Antinociception mechanisms of action of cannabinoid-based medicine: an overview for anesthesiologists and pain physicians

MP-13, a novel chimeric peptide of morphiceptin and pepcan-9, produces potent antinociception with limited side effects

Pharmacological investigations have substantiated the potential of bifunctional opioid/cannabinoid agonists in delivering potent analgesia while minimizing adverse reactions. Peptide modulators of cannabinoid receptors, known as pepcans, have been investigated before. In this study, we designed a series of chimeric peptides based on pepcans and morphiceptin (YPFP-NH2). Here, we combined injections of pepcans and morphiceptin to investigate the combination treatment of opioids and cannabis and compared the analgesic effect with chimeric compounds. Subsequently, we employed computational docking to screen the compounds against opioid and cannabinoid receptors, along with an acute pain model, to identify the most promising peptide. Among these peptides, MP-13, a morphiceptin and pepcan-9 (PVNFKLLSH) construct, exhibited superior supraspinal analgesic efficacy in the tail-flick test, with an ED50 value at 1.43 nmol/mouse, outperforming its parent peptides and other chimeric analogs. Additionally, MP-13 displayed potent analgesic activity mediated by mu-opioid receptor (MOR), delta-opioid receptor (DOR), and cannabinoid type 1 (CB1) receptor pathways. Furthermore, MP-13 did not induce psychological dependence and gastrointestinal motility inhibition at the effective analgesic doses, and it maintained non-tolerance-forming antinociception throughout a 7-day treatment regimen, with an unaltered count of microglial cells in the periaqueductal gray region, supporting this observation. Moreover, intracerebroventricular administration of MP-13 demonstrated dose-dependent antinociception in murine models of neuropathic, inflammatory, and visceral pain. Our findings provide promising insights for the development of opioid/cannabinoid peptide agonists, addressing a crucial gap in the field and holding significant potential for future research and development. PERSPECTIVE: This article offers insights into the combination treatment of pepcans with morphiceptin. Among the chimeric peptides, MP-13 exhibited potent analgesic effects in a series of preclinical pain models with a favorable side-effect profile.

Peripherally restricted cannabinoid and mu-opioid receptor agonists synergistically attenuate neuropathic mechanical hypersensitivity in mice

ABSTRACT

Many medications commonly used to treat neuropathic pain are associated with significant, dose-limiting adverse effects, including sedation, dizziness, and fatigue. These adverse effects are due to the activity of these medications within the central nervous system. The objective of this work was to investigate the interactions between peripherally restricted cannabinoid receptor and mu-opioid receptor (MOR) agonists on ongoing and evoked neuropathic pain behaviors in mouse models. RNAscope analysis of cannabinoid receptor type 1 (CB1R) and MOR mRNA demonstrated that the mRNA of both receptors is colocalized in both mouse and human dorsal root ganglion. Single-cell RNAseq of dorsal root ganglion from chronic constriction injury mice showed that the mRNA of both receptors (Cnr1 and Oprm1) is coexpressed across different neuron clusters. Myc-CB1R and FLAG-MOR were cotransfected into immortalized HEK-293T cells and were found to interact at a subcellular level. We also find that CB-13 (a peripherally restricted dual CB1R and cannabinoid receptor type 2 agonist) and DALDA (a peripherally restricted MOR agonist) both attenuate mechanical hypersensitivity in a murine model of neuropathic pain. Using isobolographic analysis, we demonstrate that when coadministered, these agents synergistically attenuate mechanical hypersensitivity. Importantly, combination dosing of these agents does not cause any detectable preferential behaviors or motor impairment. However, repeated dosing of these agents is associated with the development of tolerance to these drugs. Collectively, these findings suggest that leveraging synergistic pain inhibition between cannabinoid receptor and MOR agonists in peripheral sensory neurons may be worth examining in patients with neuropathic pain.

Cannabis and Cannabinoids in the Perioperative Period

Cannabis use is increasingly common, and with a growing number of jurisdictions implementing legalization frameworks, it is likely that providers will encounter more patients who use cannabis. Therefore, it is important for providers to understand the implications of cannabis use and practical considerations for the perioperative period. Cannabis affects multiple organ systems and may influence intraoperative anesthesia, as well as postoperative pain management. The effects of cannabis and key anesthetic considerations are reviewed here.

