Cannabis for the Treatment of Chronic Pain in the Era of an Opioid Epidemic: A Symposium-Based Review of Sociomedical Science.

Pain Medicine

“This manuscript reviews medical literature published pertaining to the management of chronic pain with medical marijuana therapy (MMJ), with an emphasis on the social, medical, and legal aspects of therapy.

CONCLUSIONS:

Increasing interest in MMJ for chronic pain underscores a need for primary care and pain physicians to better understand the indications and evidence for its use free from cultural bias. Given a lack of full conclusive clinical utility, continued research is needed to better understand how to best utilize MMJ therapy for the treatment of chronic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/29016917

https://academic.oup.com/painmedicine/article-abstract/doi/10.1093/pm/pnx143/3964518/Cannabis-for-the-Treatment-of-Chronic-Pain-in-the?redirectedFrom=fulltext

Cannabis and Cannabinoids for Chronic Pain.

Current Rheumatology Reports

“The purpose of this study was to provide the most up-to-date scientific evidence of the potential analgesic effects, or lack thereof, of the marijuana plant (cannabis) or cannabinoids, and of safety or tolerability of their long-term use.

RECENT FINDINGS:

We found that inhaled (smoked or vaporized) cannabis is consistently effective in reducing chronic non-cancer pain.

Oral cannabinoids seem to improve some aspects of chronic pain (sleep and general quality of life), or cancer chronic pain, but they do not seem effective in acute postoperative pain, abdominal chronic pain, or rheumatoid pain.

The available literature shows that inhaled cannabis seems to be more tolerable and predictable than oral cannabinoids. Cannabis or cannabinoids are not universally effective for pain. Continued research on cannabis constituents and improving bioavailability for oral cannabinoids is needed. Other aspects of pain management in patients using cannabis require further open discussion: concomitant opioid use, medical vs. recreational cannabis, abuse potential, etc.”

Is cannabis an effective treatment for joint pain?

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“Cannabis has been used to treat pain for thousands of years.

However, since the early part of the 20th century, laws restricting cannabis use have limited its evaluation using modern scientific criteria. Over the last decade, the situation has started to change because of the increased availability of cannabis in the United States for either medical or recreational purposes, making it important to provide the public with accurate information as to the effectiveness of the drug for joint pain among other indications.

The major psychotropic component of cannabis is Δ9-tetrahydrocannabinol (THC), one of some 120 naturally occurring phytocannabinoids. Cannabidiol (CBD) is another molecule found in herbal cannabis in large amounts. Although CBD does not produce psychotropic effects, it has been shown to produce a variety of pharmacological effects. Hence, the overall effects of herbal cannabis represent the collective activity of THC, CBD and a number of minor components.

The action of THC is mediated by two major G-protein coupled receptors, cannabinoid receptor type 1 (CB1) and CB2, and recent work has suggested that other targets may also exist. Arachidonic acid derived endocannabinoids are the normal physiological activators of the two cannabinoid receptors.

Natural phytocannabinoids and synthetic derivatives have produced clear activity in a variety of models of joint pain in animals. These effects are the result of both inhibition of pain pathway signalling (mostly CB1) and anti-inflammatory effects (mostly CB2). There are also numerous anecdotal reports of the effectiveness of smoking cannabis for joint pain.

Indeed, it is the largest medical request for the use of the drug. However, these reports generally do not extend to regulated clinical trials for rheumatic diseases. Nevertheless, the preclinical and human data that do exist indicate that the use of cannabis should be taken seriously as a potential treatment of joint pain.”

https://www.ncbi.nlm.nih.gov/pubmed/28967368

Do Medical Marijuana Laws Reduce Addictions and Deaths Related to Pain Killers?

