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Cannabis drugs pass testing 'milestone'

13:42 05 November 02

NewScientist.com news service

Cannabis-based drugs could be prescribed in the UK as early as 2003, following successful final-stage trials in patients with multiple sclerosis.

Compared with standard treatments alone, the drugs significantly improved symptoms of MS and reduced pain caused by other types of nerve damage, GW Pharmaceuticals has announced. The company is the sole UK holder of a licence to cultivate and supply cannabis for medical research.

"These results represent a milestone in the pharmaceutical development of cannabis-based medicines," says Geoffrey Guy, GW's executive chairman. "Subject to regulatory approval, we are now on track to deliver our first prescription medicine to the UK market next year."

Existing legislation would have to be altered to permit doctors to prescribe cannabis-based medicines. But the UK government has said it would make these legal changes if large-scale trials showed the medicines offered a "clear benefit".

Other research groups around the world are testing cannabis-based drugs. But the GW results are from the most advanced large-scale trials.

Psychoactive effects

On Tuesday, GW announced the results of four randomised, double-blind Phase III trials. Phase III trials are normally the final round before the creators of a new drug seek regulatory approval.

The GW trials investigated the effectiveness of a "whole plant medicinal cannabis extract", containing active ingredients tetrahydrocannabinol (THC) and cannabidiol (CBD) as its principal components. The drug was delivered as a spray into the mouth.

Throughout the trials, patients receiving either the treatment or a placebo continued to take their regular prescribed medications.

The trials on about 350 patients showed significant reductions in spasticity and pain and improvements in sleep in people with MS. Patients with another type of nerve damage also reported a reduction in pain. No serious psychoactive effects were reported.

Illegal use

The UK's Multiple Sclerosis Society said the results are "very encouraging". An estimated 10 per cent of the UK's MS sufferers use cannabis illegally to help combat symptoms. GW has another five cannabis trials in progress. These are investigating other uses of the drug, for treating pain in cancer and spinal cord injury, for example. The results of these trials are due in 2003.

However, the results of previous trials in Europe have suggested that cannabis-based drugs are no better than existing treatments for cancer pain and have more serious side effects.

In May 2001, the US Supreme Court ruled that cannabis could not be legally used as medicine. If cannabis-based drugs are given the all-clear in the UK, analysts expect that the rest of Europe and Canada will be next to grant approval, within about six to nine months. But the US might not follow for at least two years, due to stricter tests required by its Food and Drug Administration.

Emma Young

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