Opioid-sparing Effect of Cannabinoids: A Systematic Review and Meta-analysis.

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“Cannabinoids, when co-administered with opioids, may enable reduced opioid doses without loss of analgesic efficacy (ie an opioid-sparing effect). The aim of this study was to conduct a systematic review to determine the opioid-sparing potential of cannabinoids.

Eligible studies included pre-clinical and clinical studies for which the outcome was either analgesia or opioid dose requirements. Clinical studies included controlled studies and case series. We searched Scopus, Cochrane Database of Systematic Reviews, Medline, and Embase. Nineteen pre-clinical and nine clinical studies met the search criteria. Seventeen of the 19 pre-clinical studies provided evidence of synergistic effects from opioid and cannabinoid co-administration. Our meta-analysis of pre-clinical studies indicated that the median effective dose (ED50) of morphine administered in combination with delta-9-tetrahydrocannabinol (delta-9-THC) is 3.6 times lower (95% CI 1.95, 6.76; n=6) than the ED50 of morphine alone. In addition, the ED50 for codeine administered in combination with delta-9-THC was 9.5 times lower (95% CI 1.6, 57.5, n=2) than the ED50 of codeine alone. One case series (n=3) provided very low-quality evidence of a reduction in opioid requirements with cannabinoid co-administration. Larger controlled clinical studies showed some clinical benefits of cannabinoids; however, opioid dose changes were rarely reported and mixed findings were observed for analgesia.

In summary, pre-clinical studies provide robust evidence of the opioid-sparing effect of cannabinoids, while one of the nine clinical studies identified provided very low-quality evidence of such an effect. Prospective high-quality controlled clinical trials are required to determine the opioid-sparing effect of cannabinoids.”


Fatty-acid-binding protein inhibition produces analgesic effects through peripheral and central mechanisms.

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“Fatty-acid-binding proteins (FABPs) are intracellular carriers for endocannabinoids, N-acylethanolamines, and related lipids. Previous work indicates that systemically administered FABP5 inhibitors produce analgesia in models of inflammatory pain. It is currently not known whether FABP inhibitors exert their effects through peripheral or central mechanisms. Here, we examined FABP5 distribution in dorsal root ganglia and spinal cord and examined the analgesic effects of peripherally and centrally administered FABP5 inhibitors.

Results: Immunofluorescence revealed robust expression of FABP5 in lumbar dorsal root ganglia. FABP5 was distributed in peptidergic calcitonin gene-related peptide-expressing dorsal root ganglia and non-peptidergic isolectin B4-expressing dorsal root ganglia. In addition, the majority of dorsal root ganglia expressing FABP5 also expressed transient receptor potential vanilloid 1 (TRPV1) and peripherin, a marker of nociceptive fibers. Intraplantar administration of FABP5 inhibitors reduced thermal and mechanical hyperalgesia in the complete Freund’s adjuvant model of chronic inflammatory pain. In contrast to its robust expression in dorsal root ganglia, FABP5 was sparsely distributed in the lumbar spinal cord and intrathecal administration of FABP inhibitor did not confer analgesic effects. Administration of FABP inhibitor via the intracerebroventricular (i.c.v.) route reduced thermal hyperalgesia. Antagonists of peroxisome proliferator-activated receptor alpha blocked the analgesic effects of peripherally and i.c.v. administered FABP inhibitor while antagonism of cannabinoid receptor 1 blocked the effects of peripheral FABP inhibition and a TRPV1 antagonist blocked the effects of i.c.v. administered inhibitor. Although FABP5 and TRPV1 were co-expressed in the periaqueductal gray region of the brain, which is known to modulate pain, knockdown of FABP5 in the periaqueductal gray using adeno-associated viruses and pharmacological FABP5 inhibition did not produce analgesic effects.

Conclusions: This study demonstrates that FABP5 is highly expressed in nociceptive dorsal root ganglia neurons and FABP inhibitors exert peripheral and supraspinal analgesic effects. This indicates that peripherally restricted FABP inhibitors may serve as a new class of analgesic and anti-inflammatory agents.”


Effects of JWH015 in cytokine secretion in primary human keratinocytes and fibroblasts and its suitability for topical/transdermal delivery.

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“JWH015 is a cannabinoid (CB) receptor type 2 agonist that produces immunomodulatory effects. Since skin cells play a key role in inflammatory conditions and tissue repair, we investigated the ability of JWH015 to promote an anti-inflammatory and pro-wound healing phenotype in human primary skin cells.

