervous system causing spasms, pain, tremor and bladder problems. An unknown proportion use cannabis, often by smoking, to ease their symptoms. Clinical trials of cannabis-based medicines have been slow in coming.

Clinical trials of cannabis-based medicines have been slow in coming. The medicinal use of cannabis is tolerated in some US states and European countries. But doctors fear that smoking will boost the risk of lung disease, and are concerned that there is no sound evidence that smoked marijuana, which contains a cocktail of chemicals, is actually beneficial.

THC, under the brand name Marinol, is licensed for treating HIV-related weight loss and nausea associated with chemotherapy, but not for use in MS. The German-made cannabis extract used in the trial, called Cannador, is not a licensed drug.

Zajicek says that it is now up to the manufacturers of Marinol and Cannador to approach drug-regulation authorities such as the US Food and Drug Administration to apply for a licence for MS prescriptions. "It also depends on political will," he adds. 

  • References

    1. Zajicek, J. et al. Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study): multicnetre randomised placebo-controlled trial. The Lancet, 362, 1517 - 1526, (2003).  | Article | ChemPort |