Category Archives: Neuropathic Pain

The Analgesic Potential of Cannabinoids

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“Cannabinoids are derivatives of Cannabis sativa, the hemp plant, which evolved in the temperate regions of Central Asia. Cannabis was used as a medicine in ancient China (2700 BC) and India (1000 BC). Historically and anecdotally cannabinoids have been used as analgesic agents.

In recent years, there has been an escalating interest in developing cannabis-derived medications to treat severe pain. This review provides an overview of the history of cannabis use in medicine, cannabinoid signaling pathways, and current data from preclinical as well as clinical studies on using cannabinoids as potential analgesic agents. Clinical and experimental studies show that cannabis-derived compounds act as anti-emetic, appetite modulating and analgesic agents.

Since opioids are the only therapy for severe pain, analgesic ability of cannabinoids may provide a much-needed alternative to opioids. Moreover, cannabinoids act synergistically with opioids and act as opioid sparing agents, allowing lower doses and fewer side effects from chronic opioid therapy. Thus, rational use of cannabis based medications deserves serious consideration to alleviate the suffering of patients due to severe pain.”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3728280/

Single and combined effects of delta9 -tetrahydrocannabinol and cannabidiol in a mouse model of chemotherapy-induced neuropathic pain.

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British Journal of Pharmacology

“It has been suggested that the non-psychoactive phytocannabinoid cannabidiol (CBD) can impact the pharmacological effects of delta-9-tetrahydrocannabinol (THC). We tested the hypothesis that CBD and THC would significantly mitigate mechanical sensitivity in a mouse model of paclitaxel-induced neuropathic pain, and that CBD+THC combinations would produce synergistic effects. We also tested the hypothesis that CBD would attenuate oxaliplatin- and vincristine- induced mechanical sensitivity.

KEY RESULTS:

Both CBD and THC alone attenuated mechanical allodynia in mice treated with paclitaxel. Very low ineffective doses of CBD and THC were synergistic when given in combination. CBD also attenuated oxaliplatin- but not vincristine-induced mechanical sensitivity, while THC significantly attenuated vincristine- but not oxaliplatin-induced mechanical sensitivity. The low dose combination significantly attenuated oxaliplatin- but not vincristine-induced mechanical sensitivity.

CONCLUSIONS AND IMPLICATIONS:

CBD may be potent and effective at preventing the development of CIPN, and its clinical utility may be enhanced by co-administration of low doses of THC. These treatment strategies would increase the therapeutic window of Cannabis-based pharmacotherapies.”

https://www.ncbi.nlm.nih.gov/pubmed/28548225

http://onlinelibrary.wiley.com/doi/10.1111/bph.13887/abstract

Selective Cannabinoids for Chronic Neuropathic Pain: A Systematic Review and Meta-analysis.

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“There is a lack of consensus on the role of selective cannabinoids for the treatment of neuropathic pain (NP). Guidelines from national and international pain societies have provided contradictory recommendations. The primary objective of this systematic review and meta-analysis (SR-MA) was to determine the analgesic efficacy and safety of selective cannabinoids compared to conventional management or placebo for chronic NP.

METHODS:

We reviewed randomized controlled trials that compared selective cannabinoids (dronabinol, nabilone, nabiximols) with conventional treatments (eg, pharmacotherapy, physical therapy, or a combination of these) or placebo in patients with chronic NP because patients with NP may be on any of these therapies or none if all standard treatments have failed to provide analgesia and or if these treatments have been associated with adverse effects. MEDLINE, EMBASE, and other major databases up to March 11, 2016, were searched. Data on scores of numerical rating scale for NP and its subtypes, central and peripheral, were meta-analyzed. The certainty of evidence was classified using the Grade of Recommendations Assessment, Development, and Evaluation approach.

RESULTS:

Eleven randomized controlled trials including 1219 patients (614 in selective cannabinoid and 605 in comparator groups) were included in this SR-MA. There was variability in the studies in quality of reporting, etiology of NP, type and dose of selective cannabinoids. Patients who received selective cannabinoids reported a significant, but clinically small, reduction in mean numerical rating scale pain scores (0-10 scale) compared with comparator groups (-0.65 points; 95% confidence interval, -1.06 to -0.23 points; P = .002, I = 60%; Grade of Recommendations Assessment, Development, and Evaluation: weak recommendation and moderate-quality evidence). Use of selective cannabinoids was also associated with improvements in quality of life and sleep with no major adverse effects.