Alleviation of Pain, PAIN Interference, and Oxidative Stress by a Novel Combination of Hemp Oil, Calamari Oil, and Broccoli: A Randomized, Double-Blind, Placebo-Controlled Trial

Chronic pain is a critical health issue in the US that is routinely managed pharmacologically with diminishing results. The widespread misuse and abuse of prescription opioid pain medications have caused both healthcare providers and patients to seek alternative therapeutic options. Several dietary ingredients have been traditionally used for pain relief and are known to have potential analgesic properties. This double-blind, placebo-controlled randomized clinical trial aimed to test whether a novel combination of full spectrum hemp oil (phytocannabinoids), calamari oil (omega-3 fatty acids), and broccoli (glucosinolates) could reduce chronic pain and attenuate damage from oxidative stress in adults seeking chiropractic care. Participants (average age = 54.8 ± 13.6 years old) were randomly assigned to consume a whole-food, multi-ingredient supplement (n = 12, intervention and standard chiropractic care) or placebo (n = 13, mineral oil and standard chiropractic care) daily for 12 weeks. The subjects' self-reported perceived pain, pain interference, and reactive oxygen species (ROS) status in the peripheral blood mononuclear cells (PBMC) were quantified at baseline, mid-checkpoint, and postintervention. The intervention was positively associated with a 52% decrease in pain intensity and several parameters of pain interference, including quality of sleep. Decreases in the markers of oxidative stress were also observed in the participants from the intervention group (29.4% decrease in PMBC ROS). Our findings indicated that supplementation with a novel combination of hemp oil, calamari oil, and broccoli has the potential to manage chronic pain when combined with standard chiropractic care, as suggested by its effects on pain intensity and oxidative stress.

Alternative pain management via endocannabinoids in the time of the opioid epidemic: Peripheral neuromodulation and pharmacological interventions

The use of opioids in pain management is hampered by the emergence of analgesic tolerance, which leads to increased dosing and side effects, both of which have contributed to the opioid epidemic. One promising potential approach to limit opioid analgesic tolerance is activating the endocannabinoid system in the CNS, via activation of CB1 receptors in the descending pain inhibitory pathway. In this review, we first discuss preclinical and clinical evidence revealing the potential of pharmacological activation of CB1 receptors in modulating opioid tolerance, including activation by phytocannabinoids, synthetic CB1 receptor agonists, endocannabinoid degradation enzyme inhibitors, and recently discovered positive allosteric modulators of CB1 receptors. On the other hand, as non-pharmacological pain relief is advocated by the US-NIH to combat the opioid epidemic, we also discuss contributions of peripheral neuromodulation, involving the electrostimulation of peripheral nerves, in addressing chronic pain and opioid tolerance. The involvement of supraspinal endocannabinoid systems in peripheral neuromodulation-induced analgesia is also discussed. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

ASRA Pain Medicine consensus guidelines on the management of the perioperative patient on cannabis and cannabinoids

BACKGROUND

The past two decades have seen an increase in cannabis use due to both regulatory changes and an interest in potential therapeutic effects of the substance, yet many aspects of the substance and their health implications remain controversial or unclear.

METHODS

In November 2020, the American Society of Regional Anesthesia and Pain Medicine charged the Cannabis Working Group to develop guidelines for the perioperative use of cannabis. The Perioperative Use of Cannabis and Cannabinoids Guidelines Committee was charged with drafting responses to the nine key questions using a modified Delphi method with the overall goal of producing a document focused on the safe management of surgical patients using cannabinoids. A consensus recommendation required ≥75% agreement.

RESULTS

Nine questions were selected, with 100% consensus achieved on third-round voting. Topics addressed included perioperative screening, postponement of elective surgery, concomitant use of opioid and cannabis perioperatively, implications for parturients, adjustment in anesthetic and analgesics intraoperatively, postoperative monitoring, cannabis use disorder, and postoperative concerns. Surgical patients using cannabinoids are at potential increased risk for negative perioperative outcomes.

CONCLUSIONS

Specific clinical recommendations for perioperative management of cannabis and cannabinoids were successfully created.

Spinal cannabinoid receptor 2 activation alleviates neuropathic pain by regulating microglia and suppressing P2X7 receptor

Neuropathic pain (NP) is the chronic pain in patients resulting from injuries or diseases in the somatosensory nervous system. However, effective treatment remains limited to opioids. Currently, there is an urgent need to develop new specific pharmaceuticals with low abuse potentiality. Cannabinoid receptor 2 (CB2R) is one of the significant receptors in the endocannabinoid system. It is widely expressed in the central nervous system, especially enriched in glial cells, and plays an important role in the occurrence and development of inflammation in the nervous system. CB2R activation has a neuroprotective effect on nerve injury. In this study, we report increased and more reactive microglia (with larger cell body, shorter processes, and fewer endpoints) observed in the spinal dorsal horn of spared nerve injury (SNI) rats. Continuous intrathecal administration of CB2R agonist PM226 attenuated mechanical and cold hyperalgesia in rats and prevented the transition of microglia to the proinflammatory stage. Thus, microglia transitioned into the neuroprotective stage. Meanwhile, the proinflammatory factors TNF-α and iNOS decreased, and the levels of anti-inflammatory factors Arg-1 and IL-10 increased. The content of P2X7 receptors in the spinal dorsal horn of rats increases with time after SNI. After continuous intrathecal administration of PM226, the content of P2X7 protein decreases significantly. The administration of P2X7 inhibitor A-438079 alleviated the mechanical hyperalgesia of rats, reduced the number of microglia, and decreased the content of P2X7. These results indicate that P2X7 is involved in the neuroprotective effect caused by CB2R activation. In conclusion, this study provides new insights into the neuroprotective mechanism of CB2R activation.