NATIONAL BUREAU OF ECONOMIC RESEARCH

“Many medical marijuana patients report using marijuana to alleviate chronic pain from musculoskeletal problems and other sources. If marijuana is used as a substitute for powerful and addictive pain relievers in medical marijuana states, a potential overlooked positive impact of medical marijuana laws may be a reduction in harms associated with opioid pain relievers, a far more addictive and potentially deadly substance. To assess this issue, we study the impact of medical marijuana laws on problematic opioid use. We use two measures of problematic use: treatment admissions for opioid pain reliever addiction from the Treatment Episode Data Set (TEDS) and state-level opioid overdose deaths in the National Vital Statistics System (NVSS). Using both standard differences-in-differences models as well as synthetic control models, we find that states permitting medical marijuana dispensaries experience a relative decrease in both opioid addictions and opioid overdose deaths compared to states that do not. We find no impact of medical marijuana laws more broadly; the mitigating effect of medical marijuana laws is specific to states that permit dispensaries. We evaluate potential mechanisms. Our findings suggest that providing broader access to medical marijuana may have the potential benefit of reducing abuse of highly addictive painkillers.”

http://www.nber.org/papers/w21345.pdf

“Cannabis use is associated with a substantial reduction in premature deaths in the United States. These data suggest that Cannabis use may decrease premature deaths. Overall, prohibition is estimated to lead to similar numbers of premature deaths as drunk driving, homicide, or fatal opioid overdose. Cannabis use prevents thousands of premature deaths each year, and Cannabis prohibition is revealed as a major cause of premature death in the U.S.” https://scholarworks.iu.edu/dspace/handle/2022/21632

Preferences for Medical Marijuana over Prescription Medications Among Persons Living with Chronic Conditions: Alternative, Complementary, and Tapering Uses.

Mary Ann Liebert, Inc. publishers

“Despite expanded legalization and utilization of medical cannabis (MC) internationally, there is a lack of patient-centered data on how MC is used by persons living with chronic conditions in tandem with or instead of prescription medications. This study describes approaches to use of MC vis-à-vis prescription medications in the treatment of selected chronic conditions.

RESULTS:

Participants described a range of approaches to using MC, including (1) as alternatives to using prescription or over-the-counter medications; (2) complementary use with prescription medications; and (3) as a means for tapering off prescription medications. Motives reported for reducing or eliminating prescription medications included concerns regarding toxicity, dependence, and tolerance, and perceptions that MC improves management of certain symptoms and has quicker action and longer lasting effects.

CONCLUSIONS:

MC appears to serve as both a complementary method for symptom management and treatment of medication side-effects associated with certain chronic conditions, and as an alternative method for treatment of pain, seizures, and inflammation in this population. Additional patient-centered research is needed to identify specific dosing patterns of MC products associated with symptom alleviation and produce longitudinal data assessing chronic disease outcomes with MC use.”

Efficacy of Cannabis-Based Medicines for Pain Management: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

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“The management of chronic pain is a complex challenge worldwide. Cannabis-based medicines (CBMs) have proven to be efficient in reducing chronic pain, although the topic remains highly controversial in this field.

OBJECTIVES:

This study’s aim is to conduct a conclusive review and meta-analysis, which incorporates all randomized controlled trials (RCTs) in order to update clinicians’ and researchers’ knowledge regarding the efficacy and adverse events (AEs) of CBMs for chronic and postoperative pain treatment.

CONCLUSIONS:

The current systematic review suggests that CBMs might be effective for chronic pain treatment, based on limited evidence, primarily for neuropathic pain (NP) patients. Additionally, GI AEs occurred more frequently when CBMs were administered via oral/oromucosal routes than by inhalation.”

https://www.ncbi.nlm.nih.gov/pubmed/28934780

Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis.

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“Osteoarthritis (OA) is a multifactorial joint disease, which includes joint degeneration, intermittent inflammation, and peripheral neuropathy. Cannabidiol (CBD) is a non-euphoria producing constituent of cannabis that has the potential to relieve pain.

The aim of this study was to determine if CBD is anti-nociceptive in OA, and whether inhibition of inflammation by CBD could prevent the development of OA pain and joint neuropathy.

