Cannabidiol ineffective for low back pain

Cannabidiol provides no benefit for people with acute low back pain, an Australian RCT has found.

Researchers in Victoria investigated the drug based on its approval in other countries for use neuropathic pain and because unlike cannabinoids that contain tetrahydrocannabinol (THC), cannabidiol does not have psychomotor or cognitive effects.

The study of cannabidiol conducted at the Austin Hospital in Melbourne randomised 100 patients in the ED to standard treatment plus a single 400mg oral dose of cannabidiol (CBD) or standard treatment plus placebo.

Standard treatment included 100 mg paracetamol and 400 mg ibuprofen, with oxycodone available if pain was not adequately managed.

The study, published in The MJA, found mean pain scores at two hours were similar for the CBD and placebo groups (6.2 v 5.8 points on a 0-10 numerical rating scale).

As well, the median length of emergency department stay was similar in both groups (9.0 v 8.5 hours).

The total oxycodone use, from four hours preceding CBD or placebo to four hours after their administration, was also similar in both groups (230 v 215 mg).

Side effects, mostly sedation, were also similar in both groups of patients.

The investigators said their findings support other evidence, including from systematic reviews, that cannabinoids were not effective as analgesics for acute pain or chronic non-cancer pain.

They also said their findings were important given people were increasingly looking for non-opioid pain control and especially given the high cost of CBD.

“With the gradual legalisation of medicinal and recreational cannabis use in Australia and other countries, physicians must expect to see increasing numbers of patients taking cannabis products, whether prescribed by physicians or not.”

“It is imperative that the medical utility of CBD and other cannabis products, their side effects, and how these products interact with other medications be investigated in well designed studies.”

Despite some enthusiastic and vocal consumer advocates for medicinal cannabis products, there is little other evidence-based support for their use outside cancer and neuropathic pain.

Recent recommendations from the Australian and New Zealand College of Anaesthetists (ANZCA) Faculty of Pain Medicine said there was “a critical lack of evidence” that medicinal cannabis provides a consistent benefit for any type of chronic non-cancer pain.

“In addition, evidence of harms does exist, particularly in relation to sedative effects, interactions with other medications and neuropsychiatric effects (for products which contain tetrahydrocannabinol (THC).”

“Do not prescribe currently available medicinal cannabis products to treat chronic non-cancer pain (CNCP) unless part of a registered clinical trial,” they said in recent Choosing Wisely recommendations.

Also this year, the International Association for the Study of Pain (IASP) has said it does not endorse the general use of cannabinoids to treat pain.

Pain medicine physician Associate Professor Michael Vagg, from Deakin University, wrote recently in The Conversation that the IASP statement would be controversial.

“In the polite and understated world of academic medicine, this is about as big a smackdown as it gets.”

Associate Professor Vagg, an ANZCA councillor, said that the only party likely to benefit from CBD use was the manufacturer.

“If medicinal cannabis was truly as potentially valuable as often claimed, we would be the loudest voice in favour of wider access. The weight of evidence points us away from this conclusion.”

The ARA’s 2016 statement says: “There is currently not enough supportive evidence to recommend medical cannabis as a clinical intervention for chronic musculoskeletal pain outside of a clinical trial setting.”

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