The Japan Times - Cannabis extract relieves chronic back pain: high-quality trial

Lower back pain is the leading cause of disability worldwide, affecting more than half a billion people, according to the World Health Organization.

But drugs for chronic back pain are limited to common painkillers such as ibuprofen, which can have serious side effects when used long-term, or highly addictive and potentially dangerous opioids.

In recent years, an expanding cannabis industry has claimed that a range of marijuana or cannabidiol (CBD) products can help with pain, but researchers have warned that the quality of evidence actually showing this has been low.

On Wednesday, a large placebo-controlled, phase 3 clinical trial -- which is considered the gold standard for researching medical drugs -- testing a cannabis extract was published in the journal Nature Medicine.

The trial involved more than 800 people with chronic lower back pain who did not get relief from non-opioid drugs.

After 12 weeks of taking either the cannabis extract called VER-01 or a placebo, participants were asked to report their pain level on a 10-point scale.

Those taking the extract reported a 1.9-point reduction in pain, compared to 0.6 for those on the placebo.

After six months, participants taking the extract said their pain had decreased by a higher 2.9 points.

They also reported better sleep, physical function and quality of life, according to the study.

Each dose of VER-01 contains 2.5  milligrammes of THC, the main active ingredient in marijuana.

Nothing suggested that the extract was addictive or caused serious side effects, the study said. The most common side effects were short-term dizziness, sleepiness, dry mouth and some nausea -- though they decreased over time.

The study's lead author Matthias Karst, a professor of pain medicine at Hannover Medical School in Germany, told AFP that "no feelings of (being) high" were observed during the trial.

- 'As good as it gets' -

Andrew Moore, a former pain researcher at Oxford University not involved in the study, said the "terrific" trial was "about as good as it gets".

"The trial is the first that shows good quality evidence that something in the cannabis plant can be helpful for pain," he told AFP.

But Moore also urged caution about claims that the extract was not addictive, warning that in the past, such statements have later turned out to be incorrect.

Most cannabis products vary widely in potency, purity and other factors which make them difficult for doctors to safely prescribe, Karst said.

The VER-01 strain has been specifically developed to obtain approval by medical authorities and then be prescribed for chronic pain, he added.

This means the study is not "proof that all cannabis/CBD products would be helpful in the same way," Karst emphasised.

Jan Vollert, a pain researcher at Exeter University not involved in the study, also stressed the difference between this "very specific substance" and regular marijuana.

"Smoking cannabis and taking VER-01 are probably as similar as eating hazelnuts and eating Nutella: they might share a similar basis, but they just are not comparable," he said.

S.Fujimoto--JT