Category Archives: Chronic Pain

Cannabinoids-induced peripheral analgesia depends on activation of BK channels.

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 Brain Research“The endogenous cannabinoid system is involved in the physiological inhibitory control of pain and is of particular interest for the development of therapeutic approaches for pain management.

Selective activation of the peripheral CB1 cannabinoid receptor has been shown to suppress the heightened firing of primary afferents, which is the peripheral mechanism underlying neuropathic pain after nerve injury. However, the mechanism underlying this effect of CB1 receptor remains unclear.

The large-conductance calcium-activated potassium (BK) channels have been reported to participate in anticonvulsant and vasorelaxant effects of cannabinoids. We asked whether BK channels participate in cannabinoids-induced analgesia and firing-suppressing effects in primary afferents after nerve injury.

Here, using mice with chronic constriction injury(CCI)-induced neuropathic pain, antinociception action and firing-suppressing effect of HU210 were measured before and after BK channel blocker application. We found that local peripheral application of HU210 alleviated CCI-induced pain behavior and suppressed the heightened firing of injured fibers. Co-administration of IBTX with HU210 significantly reversed the analgesia and the firing-suppressing effect of HU210.

This result indicated that the peripheral analgesic effects of cannabinoids depends on activation of BK channels.”

https://www.ncbi.nlm.nih.gov/pubmed/30615887

https://www.sciencedirect.com/science/article/pii/S0006899319300071?via%3Dihub

Cannabinoids and Pain: New Insights From Old Molecules.

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“Cannabis has been used for medicinal purposes for thousands of years.

The prohibition of cannabis in the middle of the 20th century has arrested cannabis research.

In recent years there is a growing debate about the use of cannabis for medical purposes.

The term ‘medical cannabis’ refers to physician-recommended use of the cannabis plant and its components, called cannabinoids, to treat disease or improve symptoms.

Chronic pain is the most commonly cited reason for using medical cannabis.

Cannabinoids act via cannabinoid receptors, but they also affect the activities of many other receptors, ion channels and enzymes.

Preclinical studies in animals using both pharmacological and genetic approaches have increased our understanding of the mechanisms of cannabinoid-induced analgesia and provided therapeutical strategies for treating pain in humans.

The mechanisms of the analgesic effect of cannabinoids include inhibition of the release of neurotransmitters and neuropeptides from presynaptic nerve endings, modulation of postsynaptic neuron excitability, activation of descending inhibitory pain pathways, and reduction of neural inflammation.

Recent meta-analyses of clinical trials that have examined the use of medical cannabis in chronic pain present a moderate amount of evidence that cannabis/cannabinoids exhibit analgesic activity, especially in neuropathic pain.

The main limitations of these studies are short treatment duration, small numbers of patients, heterogeneous patient populations, examination of different cannabinoids, different doses, the use of different efficacy endpoints, as well as modest observable effects.

Adverse effects in the short-term medical use of cannabis are generally mild to moderate, well tolerated and transient. However, there are scant data regarding the long-term safety of medical cannabis use.

Larger well-designed studies of longer duration are mandatory to determine the long-term efficacy and long-term safety of cannabis/cannabinoids and to provide definitive answers to physicians and patients regarding the risk and benefits of its use in the treatment of pain.

In conclusion, the evidence from current research supports the use of medical cannabis in the treatment of chronic pain in adults. Careful follow-up and monitoring of patients using cannabis/cannabinoids are mandatory.”

https://www.ncbi.nlm.nih.gov/pubmed/30542280

https://www.frontiersin.org/articles/10.3389/fphar.2018.01259/full

Patients’ and clinicians’ perspectives of co-use of cannabis and opioids for chronic non-cancer pain management in primary care.

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International Journal of Drug Policy

“The prevalence of opioid-associated morbidity and mortality underscores the need for research on non-opioid treatments for chronic non-cancer pain (CNCP). Pain is the most common medical condition for which patients request medical cannabis. Limited research indicates that patients are interested in cannabis as a potential addition to or replacement for opioid medication. This analysis reports on CNCP patient and clinician perceptions about the co-use of cannabis and opioids for CNCP management.

METHODS:

We interviewed 23 clinicians and 46 CNCP patients, using semi-structured interview guides, from six safety-net clinics across the San Francisco Bay Area, and 5 key stakeholders involved in CNCP management. We used a modified grounded theory approach to code and analyze transcripts.

RESULTS:

CNCP patients described potential benefits of co-use of cannabis and opioids for pain management and concerns about dosing and addictive potential. Patients reported seeking cannabis when unable to obtain prescription opioids. Clinicians stated that their patients reported cannabis being helpful in managing pain symptoms. Clinicians expressed concerns about the potential exacerbation of mental health issues resulting from cannabis use.