The therapeutic and prophylactic effects of peripheral CBD (100-300μg) were assessed. In end stage OA, CBD dose-dependently decreased joint afferent firing rate, and increased withdrawal threshold and weight bearing (p<0.0001; n=8). Acute, transient joint inflammation was reduced by local CBD treatment (p<0.0001; n=6). Prophylactic administration of CBD prevented the development of MIA-induced joint pain at later time points (p<0.0001; n=8), and was also found to be neuroprotective (p<0.05; n=6-8).

The data presented here indicate that local administration of CBD blocked OA pain. Prophylactic CBD treatment prevented the later development of pain and nerve damage in these OA joints.

These findings suggest that CBD may be a safe, useful therapeutic for treating OA joint neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/28885454             https://insights.ovid.com/crossref?an=00006396-900000000-99152

The Endogenous Cannabinoid System: A Budding Source of Targets for Treating Inflammatory and Neuropathic Pain.

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“A great need exists for the development of new medications to treat pain resulting from various disease states and types of injury. Given that the endogenous cannabinoid (ie, endocannabinoid) system modulates neuronal and immune cell function, both of which play key roles in pain, therapeutics targeting this system hold promise as novel analgesics.

Potential therapeutic targets include the cannabinoid receptors, type 1 and 2, as well as biosynthetic and catabolic enzymes of the endocannabinoids N-arachidonoylethanolamine and 2-arachidonoylglycerol. Notably, cannabinoid receptor agonists as well as inhibitors of endocannabinoid-regulating enzymes fatty acid amide hydrolase and monoacylglycerol lipase produce reliable antinociceptive effects, and offer opioid-sparing antinociceptive effects in myriad preclinical inflammatory and neuropathic pain models.

Emerging clinical studies show that ‘medicinal’ cannabis or cannabinoid-based medications relieve pain in human diseases, such as cancer, multiple sclerosis, and fibromyalgia.

Here, we examine the preclinical and clinical evidence of various endocannabinoid system targets as potential therapeutic strategies for inflammatory and neuropathic pain conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/28857069

https://www.nature.com/npp/journal/vaop/naam/abs/npp2017204a.html

Endocannabinoids Have Opposing Effects On Behavioral Responses To Nociceptive And Non-nociceptive Stimuli.

“The endocannabinoid system is thought to modulate nociceptive signaling making it a potential therapeutic target for treating pain.

However, there is evidence that endocannabinoids have both pro- and anti-nociceptive effects. In previous studies using Hirudo verbana (the medicinal leech), endocannabinoids were found to depress nociceptive synapses, but enhance non-nociceptive synapses. Here we examined whether endocannabinoids have similar bidirectional effects on behavioral responses to nociceptive vs. non-nociceptive stimuli in vivo.

These results provide evidence that endocannabinoids can have opposing effects on nociceptive vs. non-nociceptive pathways and suggest that cannabinoid-based therapies may be more appropriate for treating pain disorders in which hyperalgesia and not allodynia is the primary symptom.”

Delta-9-tetrahydrocannabinol decreases masticatory muscle sensitization in female rats through peripheral cannabinoid receptor activation.

European Journal of Pain

“This study investigated whether intramuscular injection of delta-9-tetrahydrocannabinol (THC), by acting on peripheral cannabinoid (CB) receptors, could decrease nerve growth factor (NGF)-induced sensitization in female rat masseter muscle; a model which mimics the symptoms of myofascial temporomandibular disorders.

It was found that CB1 and CB2 receptors are expressed by trigeminal ganglion neurons that innervate the masseter muscle and also on their peripheral endings.

These results suggest that reduced inhibitory input from the peripheral cannabinoid system may contribute to NGF-induced local myofascial sensitization of mechanoreceptors. Peripheral application of THC may counter this effect by activating the CB1 receptors on masseter muscle mechanoreceptors to provide analgesic relief without central side effects.

SIGNIFICANCE:

Our results suggest THC could reduce masticatory muscle pain through activating peripheral CB1 receptors. Peripheral application of cannabinoids could be a novel approach to provide analgesic relief without central side effects.”

https://www.ncbi.nlm.nih.gov/pubmed/28722246

http://onlinelibrary.wiley.com/doi/10.1002/ejp.1085/abstract