The expression of CB1 and CB2 receptors (mRNA) and the production of pro- and anti-inflammatory factors enhanced in keratinocytes and fibroblasts following lipopolysaccharide stimulation. JWH015 reduced the concentration of major pro-inflammatory factors (IL-6 and MCP-1) and increased the concentration of a major anti-inflammatory factor (TGF-β) in lipopolysaccharide-stimulated cells.

JWH015 induced a faster scratch gap closure. These JWH015’seffects were mainly modulated through both CB1 and CB2 receptors. Topically administered JWH015 was mostly retained in the skin and displayed a sustained and low level of transdermal permeation.

Our findings suggest that targeting keratinocytes and fibroblasts with cannabinoid drugs could represent a therapeutic strategy to resolve peripheral inflammation and promote tissue repair.”

Overactivation of the endocannabinoid system alters the anti-lipolytic action of insulin in mouse adipose tissue.

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“Evidence has accumulated that obesity-related metabolic dysregulation is associated with overactivation of the endocannabinoid system (ECS), which involves cannabinoid receptor 1 (CB1R), in peripheral tissues, including adipose tissue (AT).

The functional consequences of CB1R activation on AT metabolism remain unclear. Since excess fat mobilization is considered an important primary event contributing to the onset of insulin resistance, we combined in vivo and in vitro experiments to investigate whether activation of ECS could alter the lipolytic rate.

For this purpose, the appearance of plasma glycerol was measured in wild-type and CB1R-/- mice after acute anandamide administration or inhibition of endocannabinoid degradation by JZL195. Additional experiments were conducted on rat AT explants to evaluate the direct consequences of ECS activation on glycerol release and signaling pathways.

Treatments stimulated glycerol release in mice fasted for 6 h and injected with glucose but not in 24-h fasted mice or in CB1R-/-suggesting that the effect was dependent on plasma insulin levels and mediated by CB1R. We concomitantly observed that Akt cascade activity was decreased, indicating an alteration of the anti-lipolytic action of insulin.

Similar results were obtained with tissue explants exposed to anandamide, thus identifying CB1R of AT as a major target.

This study indicates the existence of a functional interaction between CB1R and lipolysis regulation in AT. Further investigation is needed to test whether the elevation of ECS tone encountered in obesity is associated with excess fat mobilization contributing to ectopic fat deposition and related metabolic disorders.”


Antidiabetic, antidyslipidemic and toxicity profile of ENV-2: A potent pyrazole derivative against diabetes and related diseases.

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“Diabetes is a major health problem and a predisposition factor for further degenerative complications and, therefore, novel therapies are urgently needed. Currently, cannabinoid receptor 1 (CB1 receptor) antagonists have been considered as promissory entities for metabolic disorders treatment.

Accordingly, the purpose of this work was the evaluation of the sub-acute antidiabetic, anti-hyperglycemic, antidyslipidemic and toxicological profile of ENV-2, a potent hypoglycemic and antioxidant CB1 receptor antagonist.

In this study, ENV-2 showed a pronounced anti-hyperglycemic effect even at a dose of 5mg/kg (P< 0.001) in a glucose tolerance test on normoglycemic rats. Moreover, after administration of ENV-2 (16mg/kg) to diabetic rats, a prominent antidiabetic activity was observed (P< 0.001), which was higher than glibenclamide.

Sub-acute treatment (10 days) of ENV-2 resulted in a significant reduction of plasma glucose (P< 0.001). Also, the levels of peripheral lipids were improved; blood triacylglycerols (TG) and cholesterol (CHOL) were diminished (P< 0.001). In addition, it was found that ENV-2 reduced IL-1β and IL-18 mRNA expression in adipose tissue (P< 0.05). Due to the satisfactory outcomes, we were interested in evaluating the toxicity of ENV-2 in both acute and sub-chronic approaches. Regarding the acute administration, the compound resulted to be non-toxic and was grouped in category 5 according to OECD. It was also found that sub-chronic administration did not increase the size of the studied organs, while no structural damage was observed in heart, lung, liver and kidney tissues. Finally, neither AST nor ALT damage hepatic markers were augmented.”


Cannabinoid receptor 1 contributes to sprouted innervation in endometrial ectopic growth through mitogen-activated protein kinase activation.

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“The endocannabinoid system regulates neurite outgrowth and neurogenesis during development of the central nervous system.

Cannabinoid receptor 1 (CB1R) is expressed in neurons, including the somata and fibers, that innervate the endometrial ectopic cyst in rats.


This finding may provide a new therapeutic target for patients with endometriosis.”


2-Arachidonoylglycerol ameliorates inflammatory stress-induced insulin resistance in cardiomyocytes.