CONCLUSION:

Clinicians are hampered by a lack of clinically relevant information about cannabis use, efficacy and side-effects. Currently no guidelines exist for clinicians to address opioid and cannabis co-use, or to discuss the risk and benefits of cannabis for CNCP management, including side effects. Cannabis and opioid co-use was commonly reported by patients in our sample, yet rarely addressed during clinical CNCP care. Further research is needed on the risks and benefits of cannabis and opioid co-use.”

https://www.ncbi.nlm.nih.gov/pubmed/30472467

https://www.sciencedirect.com/science/article/pii/S0955395918302287

The level of evidence of medical marijuana use for treating disabilities: a scoping review.

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“There is sufficient evidence that medical marijuana is effective in treating epileptic seizures and chronic pain.

Medical marijuana may improve the level of functioning and quality of life for individuals with certain disabilities.”

https://www.ncbi.nlm.nih.gov/pubmed/30456993

https://www.tandfonline.com/doi/abs/10.1080/09638288.2018.1523952?journalCode=idre20

Association of Cannabinoid Administration With Experimental Pain in Healthy Adults: A Systematic Review and Meta-analysis.

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Image result for jama psychiatry “Cannabinoid drugs are widely used as analgesics, but experimental pain studies have produced mixed findings. The analgesic properties of cannabinoids remain unclear.

OBJECTIVE:

To conduct a systematic review and meta-analysis of the association between cannabinoid drug administration and experimental pain outcomes in studies of healthy adults.

CONCLUSIONS AND RELEVANCE:

Cannabinoid drugs may prevent the onset of pain by producing small increases in pain thresholds but may not reduce the intensity of experimental pain already being experienced; instead, cannabinoids may make experimental pain feel less unpleasant and more tolerable, suggesting an influence on affective processes. Cannabis-induced improvements in pain-related negative affect may underlie the widely held belief that cannabis relieves pain.”

https://www.ncbi.nlm.nih.gov/pubmed/30422266

https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2701671

THC and gabapentin interactions in a mouse neuropathic pain model.

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Neuropharmacology

“Clinical studies have shown that the major psychoactive ingredient of Cannabis sativa Δ9-tetrahydrocannabinol (THC) has some analgesic efficacy in neuropathic pain states.

However, THC has a significant side effect profile. We examined whether the profile of THC could be improved by co-administering it with the first-line neuropathic pain medication gabapentin.

These findings indicate that gabapentin synergistically enhances the anti-allodynic actions of THC and improves its therapeutic window.

Thus, THC may represent a potential adjuvant for neuropathic pain medications such as gabapentin.”

https://www.ncbi.nlm.nih.gov/pubmed/30312630

https://www.sciencedirect.com/science/article/pii/S0028390818307779?via%3Dihub

Cannabinoid Delivery Systems for Pain and Inflammation Treatment.

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“There is a growing body of evidence to suggest that cannabinoids are beneficial for a range of clinical conditions, including pain, inflammation, epilepsy, sleep disorders, the symptoms of multiple sclerosis, anorexia, schizophrenia and other conditions.

The transformation of cannabinoids from herbal preparations into highly regulated prescription drugs is therefore progressing rapidly. The development of such drugs requires well-controlled clinical trials to be carried out in order to objectively establish therapeutic efficacy, dose ranges and safety.

The low oral bioavailability of cannabinoids has led to feasible methods of administration, such as the transdermal route, intranasal administration and transmucosal adsorption, being proposed. The highly lipophilic nature of cannabinoids means that they are seen as suitable candidates for advanced nanosized drug delivery systems, which can be applied via a range of routes.

Nanotechnology-based drug delivery strategies have flourished in several therapeutic fields in recent years and numerous drugs have reached the market. This review explores the most recent developments, from preclinical to advanced clinical trials, in the cannabinoid delivery field, and focuses particularly on pain and inflammation treatment. Likely future directions are also considered and reported.”

https://www.ncbi.nlm.nih.gov/pubmed/30262735

https://www.mdpi.com/1420-3049/23/10/2478

Association of Cannabinoid Administration With Experimental Pain in Healthy Adults A Systematic Review and Meta-analysis

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“Patients have reliably endorsed the belief that cannabis is helpful in alleviating pain.

Cannabinoids (the collective term for all of the drugs examined in this study, including plant-based cannabis, which can contain multiple compounds) have long been considered effective for reducing pain and are frequently proposed as treatment options in pain management.

Cannabinoid drugs may prevent the onset of pain by producing small increases in pain thresholds but may not reduce the intensity of experimental pain already being experienced; instead, cannabinoids may make experimental pain feel less unpleasant and more tolerable, suggesting an influence on affective processes.

