CANNABIS could be offered to surgical patients at York Hospital as part of a study to assess the pain-relieving properties of the drug.

The hospital is one of 36 across the UK to sign up for the Medical Research Council (MRC) study to find out if oral cannabis plant extract could provide effective pain relief after an operation.

The trial is looking to recruit 400 surgical patients from participating hospitals.

There is already some anecdotal evidence that suggests cannabis could be effective at relieving pain for a variety of debilitating conditions such as multiple sclerosis.

According to the MRC, administering drugs to alleviate post-operative pain is a routine procedure in hospitals and this provides a useful way to measure the effects of cannabis against other pain- relieving drugs.

Patients will be randomly assigned to one of four oral treatments containing either standardised cannabis extract, tetrahydrocannabinol (an active ingredient in cannabis), a standard pain-relieving drug, or a placebo.

Pain relief and side effects will be assessed over a six-hour period. Patients will be asked by a researcher to respond to questions about their pain and general feelings, such as sickness, every half to one hour while they are awake. Patients can request additional pain relief at any time.

After six hours of study, volunteers may receive a choice of standard pain medications, either another oral drug or an alternative form of pain medication.

The £500,000 MRC-funded trial is being led by Dr Anita Holdcroft from Imperial College London, at the Chelsea and Westminster Hospital.

Dr Holdcroft said that no patient would be left without access to pain relief during the trial.

She said: "Many patients and clinicians want an answer to the question of whether cannabis is effective at relieving pain.

"We need to assess the scientific merits of some of the anecdotal evidence and we need to do this in the same way as any other experimental pain treatment."

Updated: 10:46 Wednesday, August 20, 2003