Cannabinoid replacement drug trial to help cannabis smokers quit habit

An Australian research team is recruiting cannabis smokers who need help quitting or reducing their cannabis-use for a world-first trial of cannabinoid replacement therapy for relapse prevention in the community.

This pioneering study builds on this team’s previous work demonstrating that the drug suppressed cannabis withdrawal symptoms in an inpatient setting.

“If the trial of Sativex® proves effective it could be a promising breakthrough in the treatment of cannabis dependence that affects one in ten users,” says the study’s chief investigator Professor Nick Lintzeris of the University of Sydney.

“Cannabis dependence can contribute to an array of health problems, including cognitive, psychiatric, cardiovascular and respiratory disorders. Given a worldwide cannabis-using population of 180 million people, an effective therapy could reduce a lot of the harm associated with dependent-use of the drug.”

Existing treatments for cannabis dependence have had only modest success. Current best-practice counselling approaches, such as cognitive behavioural therapy, reveal that 70 to 80% of patients relapse within six months. Treatments for acute cannabis withdrawal have similar relapse rates.

“More effective approaches are clearly needed for the tens of thousands of Australians seeking help each year for cannabis-related problems,” Nick Lintzeris notes. “As with treatment of many other addictions, we are keen to examine the effects of combining counselling with medication, as this has proven to often be more effective than either approach alone.”

The treatment model in the Sativex trial is similar to the use of nicotine replacement medication to help people stop tobacco use, or methadone to help people stop heroin use.

The research team is seeking 140 cannabis-dependent users aged 18 to 65 years to participate in a 14-week randomised control trial of Sativex. Half the participants will receive Sativex while the other half will receive a placebo. Both groups will receive structured best practice counselling, regular case management and medical reviews over the course of the trial. Participants will be followed up 12 weeks after the medication phase to assess the trial’s longer term impact.

Sativex study trial participant, Michael, had smoked cannabis for 20 years and despite trying to quit many times, had never succeeded: “I had tried hypnotherapy and going cold turkey but I wasn’t able to stop, even though I wanted to,” says the 44-year-old web developer from Sydney.

“I wanted to quit to get more focused and take charge of my career. I was also troubled by ongoing side effects like chronic bronchitis, trouble getting to sleep, intense dreams and irrational thoughts.”

Since participating in the Sativex trial, Michael has quit cannabis and feels happy that he has kicked a long term habit: “I stopped using cannabis in March and haven’t smoked it since. I felt no withdrawal physical symptoms and had no cravings at all.”

Sativex is a substitute for cannabis that delivers cannabinoids at sufficient levels to reduce withdrawal and cravings in heavy cannabis users, and hopefully prevent relapse to illicit cannabis use. It is a liquid medication delivered as a spray into the mouth and so avoids the harms associated with smoking cannabis.

Sativex contains extracts from cannabis sativa plants grown under controlled conditions. These extracts contain tetrahydrocannabinol (THC) and cannabidiol (CBD), with small amounts of other plant-derived cannabinoids. CBD has no intoxicating effects and recent research indicates that it has powerful anxiolytic, antidepressant and antipsychotic properties, potentially countering some of the harmful effects of THC.

Professor Lintzeris says: “The rationale for replacement medications, such as Sativex, in cannabis dependence is they may provide a safer route of administration than smoking, they should reduce illicit cannabis use by preventing withdrawal and reducing cravings that often lead to relapse, and enable greater engagement in counselling services.

“Together, these effects should empower patients to make the necessary lifestyle changes and distance themselves from regular cannabis use, prior to tapering off the medication.”

The trial is operating from four sites across NSW:  The Langton Centre in Surry Hills, St George Hospital, Kogarah and sites in Western Sydney and Newcastle.

If you would like to know more about participating in the Sativex trial, contact Dr Anjali Bhardwaj on (02) 9332 8794 or email anjali.bhardwaj@sydney.edu.au

(Source: The University of Sydney)