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“Several studies have linked impaired glucose uptake and insulin resistance (IR) to functional impairment of the heart. Recently, endocannabinoids have been implicated in cardiovascular disease. However, the mechanisms involving endocannabinoid signaling, glucose uptake and IR in cardiomyocytes are understudied.

Here, we report the endocannabinoid 2-Arachidonoylglycerol (2-AG) via stimulation of cannabinoid type-1 (CB1) receptor and Ca2+/Calmodulin-dependent protein kinase β (CaMKKβ) activates AMPK leading to increased glucose uptake. Interestingly, we have observed that the mRNA expression of CB1 and CB2 receptors was decreased in diabetic mice, indicating reduced endocannabinoid signaling in diabetic heart. We further establish that TNFα induces IR in cardiomyocytes.

Treatment with 2-AG suppresses TNFα-induced pro-inflammatory markers, and improves IR and glucose uptake. Conversely, pharmacological inhibition or knockdown of AMPK attenuates the anti-inflammatory effect and reversal of IR elicited by 2-AG. Additionally, in human embryonic stem cell-derived cardiomyocytes challenged with TNFα or free fatty acid (FFA), we demonstrate that 2-AG improves insulin sensitivity and glucose uptake.

In conclusion, 2-AG abates inflammatory responses, increases glucose uptake and overcomes IR in an AMPK-dependent manner in cardiomyocytes.”


Rimonabant, a selective cannabinoid1 receptor antagonist, protects against light-induced retinal degeneration in vitro and in vivo.

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“The endocannabinoid system is involved in some neurodegenerative diseases such as Alzheimer’s disease. An endogenous constellation of proteins related to cannabinoid1 receptor signaling, including free fatty acids, diacylglycerol lipase, and N-acylethanolamine-hydrolyzing acid amidase, are localized in the murine retina. Moreover, the expression levels of endogenous agonists of cannabinoid receptors are changed in the vitreous fluid.

However, the role of the endocannabinoid system in the retina, particularly in the light-induced photoreceptor degeneration, remains unknown. Therefore, we investigated involvement of the cannabinoid1 receptor in light-induced retinal degeneration using in vitro and in vivo models.

Rimonabant suppressed light-induced photoreceptor cell death. Cannabinoid1 receptor expression was upregulated by light exposure. Treatment with rimonabant improved both a- and b-wave amplitudes and the thickness of the outer nuclear layer.

These results suggest that the cannabinoid1 receptor is involved in light-induced retinal degeneration and it may represent a therapeutic target in the light-induced photoreceptor degeneration related diseases.”


Hepatic expressions of cannabinoid receptors CB1 and CB2 correlate with the fibrogenesis in patients with chronic hepatitis B.

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“The endocannabinoid system is involved in the pathogenesis of liver fibrosis. However, most of the findings come from experiment researches on animal model or clinical trial on chronic hepatitis C.

The roles of cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) in hepatofibrosis on patients with chronic hepatitis B(CHB) have not been studied universally. This study aimed to explore the relationship between liver fibrosis and expressions of CB1 and CB2 on patients with CHB.

The hepatic expressions of CB1 and CB2 play important roles during the progression of fibrosis induced by CHB. Endogenous activation of CB1 receptors in patients with CHB enhances fibrogenesis by direct effect on activated HSCs.”


Delta-9-Tetrahydrocannabinol/Cannabidiol Oromucosal Spray (Sativex®): A Review in Multiple Sclerosis-Related Spasticity.

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“Delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray (THC/CBD, Sativex®, nabiximols) is available in numerous countries worldwide for the treatment of multiple sclerosis (MS)-related moderate to severe spasticity in patients who have not responded adequately to other anti-spasticity medication and who demonstrate clinically significant improvement in spasticity-related symptoms during an initial trial of therapy.

Twelve weeks’ therapy with THC/CBD improved MS-related spasticity in patients with an inadequate response to other anti-spasticity agents who had undergone a successful initial trial of THC/CBD therapy, according to the results of a pivotal phase 3 trial.

Improvements in spasticity were maintained in the longer term with THC/CBD with no evidence of dose tolerance, and results of real-world studies confirm the effectiveness of THC/CBD in everyday clinical practice.

Improvements in health-related quality of life and activities of daily living were also seen with THC/CBD.

THC/CBD is generally well tolerated; adverse effects such as dizziness may occur whilst the THC/CBD dosage is being optimized.

THC/CBD has low abuse potential and a low risk of psychoactive effects.

In conclusion, THC/CBD oromucosal spray is a useful option for the treatment of MS-related spasticity not completely relieved with current anti-spasticity medication.”