Cannabis-induced improvements in pain-related negative affect may underlie the widely held belief that cannabis relieves pain.”

 https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2701671

“Cannabinoid drugs make pain feel ‘less unpleasant, more tolerable'”  https://www.sciencedaily.com/releases/2018/09/180919111454.htm

“Medical marijuana increases pain threshold for patients”  https://www.upi.com/Health_News/2018/09/19/Medical-marijuana-increases-pain-threshold-for-patients/1771537292969/?rc_fifo=1

“Study reveals cannabinoid drugs make pain feel ‘less unpleasant, more tolerable'”  https://medicalxpress.com/news/2018-09-reveals-cannabinoid-drugs-pain-unpleasant.html

“Cannabinoid drugs reduce perceived unpleasantness of painful stimuli and increase tolerance” https://www.news-medical.net/news/20180919/Cannabinoid-drugs-reduce-perceived-unpleasantness-of-painful-stimuli-and-increase-tolerance.aspx

“Cannabinoids appear to increase pain tolerability”  https://www.healio.com/psychiatry/practice-management/news/online/%7B7626bb3f-ce35-4968-99bc-50ecdaac79b7%7D/cannabinoids-appear-to-increase-pain-tolerability

Effect of cannabidiolic acid and ∆9-tetrahydrocannabinol on carrageenan-induced hyperalgesia and edema in a rodent model of inflammatory pain.

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“Cannabidiol (CBD), a non-intoxicating component of cannabis, or the psychoactive Δ9-tetrahydrocannabiol (THC), shows anti-hyperalgesia and anti-inflammatory properties.

OBJECTIVES:

The present study evaluates the anti-inflammatory and anti-hyperalgesia effects of CBD’s potent acidic precursor, cannabidiolic acid (CBDA), in a rodent model of carrageenan-induced acute inflammation in the rat hind paw, when administered systemically (intraperitoneal, i.p.) or orally before and/or after carrageenan. In addition, we assess the effects of oral administration of THC or CBDA, their mechanism of action, and the efficacy of combined ineffective doses of THC and CBDA in this model. Finally, we compare the efficacy of CBD and CBDA.

RESULTS:

CBDA given i.p. 60 min prior to carrageenan (but not 60 min after carrageenan) produced dose-dependent anti-hyperalgesia and anti-inflammatory effects. In addition, THC or CBDA given by oral gavage 60 min prior to carrageenan produced anti-hyperalgesia effects, and THC reduced inflammation. The anti-hyperalgesia effects of THC were blocked by SR141716 (a cannabinoid 1 receptor antagonist), while CBDA’s effects were blocked by AMG9810 (a transient receptor potential cation channel subfamily V member 1 antagonist). In comparison to CBDA, an equivalent low dose of CBD did not reduce hyperalgesia, suggesting that CBDA is more potent than CBD for this indication. Interestingly, when ineffective doses of CBDA or THC alone were combined, this combination produced an anti-hyperalgesia effect and reduced inflammation.

CONCLUSION:

CBDA or THC alone, as well as very low doses of combined CBDA and THC, has anti-inflammatory and anti-hyperalgesia effects in this animal model of acute inflammation.”

https://www.ncbi.nlm.nih.gov/pubmed/30225659

https://link.springer.com/article/10.1007%2Fs00213-018-5034-1

Cannabidiol enhances morphine antinociception, diminishes NMDA-mediated seizures and reduces stroke damage via the sigma 1 receptor.

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“Cannabidiol (CBD), the major non-psychotomimetic compound present in the Cannabis sativa plant, exhibits therapeutic potential for various human diseases, including chronic neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, ischemic stroke, epilepsy and other convulsive syndromes, neuropsychiatric disorders, neuropathic allodynia and certain types of cancer.

CBD does not bind directly to endocannabinoid receptors 1 and 2, and despite research efforts, its specific targets remain to be fully identified. Notably, sigma 1 receptor (σ1R) antagonists inhibit glutamate N-methyl-D-aspartate acid receptor (NMDAR) activity and display positive effects on most of the aforesaid diseases. Thus, we investigated the effects of CBD on three animal models in which NMDAR overactivity plays a critical role: opioid analgesia attenuation, NMDA-induced convulsive syndrome and ischemic stroke.

In an in vitro assay, CBD disrupted the regulatory association of σ1R with the NR1 subunit of NMDAR, an effect shared by σ1R antagonists, such as BD1063 and progesterone, and prevented by σ1R agonists, such as 4-IBP, PPCC and PRE084. The in vivo administration of CBD or BD1063 enhanced morphine-evoked supraspinal antinociception, alleviated NMDA-induced convulsive syndrome, and reduced the infarct size caused by permanent unilateral middle cerebral artery occlusion.

These positive effects of CBD were reduced by the σ1R agonists PRE084 and PPCC, and absent in σ1R-/- mice. Thus, CBD displays antagonist-like activity toward σ1R to reduce the negative effects of NMDAR overactivity in the abovementioned experimental situations.”

https://www.ncbi.nlm.nih.gov/pubmed/30223868

https://molecularbrain.biomedcentral.com/articles/10.1186/s13041-018-0395-2