Antinociceptive effects of mixtures of mu opioid receptor agonists and cannabinoid receptor agonists in rats: impact of drug and fixed-dose ratio.

Cover image

“Pain is a significant clinical problem, and there is a need for effective pharmacotherapies with fewer adverse effects than currently available drugs (e.g., mu opioid receptor agonists).

Cannabinoid receptor agonists enhance the antinociceptive effects of mu opioid receptor agonists, but it remains unclear which drugs and in what proportion will yield the most effective and safest treatments.

The antinociceptive effects of the mu opioid receptor agonists etorphine and morphine alone and in combination with the cannabinoid receptor agonists Δ9-THC and CP55940 were studied in male Sprague-Dawley rats (n=16) using a warm water tail withdrawal procedure.

The ratio of opioid to cannabinoid (3:1, 1:1, and 1:3) varied for each mixture. Drugs administered alone or as pairwise mixtures of an opioid and a cannabinoid dose-dependently increased tail withdrawal latency. Mixtures with morphine produced supra-additive (CP55940) and additive (Δ9-THC) effects, whereas mixtures with etorphine and either cannabinoid were sub-additive. The interactions were not different among ratios for a particular mixture.

The nature of the interaction between opioids and cannabinoids with regard to antinociceptive effects varies with the particular drugs in the mixture, which can have implications for designing combination therapies for pain.”

https://www.ncbi.nlm.nih.gov/pubmed/29183835

http://www.sciencedirect.com/science/article/pii/S0014299917307719

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Current evidence of cannabinoid-based analgesia obtained in preclinical and human experimental settings.

European Journal of Pain

“Cannabinoids have a long record of recreational and medical use and become increasingly approved for pain therapy. This development is based on preclinical and human experimental research summarized in this review.

Cannabinoid CB1 receptors are widely expressed throughout the nociceptive system. Their activation by endogenous or exogenous cannabinoids modulates the release of neurotransmitters. This is reflected in antinociceptive effects of cannabinoids in preclinical models of inflammatory, cancer and neuropathic pain, and by nociceptive hypersensitivity of cannabinoid receptor-deficient mice.

Cannabis-based medications available for humans mainly comprise Δ9 -tetrahydrocannabinol (THC), cannabidiol (CBD) and nabilone.

During the last 10 years, six controlled studies assessing analgesic effects of cannabinoid-based drugs in human experimental settings were reported. An effect on nociceptive processing could be translated to the human setting in functional magnetic resonance imaging studies that pointed at a reduced connectivity within the pain matrix of the brain. However, cannabinoid-based drugs heterogeneously influenced the perception of experimentally induced pain including a reduction in only the affective but not the sensory perception of pain, only moderate analgesic effects, or occasional hyperalgesic effects. This extends to the clinical setting.

While controlled studies showed a lack of robust analgesic effects, cannabis was nearly always associated with analgesia in open-label or retrospective reports, possibly indicating an effect on well-being or mood, rather than on sensory pain. Thus, while preclinical evidence supports cannabinoid-based analgesics, human evidence presently provides only reluctant support for a broad clinical use of cannabinoid-based medications in pain therapy.

SIGNIFICANCE:

Cannabinoids consistently produced antinociceptive effects in preclinical models, whereas they heterogeneously influenced the perception of experimentally induced pain in humans and did not provide robust clinical analgesia, which jeopardizes the translation of preclinical research on cannabinoid-mediated antinociception into the human setting.”

https://www.ncbi.nlm.nih.gov/pubmed/29160600

http://onlinelibrary.wiley.com/doi/10.1002/ejp.1148/abstract?systemMessage=Wiley+Online+Library+usage+report+download+page+will+be+unavailable+on+Friday+24th+November+2017+at+21%3A00+EST+%2F+02.00+GMT+%2F+10%3A00+SGT+%28Saturday+25th+Nov+for+SGT+

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Tingenone, a pentacyclic triterpene, induces peripheral antinociception due to cannabinoid receptors activation in mice.

 Image result for Inflammopharmacology.

“Several works have shown that triterpenes induce peripheral antinociception by activation of cannabinoid receptors and endocannabinoids; besides, several research groups have reported activation of cannabinoid receptors in peripheral antinociception.

The aim of this study was to assess the involvement of the cannabinoid system in the antinociceptive effect induced by tingenone against hyperalgesia evoked by prostaglandin E2 (PGE2) at peripheral level.

The results suggest that tingenone induced a peripheral antinociceptive effect via cannabinoidreceptor activation. Therefore, this study suggests a pharmacological potential for a new analgesic drug.”

https://www.ncbi.nlm.nih.gov/pubmed/28889355

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis.

logo

“Osteoarthritis (OA) is a multifactorial joint disease, which includes joint degeneration, intermittent inflammation, and peripheral neuropathy. Cannabidiol (CBD) is a non-euphoria producing constituent of cannabis that has the potential to relieve pain.

