Medical Cannabis – An Evidenced-Based, Harm Reduction Approach to Prescription Opiate Use


National Access Cannabis, in collaboration with PhytoSciences Consulting, a U.S. company specializing in clinical trial design pertaining to medical cannabis, will be establishing the first two-year pharmacovigilance project to monitor outcomes and adverse events related to the use of cannabis for medical purposes in Canada. This project will provide important observational data to support future evidenced-based clinical trials.


Canada and the U.S. are at the center of an opioid overdose epidemic. Canada ranks second only to the U.S. in per capita consumption of prescription opioids, which are primarily used to treat acute and chronic pain1. Deaths due to opiate overdose continue to rise across Canada, forcing federal and provincial authorities to respond to this growing epidemic. Across Canada, far too many people are dying from drug overdoses. Overdose deaths due to medical and non-medical drug use are now the third leading cause of accidental death in Ontario2. A significant proportion of these deaths have been attributed to opioids. In recent news, it was indicated that in Ontario alone, these drugs have killed nearly 2,500 people between 2011 and 20143.

According to recent figures released from the British Columbia Coroners Service, from January to April of this year alone, fentanyl, a powerful synthetic opioid primarily prescribed for chronic pain, was detected in 56 % of all deaths from overdoses compared to 5 % in 20124. The International Narcotics Control Board reports that Canadians’ use of prescription opioids increased by 203% between 2000 and 2010, an increase steeper than in the U.S.5

In Canada and the U.S., cannabis is cultivated, manufactured, and distributed for medicinal purposes. However, few studies have thus far described its therapeutic efficacy or subjective (adverse) effects in patients. Clinical trials need to be completed to assess the therapeutic satisfaction within a group of patients using prescribed pharmaceutical-grade cannabis and to compare the subjective effects among the available formulations as compared to prescription opiate use.

Fundamentally, physicians need an alternative to treating chronic pain. One option that has emerged in the research literature which has received minimal attention is another contentious political issue–medical cannabis. There is increasing evidence that cannabis can potentially be an effective treatment for chronic pain, presenting a safe and viable alternative or adjunct to pharmaceutical opiates.

There is a growing body of evidence to support the use of medical cannabis as an adjunct to or substitute for prescription opiates in the treatment of chronic pain. When used in conjunction with opiates, cannabinoids lead to a greater cumulative relief of pain, resulting in a reduction in the use of opiates (and associated side-effects) by patients in a clinical setting. Additionally, cannabinoids can prevent the development of tolerance to and withdrawal from opiates, and can even rekindle opiate analgesia after a prior dosage has become ineffective.

However, there is limited clinical trial evidence available, including information about adverse effects, different formulations and dosages. This evidence would provide a basis to create clinical guidelines for healthcare practitioners. From a medical perspective, the key information gaps are in the clinical evidence healthcare practitioners need to advise patients on optimal dosages, formulations and routes of administration with respect to comorbidities as well as on contraindications, adverse effects, and drug-drug interactions or medical conditions.


In Canada, cannabis is cultivated and distributed for medicinal purposes as commissioned by Health Canada. However, few studies have thus far described its therapeutic efficacy or subjective (adverse) effects in patients. The aims of this study are to assess the therapeutic satisfaction within a group of patients using prescribed pharmaceutical-grade cannabis and to compare the subjective effects among the available formulations as compared to prescription opiate use.

This will be the first study to conduct a two-year, multi-site, evidenced-based cohort study investigating the potential of cannabis as a substitute or adjunctive treatment for opiates in the treatment of chronic pain. This landmark study will present information, options and next steps for developing effective, evidence-based policy for the potential substitution of opiates with cannabis.

One aspect of this groundbreaking study is that we will, for the first time, implement multi-site cohort study designs to recruit a subset of participants naive to cannabis and measure their pain levels over a specified time period. The results of this study may aid in further research and critical appraisal for medicinally prescribed cannabis versus opiates in addition to supporting future clinical trials.

Design, Outcomes, and Measure

An online, PHIA compliant Patient Questionnaire (categorical multiple-choice with or without free text items pertaining to the use of pharmaceutical cannabinoid formulations) will be utilized to gather data for this study. Data to be collected will include demographic information, alterations in opioid use, type of firmulation and dosage information, route of administration, frequency of use, change in body weight, quality of life, medication classes used, medication side effects before and after initiation of cannabis administration, adverse effects, frequency of cannabis use, change in opioid prescription drug use, side effects in combination with cannabis, number of medications used before and after cannabis use, type of pain indication (acute or chronic), etiology (neuropathic, degenerative, oncologic, autoimmune / Connective Tissue Disorder – SLE, RA), inciting event (traumatic or atraumatic), and previous therapies (medications, surgery, physical therapy, chiropractic, injections).

Subjective effects will be measured with psychometric scales and used to compare among the formulations / formulations of cannabis used across this group of patients in comparison to using prescribed opiates.

1International Narcotics Control Board. (2013). Narcotics Drugs: Estimated World Requirements for 2013; Statistics for 2011. New York: United Nations.




5 International Narcotics Control Board. (2011). Narcotics Drugs: Estimated World Requirements for 2012; Statistics for 2010. New York: United Nations