THC and gabapentin interactions in a mouse neuropathic pain model.

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

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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.”

“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

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Cannabis analgesia in chronic neuropathic pain is associated with altered brain connectivity.

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“To characterize the functional brain changes involved in δ-9-tetrahydrocannabinol (THC) modulation of chronic neuropathic pain.

RESULTS:

THC significantly reduced patients’ pain compared to placebo. THC-induced analgesia was correlated with a reduction in functional connectivity between the anterior cingulate cortex (ACC) and the sensorimotor cortex. Moreover, the degree of reduction was predictive of the response to THC. Graph theory analyses of local measures demonstrated reduction in network connectivity in areas involved in pain processing, and specifically in the dorsolateral prefrontal cortex (DLPFC), which were correlated with individual pain reduction.

CONCLUSION:

These results suggest that the ACC and DLPFC, 2 major cognitive-emotional modulation areas, and their connections to somatosensory areas, are functionally involved in the analgesic effect of THC in chronic pain. This effect may therefore be mediated through induction of functional disconnection between regulatory high-order affective regions and the sensorimotor cortex. Moreover, baseline functional connectivity between these brain areas may serve as a predictor for the extent of pain relief induced by THC.”

https://www.ncbi.nlm.nih.gov/pubmed/30185448

http://n.neurology.org/content/early/2018/09/05/WNL.0000000000006293

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Cannabidiol modulates serotonergic transmission and prevents allodynia and anxiety-like behavior in a model of neuropathic pain.

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“Clinical studies indicate that cannabidiol (CBD), the primary non-addictive component of cannabis that interacts with the serotonin (5-HT) 1A receptor, may possess analgesic and anxiolytic effects. However, its effects on 5-HT neuronal activity, as well as its impact in models of neuropathic pain are unknown.

Seven days of treatment with CBD reduced mechanical allodynia, decreased anxiety-like behavior, and normalized 5-HT activity. Anti-allodynic effects of CBD were fully prevented by capsazepine (10 mg/kg/day, s.c., for 7 days) and partially prevented by WAY 100635 (2 mg/kg/day, s.c., for 7 days), while the anxiolytic effect was blocked only by WAY.

Overall, repeated treatment with low-dose CBD induces analgesia predominantly via TRPV1 activation, reduces anxiety via 5-HT1A receptor activation, and rescues impaired 5-HT neurotransmission under neuropathic pain conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/30157131

https://insights.ovid.com/crossref?an=00006396-900000000-98870

“Cannabis pain relief without the ‘high’. Canadian researchers pinpoint the mechanism of cannabidiol for safe pain relief without side effects”  https://eurekalert.org/pub_releases/2018-10/muhc-cpr102418.php

“Effective dose of cannabidiol for safe pain relief without the typical ‘high'”  https://www.news-medical.net/news/20181025/Effective-dose-of-cannabidiol-for-safe-pain-relief-without-the-typical-high.aspx

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Targeting the Endocannabinoid System for Prevention or Treatment of Chemotherapy-Induced Neuropathic Pain: Studies in Animal Models.

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“There is a scarcity of drugs to either prevent or properly manage chemotherapy-induced neuropathic pain (CINP). Cannabis or cannabinoids have been reported to improve pain measures in patients with neuropathic pain.

For this review, a search was done in PubMed for papers that examined the expression of and/or evaluated the use of cannabinoids or drugs that prevent or treat established CINP in a CB receptor-dependent manner in animal models.

Studies suggest there is a specific deficiency of endocannabinoids in the periphery during CINP.

Inhibitors of FAAH and MGL, enzymes that degrade the endocannabinoids, CB receptor agonists, desipramine, and coadministered indomethacin plus minocycline were found to either prevent the development and/or attenuate established CINP in a CB receptor-dependent manner.

The studies analysed suggest that targeting the endocannabinoid system for prevention and treatment of CINP is a plausible therapeutic option. Almost 90% of the studies on animal models of CINP analysed utilised male rodents. Taking into consideration clinical and experimental findings that show gender differences in the mechanisms involved in pain including CINP and in response to analgesics, it is imperative that future studies on CINP utilise more female models.”

“Cannabis or cannabinoids have been reported to improve pain measures in patients with neuropathic or cancer pain. The studies analysed suggest that targeting the endocannabinoid system for prevention and treatment of CINP is a plausible therapeutic option.” https://www.hindawi.com/journals/prm/2018/5234943/
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Personal experience and attitudes of pain medicine specialists in Israel regarding the medical use of cannabis for chronic pain.

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“The scientific study of the role of cannabis in pain medicine still lags far behind the growing use driven by public approval. Accumulated clinical experience is therefore an important source of knowledge. However, no study to date has targeted physicians who actually use cannabis in their daily practice.

RESULTS:

Sixty-four percent of all practicing pain specialists in Israel responded. Almost all prescribe cannabis. Among them, 63% find cannabis moderately to highly effective, 56% have encountered mild or no side effects, and only 5% perceive it as significantly harmful. Common indications are neuropathic pain (65%), oncological pain (50%), arthralgias (25%), and any intractable pain (29%). Leading contraindications are schizophrenia (76%), pregnancy/breastfeeding (65%), and age <18 years (59%). Only 12% rated cannabis as more hazardous than opiates. On a personal note, 45% prefer cannabis for themselves or a family member. Lastly, 54% would like to see cannabis legalized in Israel.

