Category Archives: Chronic Pain

Cannabinoid effects on responses to quantitative sensory testing among individuals with and without clinical pain: a systematic review.

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Image result for wolters kluwer“There has been an explosion of interest in the utility of cannabinoids as potential analgesics.

This systematic review critically synthesizes the evidence for cannabinoid analgesic effects on quantitative sensory testing outcomes in both healthy adults and patients with chronic non-cancer pain (CNCP).

Our systematic review protocol is pre-registered on PROSPERO (CRD42018117367). An electronic search was made in PsycINFO, Cochrane, Google Scholar, Embase, and Pubmed of all literature published until August 2018. Of the 1,217 studies found from the search, a total 39 placebo-controlled studies that met the eligibility criteria were synthesized for the present study. Due to substantial heterogeneity of study designs, populations, cannabinoid compounds, and quantitative sensory testing outcomes, meta-analysis was not conducted.

More consistent evidence of cannabinoid analgesia was observed for inhaled cannabis than synthetic cannabinoids.

Analgesic effects were most commonly observed in tests of cold pain sensitivity, and hyperalgesic effects were most commonly observed in tests of electrical stimulation. Patterns of findings from studies with healthy subjects did not substantively differ from those with CNCP. However, these observations are qualified by the high degree of inconsistency across studies and methodological heterogeneity. We offer recommendations for future studies to improve study rigor and reproducibility.”

 https://www.ncbi.nlm.nih.gov/pubmed/31613869
https://insights.ovid.com/crossref?an=00006396-900000000-98577

Cellular Distribution of Canonical and Putative Cannabinoid Receptors in Canine Cervical Dorsal Root Ganglia.

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Image result for frontiers in veterinary science“Growing evidence indicates cannabinoid receptors as potential therapeutic targets for chronic pain.

Consequently, there is an increasing interest in developing cannabinoid receptor agonists for treating human and veterinary pain.

The present study may represent a morphological substrate to consider in order to develop therapeutic strategies against chronic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/31608295

“The anti-nociceptive potential of the endocannabinoid system has prompted the development of therapeutic cannabinoid receptors agonists or medical marjiuana to be used in pets in order to treat chronic pain.”

https://www.frontiersin.org/articles/10.3389/fvets.2019.00313/full

Cannabinoid Receptor Type 1 and Its Role as an Analgesic: An Opioid Alternative?

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 Publication Cover“Understanding how the body regulates pain is fundamental to develop rational strategies to combat the growing prevalence of chronic pain states, opioid dependency, and the increased financial burden to the medical care system.

Pain is the most prominent reason why Americans seek medical attention and extensive literature has identified the importance of the endocannabinoid pathway in controlling pain. Modulation of the endocannabinoid system offers new therapeutic opportunities for the selective control of excessive neuronal activity in several pain conditions (acute, inflammatory, chronic, and neuropathic).

Cannabinoids have a long history of medicinal use and their analgesic properties are well documented; however, there are major impediments to understanding cannabinoid pain modulation.

One major issue is the presence of psychotropic side effects associated with D9-tetrahydrocannabinol (THC) or synthetic derivatives, which puts an emphatic brake on their use. This dose-limiting effect prevents the appropriate degree of analgesia .

Animal studies have shown that the psychotropic effects are mediated via brain cannabinoid type 1 (CB1) receptors, while analgesic activity in chronic pain states may be mediated via CB1R action in the spinal cord, brainstem, peripheral sensory neurons, or immune cells.

The development of appropriate therapies is incumbent on our understanding of the role of peripheral versus central endocannabinoid-driven analgesia. Recent physiological, pharmacological, and anatomical studies provide evidence that one of the main roles of the endocannabinoid system is the regulation of gamma-aminobutyric acid (GABA) and/or glutamate release.

This article will review this evidence in the context of its implications for pain. We first provide a brief overview of CB1R’s role in the regulation of nociception, followed by a review of the evidence that the peripheral endocannabinoid system modulates nociception.

We then look in detail at regulation of central-mediated analgesia, followed up with evidence that cannabinoid mediated modulation of pain involves modulation of GABAergic and glutamatergic neurotransmission in key brain regions. Finally, we discuss cannabinoid action on non-neuronal cells in the context of inflammation and direct modulation of neurons.

This work stands to reveal long-standing controversies in the cannabinoid analgesia area that have had an impact on failed clinical trials and implementation of therapeutics targeting this system.”

https://www.ncbi.nlm.nih.gov/pubmed/31596190

https://www.tandfonline.com/doi/abs/10.1080/15504263.2019.1668100?journalCode=wjdd20

The effect of cannabis laws on opioid use.