CONCLUSIONS:

Selective cannabinoids provide a small analgesic benefit in patients with chronic NP. There was a high degree of heterogeneity among publications included in this SR-MA. Well-designed, large, randomized studies are required to better evaluate specific dosage, duration of intervention, and the effect of this intervention on physical and psychologic function.”

 https://www.ncbi.nlm.nih.gov/pubmed/28537982
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Combined cannabinoid therapy via an oromucosal spray.

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“Extensive basic science research has identified the potential therapeutic benefits of active compounds extracted from the Cannabis sativa L. plant (the cannabinoids). It is recognized that a significant proportion of patients suffering with the debilitating symptoms of pain and spasticity in multiple sclerosis or other conditions smoke cannabis despite the legal implications and stigma associated with this controlled substance. GW Pharmaceuticals have developed Sativex (GW- 1000-02), a combined cannabinoid medicine that delivers and maintains therapeutic levels of two principal cannabinoids, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), via an oromucosal pump spray, that aims to minimize psychotropic side effects.”  https://www.ncbi.nlm.nih.gov/pubmed/16969427

“Sativex has proved to be well tolerated and successfully self-administered and self-titrated in both healthy volunteers and patient cohorts. Clinical assessment of this combined cannabinoid medicine has demonstrated efficacy in patients with intractable pain (chronic neuropathic pain, pain due to brachial plexus nerve injury, allodynic peripheral neuropathic pain and advanced cancer pain), rheumatoid arthritis and multiple sclerosis (bladder problems, spasticity and central pain), with no significant intoxication-like symptoms, tolerance or withdrawal syndrome.”  https://journals.prous.com/journals/servlet/xmlxsl/pk_journals.xml_summaryn_pr?p_JournalId=4&p_RefId=1021517

“Sativex(®) (nabiximols, USAN name) oromucosal spray contains the two main active constituents of Cannabis sativa, tetrahydrocannabinol and cannabidiol in a 1:1 molecular ratio, and acts as an endocannabinoid system modulator.”  https://www.ncbi.nlm.nih.gov/pubmed/21449855

“Abuse potential and psychoactive effects of δ-9-tetrahydrocannabinol and cannabidiol oromucosal spray (Sativex), a new cannabinoid medicine. Evidence to date suggests that abuse or dependence on Sativex is likely to occur in only a very small proportion of recipients.” https://www.ncbi.nlm.nih.gov/pubmed/21542664

Cannabinoid CB2 receptor ligand profiling reveals biased signalling and off-target activity

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“The cannabinoid CB2 receptor (CB2R) represents a promising therapeutic target for various forms of tissue injury and inflammatory diseases. There is a great interest in the development of selective type-2 cannabinoid receptor (CB2R) agonists as potential drug candidates for various pathophysiological conditions, which include chronic and inflammatory pain, pruritus, diabetic neuropathy and nephropathy, liver cirrhosis, and protective effects after ischaemic-reperfusion injury.” https://www.nature.com/articles/ncomms13958

“Pain relief without the high. Researchers at Leiden University led by Mario van der Stelt (Leiden Institute for Chemistry) have set ‘gold standards’ for developing new painkillers based on the medicinal effects of cannabis.”  https://www.sciencedaily.com/releases/2017/01/170104103916.htm

ScienceDaily

Antihyperalgesic Activities of Endocannabinoids in a Mouse Model of Antiretroviral-Induced Neuropathic Pain.

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“Nucleoside reverse transcriptase inhibitors (NRTIs) are the cornerstone of the antiretroviral therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). However, their use is sometimes limited by the development of a painful sensory neuropathy, which does not respond well to drugs.

Smoked cannabis has been reported in clinical trials to have efficacy in relieving painful HIV-associated sensory neuropathy.

The aim of this study was to evaluate whether the expression of endocannabinoid system molecules is altered during NRTI-induced painful neuropathy, and also whether endocannabinoids can attenuate NRTI-induced painful neuropathy.

Conclusion: These data show that ddC induces thermal hyperalgesia, which is associated with dysregulation of the mRNA expression of some endocannabinoid system molecules. The endocannabinoids AEA and 2-AG have antihyperalgesic activity, which is dependent on cannabinoid receptor and GPR55 activation. Thus, agonists of cannabinoid receptors and GPR55 could be useful therapeutic agents for the management of NRTI-induced painful sensory neuropathy.”

https://www.ncbi.nlm.nih.gov/pubmed/28373843

[Role of cannabinoid receptor 1-mediated synaptic plasticity in neuropathic pain and associated depression].