The aim of this study was to determine if CBD is anti-nociceptive in OA, and whether inhibition of inflammation by CBD could prevent the development of OA pain and joint neuropathy.

The therapeutic and prophylactic effects of peripheral CBD (100-300μg) were assessed. In end stage OA, CBD dose-dependently decreased joint afferent firing rate, and increased withdrawal threshold and weight bearing (p<0.0001; n=8). Acute, transient joint inflammation was reduced by local CBD treatment (p<0.0001; n=6). Prophylactic administration of CBD prevented the development of MIA-induced joint pain at later time points (p<0.0001; n=8), and was also found to be neuroprotective (p<0.05; n=6-8).

The data presented here indicate that local administration of CBD blocked OA pain. Prophylactic CBD treatment prevented the later development of pain and nerve damage in these OA joints.

These findings suggest that CBD may be a safe, useful therapeutic for treating OA joint neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/28885454             https://insights.ovid.com/crossref?an=00006396-900000000-99152

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Anti-nociceptive interactions between opioids and a cannabinoid receptor 2 agonist in inflammatory pain.

SAGE Journals

“The cannabinoid 1 receptor and cannabinoid 2 receptor can both be targeted in the treatment of pain; yet, they have some important differences. Cannabinoid 1 receptor is expressed at high levels in the central nervous system, whereas cannabinoid 2 receptor is found predominantly, although not exclusively, outside the central nervous system. The objective of this study was to investigate potential interactions between cannabinoid 2 receptor and the mu-opioid receptor in pathological pain. The low level of adverse side effects and lack of tolerance for cannabinoid 2 receptor agonists are attractive pharmacotherapeutic traits. This study assessed the anti-nociceptive effects of a selective cannabinoid 2 receptor agonist (JWH-133) in pathological pain using mice subjected to inflammatory pain using the formalin test. Furthermore, we examined several ways in which JWH-133 may interact with morphine. JWH-133 produces dose-dependent anti-nociception during both the acute and inflammatory phases of the formalin test. This was observed in both male and female mice. However, a maximally efficacious dose of JWH-133 (1 mg/kg) was not associated with somatic withdrawal symptoms, motor impairment, or hypothermia. After eleven once-daily injections of 1 mg/JWH-133, no tolerance was observed in the formalin test. Cross-tolerance for the anti-nociceptive effects of JWH-133 and morphine were assessed to gain insight into physiologically relevant cannabinoid 2 receptor and mu-opioid receptor interaction. Mice made tolerant to the effects of morphine exhibited a lower JWH-133 response in both phases of the formalin test compared to vehicle-treated morphine-naïve animals. However, repeated daily JWH-133 administration did not cause cross-tolerance for morphine, suggesting opioid and cannabinoid 2 receptor cross-tolerance is unidirectional. However, preliminary data suggest co-administration of JWH-133 with morphine modestly attenuates morphine tolerance. Isobolographic analysis revealed that co-administration of JWH-133 and morphine has an additive effect on anti-nociception in the formalin test. Overall these findings show that cannabinoid 2 receptor may functionally interact with mu-opioid receptor to modulate anti-nociception in the formalin test.”

https://www.ncbi.nlm.nih.gov/pubmed/28879802

http://journals.sagepub.com/doi/10.1177/1744806917728227

 

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

The Endogenous Cannabinoid System: A Budding Source of Targets for Treating Inflammatory and Neuropathic Pain.

Image result for Neuropsychopharmacology

“A great need exists for the development of new medications to treat pain resulting from various disease states and types of injury. Given that the endogenous cannabinoid (ie, endocannabinoid) system modulates neuronal and immune cell function, both of which play key roles in pain, therapeutics targeting this system hold promise as novel analgesics.

Potential therapeutic targets include the cannabinoid receptors, type 1 and 2, as well as biosynthetic and catabolic enzymes of the endocannabinoids N-arachidonoylethanolamine and 2-arachidonoylglycerol. Notably, cannabinoid receptor agonists as well as inhibitors of endocannabinoid-regulating enzymes fatty acid amide hydrolase and monoacylglycerol lipase produce reliable antinociceptive effects, and offer opioid-sparing antinociceptive effects in myriad preclinical inflammatory and neuropathic pain models.

Emerging clinical studies show that ‘medicinal’ cannabis or cannabinoid-based medications relieve pain in human diseases, such as cancer, multiple sclerosis, and fibromyalgia.

Here, we examine the preclinical and clinical evidence of various endocannabinoid system targets as potential therapeutic strategies for inflammatory and neuropathic pain conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/28857069

https://www.nature.com/npp/journal/vaop/naam/abs/npp2017204a.html

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Cannabinoids and Pain: Sites and Mechanisms of Action.

