Cannabis-based medicines could be on the shelves of chemist shops before the end of the year, thanks to an Oxford researcher.

Dr Philip Robson with the cannabis spray

Dr Philip Robson of Oxford University's department of psychiatry has carried out clinical trials on cannabis with a view to using the drug to treat pain caused by multiple sclerosis or cancer.

He is medical director of GW Parmaceuticals, which has an office at the Magdalen Science Park, Oxford. A spokesman for the company said he hoped the new mouth-spray would be sold in UK chemists this year.

Now the company has signed a £30m deal with German pharmaceutical giant Bayer to market its first product, Sativex, as a treatment for the pain suffered by people with MS.

As a result of the deal, shares in the company rose to 232p, compared with just 81p a year ago.

The results of the drug's Phase 3 trials have now been submitted to the Medicines and Healthcare Products Regulatory Agency (MHRA).

GW grows 40,000 cannabis plants a year at a secret site in the English countryside.

A licence application was submitted to the MHRA in March. Tests are currently taking place to assess whether the drug can help cancer sufferers.

Because of its cannabis content, Sativex will also require a change in the law, but Home Secretary David Blunkett has already indicated that he would be willing to make the amendment if the drug received approval.

GW's executive chairman, Geoffrey Guy, said: "It is GW's first commercial collaboration and marks the start of a new phase in the company's history.

"As a leading global pharmaceutical company, Bayer is well placed to maximise the market opportunity for GW's product."

The deal also gives Bayer the option to negotiate marketing rights covering other European Union countries as well as a selection of other places.

GW has indicated in the past that once approval was received for the UK, it would examine the possibility of entering the market in other Commonwealth countries such as Canada, Australia and New Zealand. GW employs about 100 people across the UK. Shares in the company climbed 1 p to 233 p on the news.

Dr Robson said: "We are taking our key from history.

"Cannabis has been known to have therapeutic qualities since the dawn of civilisation and we are now analysing its ingredients."Tell us what you think.