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International Journal of Drug Policy“Many Americans rely on opioids at varying dosages to help ameliorate their suffering. However, empirical evidence is mounting that opioids are ineffective at controlling non-cancer related chronic pain, and many argue the strategies meant to relieve patient suffering are contributing to the growing opioid epidemic.

Concurrently, several states now allow the use of medical cannabis to treat a variety of medical conditions, including chronic pain. Needing more exploration is the impact of cannabis laws on general opioid reliance and whether chronic pain sufferers are opting to use cannabis medicinally instead of opioids.

METHODS:

This study investigates the effect of Medical Marijuana Laws (MML)s on opioid use and misuse controlling for a number of relevant factors using data from several years of the National Survey on Drug Use and Health and multivariate logistic regression and longitudinal analysis strategies.

RESULTS:

Results provide evidence that MMLs may be effective at reducing opioid reliance as survey respondents living in states with medical cannabis legislation are much less apt to report using opioid analgesics than people living in states without such laws, net other factors. Results further indicate that the presence of medicinal cannabis legislation appears to have no influence over opioid misuse.

CONCLUSION:

MMLs may ultimately serve to attenuate the consequences of opioid overreliance.”

https://www.ncbi.nlm.nih.gov/pubmed/31590091

https://www.sciencedirect.com/science/article/abs/pii/S0955395919302567?via%3Dihub

Role of Cannabinoids and Terpenes in Cannabis-Mediated Analgesia in Rats.

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View details for Cannabis and Cannabinoid Research cover image

“Cannabis sativa has been used for centuries in treating pain. However, the analgesic role of many of its constituents including terpenes is unknown. This research examined the contributions of terpenes (volatile oil) and cannabinoids in cannabis-mediated analgesia in rats.

Methods: Animals received intraperitoneal administration of either vehicle, 10.0 or 18.0 mg/kg morphine, or various doses of the extract without terpenes, isolated terpenes, Δ9-tetrahydrocannabinol (THC), or the full extract. Thirty minutes later animals were tested on hotplate and tail-flick tests of thermal nociception. One week later, rats received a second administration of test articles and were tested 30 min later in the abdominal writhing test of inflammatory nociception.

Results: In the thermal assays, hotplate and tail-flick latencies for morphine-treated rats were dose dependent and significantly higher than vehicle-treated animals. All the cannabinoid compounds except for the isolated terpenes produced dose-dependent increases in hotplate and tail-flick latencies. In the inflammatory nociceptive assay, animals treated with vehicle and isolated terpenes demonstrated increased abdominal writhing, whereas all the cannabinoid compounds significantly decreased abdominal writhing responses.

Conclusions: Overall, THC alone produced robust analgesia equivalent to the full cannabis extract, whereas terpenes alone did not produce analgesia. These data suggest the analgesic activity of cannabis is largely mediated by THC, whereas terpenes alone do not cause alterations in cannabis-mediated analgesia.”

https://www.ncbi.nlm.nih.gov/pubmed/31579834

“The work herein demonstrates that cannabis extracts can not only produce robust analgesia without the terpene-containing volatile oils, but isolated THC appears to be all that is required to produce such effects.”

https://www.liebertpub.com/doi/10.1089/can.2018.0054

Cannabinoids, Pain, and Opioid Use Reduction: The Importance of Distilling and Disseminating Existing Data.

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View details for Cannabis and Cannabinoid Research cover image“The high prevalence of chronic pain conditions combined with an over-reliance on opioid prescriptions has resulted in an opioid epidemic and a desperate need for solutions.

There is some debate about whether cannabis might play a role in addressing chronic pain conditions as well as the opioid epidemic.

Recent surveys suggest that a large number of people are using cannabis as a treatment for pain and to reduce use of opioids, and cannabis-derived products demonstrate at least modest efficacy in the treatment of pain in randomized controlled trials.

In addition, surveillance studies from countries that have approved the use of Sativex, which is a cannabis-based product, have demonstrated that a combination of Δ9-tetrahydrocannabinol and cannabidiol has low potential for harm, is well tolerated, and is helpful to patients.

Given the number of people in the United States who are already using cannabis to manage pain and opioid use in state-regulated markets, it is imperative to conduct additional research in these areas, and to disseminate information on how to minimize harm and maximize any benefits of using cannabinoids to mitigate pain and reduce opioid use.

