Substituting Medical Cannabis for Other Drugs, Alcohol a Common Practice

Michael Vlessides

February 14, 2019

Substituting medical cannabis for other drugs such as opioids and alcohol is a common practice, new research shows.

A survey of more than 2000 cannabis users showed that 69.1% of these individuals substituted cannabis for prescription drugs, particularly opioids. Other common substitutions included alcohol (44.5%), tobacco (31.1%), and illicit substances (26.6%).

These findings, the investigators note, suggest that increased regulated access to cannabis may reduce the use of other potentially harmful agents.

"From a public health point of view, we feel our most interesting finding is the high rate of substitution for prescription drugs, alcohol, tobacco, and illicit substances," said Philippe Lucas, VP of Global Patient Research and Access at Tilray, Inc, and a Graduate Researcher with the Canadian Institute of Substance Use Research.

"Most significantly, this is the first examination of cannabis substitution patterns that's offered a detailed perspective on such substitutions," Lucas told Medscape Medical News. "So we've not only asked if people were substituting for prescription drugs, but also asked them what they're substituting for as well as the rate of substitution."

The study was published in the January 28 issue of Harm Reduction Journal.

Questions and Answers

Previous research supports the therapeutic use of cannabis in the treatment of chronic pain and related conditions. Nevertheless, there is a growing body of evidence suggesting cannabis use may play a role in the consumption of other substances, both legal and illegal, including alcohol, tobacco, cocaine, heroin, and other opioids.

A 2014 study showed a mean annual opioid overdose mortality rate that was 24.8% lower in states with medical cannabis laws than in those without such laws. In 2018, investigators concluded that medical cannabis laws were associated with opioid prescribing rates almost 6% lower than in states that did not allow medical cannabis.

Given these early findings, the investigators sought to gain more insight into how and why people use medical cannabis, as well as the effects of its consumption on the use of other, potentially more harmful, agents.

With that in mind, they designed a 239-question patient-feedback questionnaire to gather comprehensive information on patient demographics, access to cannabis, cannabis-use patterns, and cannabis substitution effects from Canadian patients registered with a federally authorized medical cannabis production company.  

The survey included a series of multiple choice, ranking, and open-ended questions regarding a variety of factors, including frequency of use, methods of ingestion, and preferred cannabis variety. Survey participants were also asked questions regarding their use of prescription drugs, alcohol, tobacco, and illicit substances.

Individuals who responded positively were then asked if they had ever used cannabis as a substitute for these agents. Those who noted substitutions for either prescription drugs or illicit drugs then named as many as three drugs that were substituted, as well as the frequency with which cannabis was substituted for each drug.

In total, 2032 individuals completed the survey (mean age 40 years). The most common primary condition reported by the respondents was chronic pain (29.4%; n = 598), followed by mental-health conditions (27%; n = 548). In total, pain and mental health conditions accounted for 83.7% of all primary conditions.

Almost three quarters of all respondents (74.6%; n = 1515) reported daily cannabis consumption; median use was twice daily. The mean daily amount used was 1.5 grams.

No Magic Elixir

The most commonly cited substitution was for prescription drugs (69.1%; n = 953), followed by alcohol (44.5%; n = 515), tobacco (31.1%; n = 406), and illicit substances (26.6%; n = 136). Interestingly, women were more likely than men to report substitutions (P < .01).

Respondents named a total of 1730 specific prescription drugs for which they substituted cannabis, including opioids (35.3%), anti-depressants (21.5%); non-opioid pain medications (10.9%), anti-seizure medications (8.6%), muscle relaxants/sleep aids (8.1%), and benzodiazepines (4.3%).

Among a total of 610 mentions, participants reported they stopped using opioids completely in 59.3% of instances; another 18.4% reported reducing opioid use by at least 75%.

Among 515 respondents who substituted cannabis for alcohol, 30.9% said they stopped using alcohol completely, while another 36.7% reported reducing alcohol consumption by at least 75%.

A total of 406 individuals substituted cannabis for tobacco. Of these, 50.7% reported completely stopping tobacco use, while 13.8% reported reducing tobacco use by 75%.

Among those who substituted cannabis for illicit substances, cocaine/crack was the most frequently substituted drug (17.4%; n = 89). Others included psychedelics (11.7%; n = 60), nonprescription opioids (5.7%; n = 29), stimulants (2.7%; n = 14), and depressants (1.6%; n = 8). Among respondents who cited substituting cannabis for illicit substances, 72.2% suggested they substituted 100% for the drug in question.

Although the researchers were quick to acknowledge that cannabis — which comes with its own set of side effects — is by no means a magic elixir for the opioid crisis, the survey suggests regulating access to cannabis for certain patients may provide an opportunity to "maximize the potential positive impacts on public health and safety stemming from cannabis substitution effect," the researchers write.

Current Approach Ad Hoc

Commenting for Medscape Medical News, June H. Kim, MPhil, MHS, Department of Epidemiology, Columbia University, New York City, said the study's findings are consistent with those from several similar surveys.

"The findings regarding potential substitution are of most interest, to me, particularly in regards to treating conditions related to pain and mental health," said Kim, who was not involved in the study.

"The significance of these findings would be more apparent if they could be linked to actual prescription data," Kim added. "In the US, states with medical cannabis laws have been shown to have declines in Medicare/Medicaid prescribing. While I can't speak to the Canadian healthcare system, this has significant implications regarding healthcare costs in the US."

In the near future, physicians may begin to promote cannabis as a substitute for other substances.

"These results suggest that we need to get more engaged with this. Most of these substitutions seem to be happening in an ad hoc manner. But in some cases, such as with opioid reduction, it could be very favorable if it's done in a systematic way, Kim said.

Lucas disclosed that he is an employee of Tilray, the company that sponsored the study. Kim has disclosed no relevant financial relationships.

Harm Reduct J.  Published online January 28, 2019. Abstract

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