A ground-breaking cannabis-based drug for treating symptoms of multiple sclerosis has been approved in Britain, in a landmark decision for its creator GW Pharmaceuticals.

The Aim-listed biotech company has been developing Sativex, which uses compounds extracted from marijuana plants, for more than a decade and has finally been granted a licence from the UK regulator.

Clinical trials have shown that Sativex, which is sprayed under the tongue, reduces spasticity in multiple sclerosis patients who do not respond adequately to existing therapies.

t became the world's first cannabis medicine to win regulatory clearance when it was approved in Canada in 2005 for neuropathic pain, but its roll-out in Britain – and other European markets thereafter – is a larger sales opportunity.

Last month, GW Pharmaceuticals indicated that the medicine would be approved by the end of June, with the final stages of the approval process involving only finalising product's packaging.

At the time, Dr Geoffrey Guy, chairman of GW, said: "The first six months of this year have proven the most important in GW's history, in which we have made material progress towards Sativex's launch in Europe and generated positive cancer pain data."

Although the market was anticipating approval in late June, Friday's news sent shares up 11pc to a four-year high of 143p in early afternoon trading. By the bell, shares were up 12 – or 9.3pc – to 141p.

A regulatory green light in Spain is expected shortly after the British approval.

Sativex is to be marketed in Britain by Germany's Bayer and in the rest of Europe by Spain's Almirall.

Analysts at Piper Jaffray have previously said that UK regulatory approval would trigger the first commercial sales and a £10m milestone payment from Bayer.

The broker anticipates that sales of Sativex in multiple sclerosis spasticity could reach £121m in Europe and Canada alone.

Labels: Medical Marijuana, sativex