The widespread prescribing of opioids for the management of acute and chronic pain over the last decades made opioids readily available to the general public, creating a public health crisis.1,2 As of 2017, it was estimated that more than 36 million people worldwide have opioid use disorder.3,4 The majority of  opioid users report acquiring these agents from relatives and/or friends, despite knowing the risk of addiction.1.2

While the risk factors for and treatment of opioid addiction are well established, treating patients with acute and chronic pain remains a challenge. However, withdrawing opioids as a means of hazard reduction for addiction in a patient with chronic pain can have an adverse effects on the patient’s well-being. This is not limited to medication withdrawal illness and recurrence of pain, but may also threaten the patient’s perceived quality of life, compromising recovery.5

Because of the controversy surrounding opioid prescribing and use, there has been rising interest in alternative pain treatment regimens that could be clinically advantageous in reducing opioid use and complications associated with pain. One example is the use of medical cannabis. Though used since antiquity, only recently has public sentiment and state laws on medicinal cannabis use shifted to a more favorable frame. With 33 of the 50 states (and the District of Columbia) fully legalizing medical cannabis use, alternatives in treatment pathways that have classically been restrictive can now be entertained.5-10

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In 2017, it was estimated that 56% of patients who suffer from chronic pain use cannabis.5,7 It is therefore incumbent on the medical community to consider the practicality and appropriateness of prescription use for cannabis, especially with rising public climate of approval and openness for dialogue.

Mechanisms for Pain Management

Opioids have long been the mainstay of treatment in the management of moderate to severe pain associated with several disease states afflicting patients in both the acute and chronic care setting, despite limited evidence supporting their continued use.11 The mechanism of action opioids has been binding to specific opioid receptor protein, that when occupied, limit the expression of pain perception on the part of the patient.11 Yet, this protein is also involved with perception and expression of mood and stress, and can affect the immune system.11 This is accomplished at the expense of receptor-derived dependence and side effects, most notably those of central nervous system (CNS) and respiratory depression.11

This differs markedly from what is understood about the role of cannabis in pain modulation. Cannabis is believed to act on the endocannabinoid system; particularly receptors 1 (CB1) and 2 (CB2).12 These receptors enhances the sensitivity of the CNS neurotransmitters to serotonin and dopamine, thereby providing stimulation of pain relief.8,12  In so doing, this pathway also plays a role in euphoria and perception of decreased levels of stress, which is more pronounced from CB1.12

Effectiveness of Cannabis for Chronic Pain

The pharmacokinetic properties of cannabis are dependent on the purity of the agent, route of administration, physiology of the user, as well as the condition being treated.8,12 Cannabis has been most effective at treating chronic pain associated with non-specific neuropathy (including muscle spasticity), cancer pain, and rheumatoid arthritis.5,10,12  

Though synthetic derivatives are of interest as a product of abuse, the most commonly explored medical agents are non-synthetic.12 One exception has been the US Food and Drug approval of dronabinol (tetrahydrocannabinal [THC]) for the treatment of nausea and vomiting associated with cancer chemotherapy and AIDS-associated anorexia. Dronabinol has also been shown to reduce chronic pain, but most commonly success was met only when the agent was combined with opioids.12 At this time the evidence of adequate pain relief with synthetic cannabis as monotherapy is lacking and should therefore be discouraged.10

Medical cannabis can also be used as a way to reduce opioid use. A study in 2015, which included over 200 patients on a chronic opioid regimen, reported a reduction in opioid use by nearly 77% when cannabis was added to existing monontherapy.13 Similar findings were suggested in a Canadian study, where 300 patients provided a subjective assessment of pain reduction when cannabis was dispensed and added to their existing opioid regimen. A 71% reduction in prescription, illicit drug, and alcohol abuse was found for those who were receiving the medical cannabis.14 The patients also reported an additional untargeted reduction in nicotine dependency.14 The subjects also reported improved compliance with therapy and a preference to cannabis, believing that cannabis was “safer” than their existing treatment regimens, improved symptomatic relief, and was “more tolerated.”14