Using provincial health administrative databases, researchers found that while synthetic oral cannabinoid use was relatively low among adults over the age of 66 with COPD (0.6 per cent), this group was twice as likely to be using these drugs compared to adults of the same age without COPD (0.3 per cent).

The research led by St. Michael's Hospital in Toronto and the not-for-profit research institute ICES raises concerns about the use of synthetic cannabinoids, human-made versions of tetrahydrocannabinol (THC) -- a key chemical in marijuana. When ingested, THC activates receptors in the central nervous system, producing a variety of potential effects including sedation, anxiety, muscle weakness and pain relief.

COPD is a progressive lung disease that causes breathing difficulty, but it can be associated with a variety of other problems too, like chronic muscle pain and insomnia. Psychoactive drug classes, like cannabinoids, are often prescribed to help reduce pain, promote sleep and decrease difficult-to-control breathlessness.

"Our study showed that patients and clinicians are turning to cannabinoids more frequently to manage the symptoms associated with COPD, but little is known about the potential dangers associated with this medication class," said Dr. Nicholas Vozoris, lead author, a respirologist at St. Michael's and an associate scientist at the hospital's Li Ka Shing Knowledge Institute and ICES.

"Previous studies by our team found that other psychoactive drugs, like opioids and benzodiazepines, are frequently used in COPD. We wanted to find out if this was the case too for synthetic oral cannabinoids."

Researchers also found that synthetic oral cannabinoids were used more frequently in subgroups of older adults with COPD at heightened risk for adverse events, such as those with psychiatric disease and those receiving other sedating psychoactive medications.

"Safety recommendations provided for these medications advise against prescribing cannabinoids in these groups," said Dr. Vozoris. "And yet these individuals with COPD are being exposed at greater rates."

The team also found that synthetic oral cannabinoids were used more often in potentially concerning ways among older adults with COPD, including more frequently at higher doses and for longer durations of time.

"Though the use of these drugs isn't too frequent today, without careful monitoring of the way they're being prescribed and used now, we could end up with larger problems in the future," Dr. Vozoris said.

As one of the first studies to describe the use of this drug class in individuals with COPD, Dr. Vozoris said these results provide a basis for future research to examine the effects of oral synthetic cannabinoid use on respiratory outcomes among individuals with COPD.

The results also provide a foundation for clinicians to make more informed decisions regarding the use of this drug class.

"We hope that clinicians read our paper and walk away with a better understanding of this drug class," said Dr. Vozoris. "We'd like them to reflect on their own prescribing practices and ensure cannabinoid drugs are used and prescribed with vigilance."