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“Neuropathic pain is a class of pain caused by an injury or diseases of the somatosensory system and characterized by spontaneous pain, allodynia, and hyperalgesia. It is well established that central sensitization is one of the key mechanisms underlying the development and maintenance of neuropathic pain. Cannabinoid receptor 1 (CB1R) of endocannabinoid system modulates synaptic transmission, regulates synaptic plasticity, inhibits central sensitization, and thus attenuates neuropathic pain. Recent studies have shown that activation of CB1R also involves in the relief of neuropathic pain-induced depression.” https://www.ncbi.nlm.nih.gov/pubmed/28364110

Cannabis Reduces Opioid Dose in the Treatment of Chronic Non-Cancer Pain

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“Cannabinoids block pain responses in virtually every laboratory pain model tested.

In models of acute or physiological pain, cannabinoids are highly effective against thermal, mechanical, and chemical pain, and are comparable to opioids in potency and efficacy.1 In models of chronic pain, cannabinoids exhibit efficacy in the modulation of both inflammatory2 and neuropathic pain.3

Recent reviews describe an endogenous cannabinoid system involved in pain modulation that produces analgesia through the same brainstem circuitry involved in opioid analgesia.1., 4., 5., 6. Although co-administration of Δ-9-tetrahydrocannabinol (THC) with μ opioid agonists can potentiate the antinociceptive effects of each agent, an opioid is not required for cannabinoid analgesia.5., 6. Co-administration of a cannabinoid may lead to a lower opioid requirement. In an N-of-1 trial, oral THC reduced the pain of familial Mediterranean fever such that the use of breakthrough opioid for pain relief decreased significantly.7

Recently, in Canada, the Medical Marijuana Access Program allows patients to apply to Health Canada for access to dried cannabis for medicinal purposes. Although smoked cannabis is not an ideal delivery system, it is efficient and results in plasma concentration curves parallel to those seen after intravenous administration.8 We present three patients who used small doses of smoked marijuana in combination with an opioid.

These cases are consistent with preclinical work demonstrating that cannabinoids exhibit analgesic effects and may potentiate the antinociceptive effects of opioids. These patients were able to decrease the dose of opioid by 60–100% as compared to before the regular use of smoked marijuana. With the introduction of smoked marijuana, each patient reported better pain control.

Unfortunately, the source of smoked marijuana used by patients, and the percentage of THC in it, is unknown. All patients reported previous exposure to cannabis at some time in their lives before the onset of their pain, and the relevance of this experience also is unknown. Standardized measures of pain were not used, and the information presented was based on the patients’ verbal report when they presented for follow-up appointments at the Pain Management Unit. Nonetheless, these cases suggest that further research regarding the role of cannabinoids as analgesics and the combination of cannabinoids with opioids in the control of pain is needed.”

http://www.jpsmjournal.com/article/S0885-3924(03)00142-8/fulltext

Allodynia Lowering Induced by Cannabinoids and Endocannabinoids (ALICE).

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“Neuropathic pain is a neurological disorder that strongly affects the quality of life of patients. The molecular and cellular mechanisms at the basis of the neuropathic pain establishment still need to be clarified. Among the neuromodulators involved in the pathological pain pathways, endocannabinoid system could be deeply involved in both neuronal and non-neuronal mechanisms responsible for the appearance of tactile allodynia. Indeed, the function and dysfunction of this complex system in the molecular and cellular mechanisms of chronic pain induction and maintenance has been widely studied over the last two decades. In this review article, we highlighted the possible modulation of the endocannabinoid system in the neuronal, glial and microglial modulation in neuropathic pain treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/28237514

Evaluation of cannabinoids concentration and stability in standardized preparations of cannabis tea and cannabis oil by ultra-high performance liquid chromatography tandem mass spectrometry.

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“Cannabis has been used since ancient times to relieve neuropathic pain, to lower intraocular pressure, to increase appetite and finally to decrease nausea and vomiting.

The combination of the psychoactive cannabis alkaloid Δ9-tetrahydrocannabinol (THC) with the non-psychotropic alkaloids cannabidiol (CBD) and cannabinol (CBN) demonstrated a higher activity than THC alone.

Extraction efficiency of oil was significantly higher than that of water with respect to the different cannabinoids.

Fifteen minutes boiling was sufficient to achieve the highest concentrations of cannabinoids in the cannabis tea solutions.

As the first and most important aim of the different cannabis preparations is to guarantee therapeutic continuity in treated individuals, a strictly standardized preparation protocol is necessary to assure the availability of a homogeneous product of defined stability.”

https://www.ncbi.nlm.nih.gov/pubmed/28207408