Advances in Pharmacology

“The endocannabinoid system, consisting of the cannabinoid1 receptor (CB1R) and cannabinoid2 receptor (CB2R), endogenous cannabinoid ligands (endocannabinoids), and metabolizing enzymes, is present throughout the pain pathways. Endocannabinoids, phytocannabinoids, and synthetic cannabinoid receptor agonists have antinociceptive effects in animal models of acute, inflammatory, and neuropathic pain. CB1R and CB2R located at peripheral, spinal, or supraspinal sites are important targets mediating these antinociceptive effects. The mechanisms underlying the analgesic effects of cannabinoids likely include inhibition of presynaptic neurotransmitter and neuropeptide release, modulation of postsynaptic neuronal excitability, activation of the descending inhibitory pain pathway, and reductions in neuroinflammatory signaling. Strategies to dissociate the psychoactive effects of cannabinoids from their analgesic effects have focused on peripherally restricted CB1R agonists, CB2R agonists, inhibitors of endocannabinoid catabolism or uptake, and modulation of other non-CB1R/non-CB2R targets of cannabinoids including TRPV1, GPR55, and PPARs. The large body of preclinical evidence in support of cannabinoids as potential analgesic agents is supported by clinical studies demonstrating their efficacy across a variety of pain disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/28826543

http://www.sciencedirect.com/science/article/pii/S1054358917300443?via%3Dihub

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Antinociceptive effects of HUF-101, a fluorinated cannabidiol derivative.

Cover image

“Cannabidiol (CBD) is a phytocannabinoid with multiple pharmacological effects and several potential therapeutic properties. Its low oral bioavailability, however, can limit its clinical use.

Preliminary results indicate that fluorination of the CBD molecule increases its pharmacological potency. Here, we investigated whether HUF-101 (3, 10, and 30mg/kg), a fluorinated CBD analogue, would induce antinociceptive effects.

These findings show that HUF-101 produced antinociceptive effects at lower doses than CBD, indicating that the addition of fluoride improved its pharmacological profile. Furthermore, some of the antinociceptive effects of CBD and HUF-101 effects seem to involve the activation of CB1 and CB2 receptors.”

https://www.ncbi.nlm.nih.gov/pubmed/28720466

http://www.sciencedirect.com/science/article/pii/S0278584617302233

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Comparative antinociceptive effect of arachidonylcyclopropylamide, a cannabinoid 1 receptor agonist & lignocaine, a local anaesthetic agent, following direct intrawound administration in rats.

 Image result for Indian J Med Res.

“Treatment of inflammatory pain with opioids is accompanied by unpleasant and, at times, life-threatening side effects.

Cannabis produces antinociception as well as psychotropic effects. It was hypothesized that peripheral cannabinoid receptors outside the central nervous system could be selectively activated for relief of pain.

This study was undertaken to measure the antinociceptive effect of type 1 cannabinoid receptor (CB1r) agonist arachidonylcyclopropylamide (ACPA) in a rat model of inflammatory pain after intrawound administration and the effects were compared with lignocaine.

Lignocaine attenuated evoked pain behaviour whereas ACPA decreased guarding score. This difference was likely due to blockade of sodium ion channels and the activation of peripheral CB1r, respectively. Central side effects were absent after ACPA treatment. Further studies need to be done to assess the effect of ACPA treatment in clinical conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/28361827

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous

Cannabinoids Ameliorate Pain and Reduce Disease Pathology in Cerulein-Induced Acute Pancreatitis

Image result for gastroenterology journal

“The endocannabinoid system has been identified as a major regulator of physiological and pathological processes, such as pain, inflammation, cell growth, cell death, and as a regulator of diverse gastrointestinal functions, such as intestinal motility and secretion.

Although cannabinoid-induced analgesia was initially primarily attributed to the activation of cannabinoid receptor 1 (CB1) in the nervous system, later studies demonstrated a contribution of cannabinoid receptor 2 (CB2), localized peripherally on immune cells as well as in the nervous system.

A complex interplay between endogenously released cannabinoids, such as anandamide or 2-arachidonoylglycerol, and their receptors both on inflammatory cells and neurons is involved in modulation of inflammatory pain.

In this article, we demonstrate the in vivo significance and therapeutic potential of cannabinoids in inflammation and pain associated with pancreatitis using human specimens and mouse models as test systems.

Our results are more in line with a recent study reporting a protective role for the endogenous cannabinoid system against colonic inflammation in a mouse model of experimental colitis.

Consistent with the above, we now show that acute pancreatitis, a visceral inflammatory disease in humans, is associated with an activation of the endocannabinoid system.

In humans, acute pancreatitis is associated with up-regulation of ligands as well as receptors of the endocannabinoid system in the pancreas. Furthermore, our results suggest a therapeutic potential for cannabinoids in abolishing pain associated with acute pancreatitis and in partially reducing inflammation and disease pathology in the absence of adverse side effects.

Because management of visceral inflammatory diseases should ideally include antinociceptive as well as anti-inflammatory components, our results lay a basis for testing the therapeutic value of cannabinoids as supplements to conventional analgesic therapy.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268094/

Facebook Twitter Pinterest Stumbleupon Tumblr Posterous