Synergistic action between a synthetic cannabinoid compound and tramadol in neuropathic pain rats

In the present study the interaction of cannabinoid, PhAR-DBH-Me [(R, Z)-18-((1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)-18-oxooctadec-9-en-7-ylphenyl-acetate] and tramadol in two neuropathy models, as well as their possible toxic effects, was analyzed. The anti-allodynic effect of PhAR-DBH-Me, tramadol, or their combination, were evaluated in neuropathic rats. Furthermore, the effective dose 35 (as the 35 % of the anti allodynic effect) was calculated from the maximum effect of each drug. Moreover, the isobolographic analysis was performed to determine the type of interaction between the drugs. A plasma acute toxicity study was carried out to assess the hepatic, renal, and heart functions after an individual or combined administration of the drugs, as well as histology using the hematoxylin-eosin or Masson-trichome method. PhAR-DBH-Me, tramadol, and their combination produced an antiallodynic effect on spinal nerve ligation (SNL) and cisplatin-induced neuropathic pain in rats. Moreover, PhAR-DBH-Me and tramadol combination showed a synergistic interaction in neuropathic pain rats induced by SNL but not for cisplatin-induced neuropathy. On the other hand, changes in renal and hepatic functions were not observed. Likewise, analysis of liver, kidney and heart histology showed no alterations compared with controls. Results show that the combination of PhAR-DBH-Me and tramadol attenuates the allodynia in SNL rats; the acute toxicology analysis suggests that this combination could be considered safe in administered doses.

Cannabis, cannabinoids, and cannabis-based medicines: future research directions for analgesia

The use of cannabis spans thousands of years and encompasses almost all dimensions of the human experience, including consumption for recreational, religious, social, and medicinal purposes. Its use in the management of pain has been anecdotally described for millennia. However, an evidence base has only developed over the last 100 years, with an explosion in research occurring in the last 20-30 years, as more states in the USA as well as countries worldwide have legalized and encouraged its use in pain management. Pain remains one of the most common reasons for individuals deciding to use cannabis medicinally. However, cannabis remains illegal at the federal level in the USA and in most countries of the world, making it difficult to advance quality research on its efficacy for pain treatment. Nonetheless, new products derived both from the cannabis plant and the chemistry laboratory are being developed for use as analgesics. This review examines the current landscape of cannabinoids research and future research directions in the management of pain.

Effect of preoperative cannabis use on perioperative outcomes: a retrospective cohort study

INTRODUCTION

The reported use of cannabis within surgical population is increasing. Cannabis use is potentially associated with increased harms and varied effects on pain control. These have important implications to perioperative care.

METHODS

We conducted a retrospective cohort study comparing surgical patients reporting cannabis use preoperatively to control patients with no cannabis exposure, in a 1:2 ratio. To control for confounding, we used a propensity score-matched analysis to assess the adjusted association between cannabis use and study outcomes. Our primary outcome was a composite of (1) respiratory arrest or cardiac arrest, (2) intensive care admission, (3) stroke, (4) myocardial infarction and (5) mortality during this hospital stay. Secondarily, we assessed the effects on pain control, opioid usage, induction agent dose and nausea-vomiting.

RESULTS

Between January 2018 and March 2019, we captured 1818 patients consisting of cannabis users (606) and controls (1212). For propensity score-matched analyses, 524 cannabis patients were compared with 1152 control patients. No difference in the incidence of composite outcome was observed (OR 1.06, 95% CI 0.23 to 3.98). Although a higher incidence of arrhythmias (2.7% vs 1.6%) and decreased incidence of nausea-vomiting needing treatment (9.6% vs 12.6%) was observed with cannabis users vs controls, results were not statistically significant. No significant differences were observed with other secondary outcomes.

CONCLUSION

Our results do not demonstrate a convincing association between self-reported cannabis use and major surgical outcomes or pain management. Perioperative decisions should be made based on considerations of dose, duration, and indication.