US interest in MS drug boosts GW

US investors piled into GW Pharmaceuticals yesterday amid excitement over the prospects for an American launch of its revolutionary cannabis-based treatment for multiple sclerosis.

Health regulators have sent an uncompromising message that smoked cannabis will not be approved for use by MS sufferers, leaving the way open for GW's under-the-tongue spray version of the drug.

Justin Gover, the managing director, said GW'sshares had attracted attention from private investors.

GW shares are listed in London, where they closed up 10 per cent at 98p.

The interest has been sparked by a Food & Drug Administration ruling last week that "no sound scientific studies supported medical use of marijuana for treatment in the US, and no animal or human data supported the safety or efficacy of marijuana for general medical use". The agency is trying to re-establish control after 11 states allowed doctors to suggest the use of smoked cannabis.

In January, the FDA gave GW permission to start trials of its spray, Sativex, in the US this year. The drug is sold in Canada and could make it to the US market by the end of the decade.

Mr Gover said: "The FDA's announcement shows that one can, on the one hand, not support smoking cannabis as a medicine and, on the other, support the concept of a cannabis-derived medicine that meets normal standards of safety and efficacy as a welcome solution to the problem."

Scientists disagree over the effectiveness of cannabis as a treatment for the symptoms of MS.