CONCLUSION:

In this survey, pain clinicians experienced in prescribing cannabis over prolonged periods view it as an effective and relatively safe treatment for chronic pain, based on their own experience. Their responses suggest a possible change of paradigm from using cannabis as the last resort.”

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Synthetic peripherally-restricted cannabinoid suppresses chemotherapy-induced peripheral neuropathy pain symptoms by CB1 receptor activation.

 Neuropharmacology

“Chemotherapy-induced peripheral neuropathy (CIPN) is a severe and dose-limiting side effect of cancer treatment that affects millions of cancer survivors throughout the world and current treatment options are extremely limited by their side effects.

Cannabinoids are highly effective in suppressing pain symptoms of chemotherapy-induced and other peripheral neuropathies but their widespread use is limited by central nervous system (CNS)-mediated side effects.

Here, we tested one compound from a series of recently developed synthetic peripherally restricted cannabinoids (PRCBs) in a rat model of cisplatin-induced peripheral neuropathy.

Our results demonstrate that PRCBs exemplified by PrNMI may represent a viable option for the treatment of CIPN pain symptoms.”

https://www.ncbi.nlm.nih.gov/pubmed/29981335

https://www.sciencedirect.com/science/article/pii/S0028390818303575?via%3Dihub

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Evidence for the use of “medical marijuana” in psychiatric and neurologic disorders.

College of Psychiatric and Neurologic Pharmacists

“Cannabis is listed as a Schedule I substance under the Controlled Substances Act of 1970, meaning the US federal government defines it as an illegal drug that has high potential for abuse and no established medical use; however, half of the states in the nation have enacted “medical marijuana” (MM) laws. Clinicians must be aware of the evidence for and against the use of MM in their patients who may consider using this substance.

RESULTS:

Publications were identified that included patients with dementia, multiple sclerosis, Parkinson disease, Huntington disease, schizophrenia, social anxiety disorder, depression, tobacco use disorder, and neuropathic pain.

DISCUSSION:

There is great variety concerning which medical conditions are approved for treatment with MM for either palliative or therapeutic benefit, depending on the state law. It is important to keep an evidence-based approach in mind, even with substances considered to be illegal under US federal law. Clinicians must weigh risks and benefits of the use of MM in their patients and should ensure that patients have tried other treatment modalities with higher levels of evidence for use when available and appropriate.”

https://www.ncbi.nlm.nih.gov/pubmed/29955495

““Medical marijuana” encompasses everything from whole-plant cannabis to synthetic cannabinoids available for commercial use approved by regulatory agencies. In determining whether MM is of clinical utility to our patients, it is important to keep in mind chemical constituents, dose, delivery, and indication. Selection of the patient appropriate for MM must be carefully considered because clinical guidelines and treatment options with stronger levels of evidence should be exhausted first in most cases. There seems to be strongest evidence for the use of MM in patients with MS and in patients with neuropathic pain; moderate evidence exists to support further research in social anxiety disorder, schizophrenia, PD, and tobacco use disorder; evidence is limited for use in patients with dementia, Huntington disease, depression, and anorexia.”

http://mhc.cpnp.org/doi/10.9740/mhc.2017.01.029?code=cpnp-site

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An overview of the cannabinoid type 2 receptor system and its therapeutic potential.

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“This narrative review summarizes recent insights into the role of the cannabinoid type 2 (CB2) receptor as potential therapeutic target in neuropathic pain and neurodegenerative conditions.

RECENT FINDINGS:

The cannabinoid system continues to receive attention as a therapeutic target. The CB2 receptor is primarily expressed on glial cells only when there is active inflammation and appears to be devoid of undesired psychotropic effects or addiction liability. The CB2 receptor has been shown to have potential as a therapeutic target in models of diseases with limited or no currently approved therapies, such as neuropathic pain and neurodegenerative conditions such as Alzheimer’s disease.

SUMMARY:

The functional involvement of CB2 receptor in neuropathic pain and other neuroinflammatory diseases highlights the potential therapeutic role of drugs acting at the CB2 receptor.”

https://www.ncbi.nlm.nih.gov/pubmed/29794855

https://insights.ovid.com/crossref?an=00001503-900000000-98981

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Cannabinoid WIN-55,212-2 mesylate inhibits tumor necrosis factor-α-induced expression of nitric oxide synthase in dorsal root ganglion neurons.

 

“Tumor necrosis factor-α (TNF-α) is an established pain modulator in the peripheral nervous system. Elevated levels of TNF-α in dorsal root ganglion (DRG) neurons reportedly is critical for neuropathic pain processing. It has been shown that the production of nitric oxide, a key player in the development and maintenance of nociception, depends on the expression of nitric oxide synthases (NOSs) and their activities.

Accumulating evidence also supports an important role of cannabinoids in modulating neuropathic pain.

In this study, we explored the effects and the underlying mechanisms of crosstalk between TNF-α and cannabinoid on the expression/activity of NOS in DRG neurons.

Our findings suggest that TNF-α induces the expression/activity of nNOS in DRG neurons by increasing its mRNA stability by a p38 MAPK-dependent mechanism; WIN-55 inhibits this effect of TNF-α by inhibiting p38 MAPK via CB2.

By linking the functions of TNF-α, NOS and cannabinoid in DRG neurons, this study adds new insights into the molecular mechanisms underlying the pharmacologic effects of cannabinoids on neuropathic pain as well as into the pathophysiology of neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/29786105

https://www.spandidos-publications.com/10.3892/ijmm.2018.3687

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