The purpose of this article is to call attention to the fact that cannabis is being used in the management of chronic pain. Thus, this article also provides a set of guidelines on how to approach using cannabis to treat pain.”

https://www.ncbi.nlm.nih.gov/pubmed/31579833

https://www.liebertpub.com/doi/10.1089/can.2018.0052

Endogenous cannabinoid modulation of restraint stress-induced analgesia in thermal nociception.

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Journal of Neurochemistry banner“It is thought that endogenous cannabinoids have a role in the analgesia induced by specific forms of stress.

We examined if the role of endogenous cannabinoids is also dependent upon the mode of nociception, and whether this could be altered by drugs which block their enzymatic degradation.

These findings indicate the role of endocannabinoids in stress-induced analgesia differs with the type of thermal pain behaviour. However, by inhibiting their breakdown, endocannabinoids can be recruited to substitute for endogenous opioid signalling when their activity is blocked, indicating a degree of redundancy between opioid and cannabinoid systems.

Together these data suggest targeting endocannabinoid breakdown could provide an alternative, or adjuvant to mainstream analgesics such as opioids.”

https://www.ncbi.nlm.nih.gov/pubmed/31571215

https://onlinelibrary.wiley.com/doi/abs/10.1111/jnc.14884

Involvement of Spinal Cannabinoid CB2 Receptors in Exercise-Induced Antinociception.

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Neuroscience“Muscle pain affects approximately 11-24% of the global population.

Several studies have shown that exercise is a non-pharmacological therapy to pain control. It has been suggested that the endocannabinoid system is involved in this antinociceptive effect.

The present study aimed to investigate whether spinal cannabinoid CB2 receptors participate in the exercise-induced antinociception.

The present study suggests that activation of spinal cannabinoid CB2 receptors and reduction of activated microglia are involved in exercise-induced antinociception.”

https://www.ncbi.nlm.nih.gov/pubmed/31473278

https://www.sciencedirect.com/science/article/abs/pii/S0306452219306165?via%3Dihub

“Exercise activates the endocannabinoid system.”  https://www.ncbi.nlm.nih.gov/pubmed/14625449

“The endocannabinoid system and pain.”  https://www.ncbi.nlm.nih.gov/pubmed/19839937

Comparative studies of endocannabinoid modulation of pain.

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Philosophical Transactions of the Royal Society B: Biological Sciences cover image

“Cannabinoid-based therapies have long been used to treat pain, but there remain questions about their actual mechanisms and efficacy. From an evolutionary perspective, the cannabinoid system would appear to be highly conserved given that the most prevalent endogenous cannabinoid (endocannabinoid) transmitters, 2-arachidonyl glycerol and anandamide, have been found throughout the animal kingdom, at least in the species that have been analysed to date. This review will first examine recent findings regarding the potential conservation across invertebrates and chordates of the enzymes responsible for endocannabinoid synthesis and degradation and the receptors that these transmitters act on. Next, comparisons of how endocannabinoids modulate nociception will be examined for commonalities between vertebrates and invertebrates, with a focus on the medicinal leech Hirudo verbana. Evidence is presented that there are distinct, evolutionarily conserved anti-nociceptive and pro-nociceptive effects. The combined studies across various animal phyla demonstrate the utility of using comparative approaches to understand conserved mechanisms for modulating nociception. This article is part of the Theo Murphy meeting issue ‘Evolution of mechanisms and behaviour important for pain’.”

https://www.ncbi.nlm.nih.gov/pubmed/31544609

https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0279

Medical cannabis for chronic pain: can it make a difference in pain management?

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 “Globally, chronic pain is a major therapeutic challenge and affects more than 15% of the population. As patients with painful terminal diseases may face unbearable pain, there is a need for more potent analgesics.

Although opioid-based therapeutic agents received attention to manage severe pain, their adverse drug effects and mortality rate associated with opioids overdose are the major concerns.

Evidences from clinical trials showed therapeutic benefits of cannabis, especially delta-9-tetrahydrocannabinol and cannabinoids reduced neuropathic pain intensity in various conditions. Also, there are reports on using combination cannabinoid therapies for chronic pain management.

The association of cannabis dependence and addiction has been discussed much and the reports mentioned that it can be comparatively lower than other substances such as nicotine and alcohol.

More countries have decided to legalise the medicinal use of cannabis and marijuana.

Healthcare professionals should keep themselves updated with the changing state of medical cannabis and its applications.”

https://www.ncbi.nlm.nih.gov/pubmed/31535218

https://link.springer.com/article/10.1007%2Fs00540-019-02680-y