A paper about the University of Sydney and NSW Health clinical trial provides the first strong evidence that so-called cannabinoid agonist medication— which targets receptors in the brain—could reduce the rate of relapse. The paper published today in the American Medical Association's JAMA Internal Medicine.

An Australian study has demonstrated that cannabis-based medication helps tackle dependency on cannabis, one of the most widely used drugs globally.

Lead author, conjoint professor Nick Lintzeris, of the University of Sydney's Faculty of Medicine and Health and director of drug & alcohol services, South East Sydney Local Health District, said the study should give hope to people with dependency on cannabis, which is a leading cause of drug treatment episodes in Australia.

"We've never had the evidence before that medication can be effective in treating cannabis dependency—this is the first big study to show this is a safe and effective approach," Lintzeris said.

"The principles are very similar to nicotine replacement; you are providing patients with a medicine which is safer than the drug they're already using, and linking this with medical and counseling support to help people address their illicit cannabis use."

The cannabis concentrate, which comprises equal proportions of cannabidiol (CBD) and the psychoactive tetrahydrocannabinol (THC), is sprayed under the tongue and avoids the health impacts associated with smoking cannabis, such as respiratory issues.

Nabiximols has been primarily used to treat pain symptoms associated with multiple sclerosis and is licensed in Australia. Alternative medical cannabis products exist, but these are only available through special access schemes and unlike the trial medication, also require Therapeutic Goods Administration (TGA) approval.

This large, 12-week outpatient clinical trial of 128 participants taking nabiximols medication followed an earlier study by the same research team that had previously shown nabiximols reduces withdrawal symptoms in a short-term, hospital-treatment program. "The latest study published today is even more important in that it shows that nabiximols can be effective in helping patients achieve longer-term changes in their cannabis use," Lintzeris explains.

Co-author of the paper, professor Iain McGregor, the academic director of the University's Lambert Initiative for Cannabinoid Therapeutics, noted, "Worldwide, we are seeing medicinal cannabis patients transition away from the traditional smoked route of cannabis administration; this new study... complements this trend by showing that an oral spray can be an effective substitute for smoked cannabis in heavy recreational users seeking treatment for their cannabis use."

Lintzeris said an important element of this National Health and Medical Research Council-supported trial was that only cannabis users were recruited who had previously unsuccessfully tried to curb their use. "Our study is an important step in addressing the lack of effective treatments—currently, four in five patients relapse to regular use within 6 months of medical or psychological interventions."

Trial and medication snapshot:

• During the clinical trial, participants had an average dose of about 18 sprays a day, with each spray of 0.1 mL comprising 2.7 mg of THC and 2.5 mg of CBD
• Participants treated with nabiximols used significantly less illicit cannabis than patients randomly allocated to placebo medication
• The medicine was combined with cognitive behavioral therapy (CBT) and other therapeutic support for a holistic approach
• Health and behavioral benefits of cannabis replacement include that patients are taken out of their usual patterns of use.
• This first large, outpatient, randomized, controlled trial of the cannabis extract medication noted suppression of withdrawal and cravings, with improvements in physical and psychological well-being