“Nociception and motor coordination are critically governed by glycine receptor (GlyR) function at inhibitory synapses. Consequentially, GlyRs are attractive targets in the management of chronic pain and in the treatment of several neurological disorders. High-resolution mechanistic details of GlyR function and its modulation are just emerging.
While it has been known that cannabinoids such as Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent in marijuana, potentiate GlyR in the therapeutically relevant concentration range, the molecular mechanism underlying this effect is still not understood.
Here, we present Cryo-EM structures of full-length GlyR reconstituted into lipid nanodisc in complex with THC under varying concentrations of glycine. The GlyR-THC complexes are captured in multiple conformational states that reveal the basis for THC-mediated potentiation, manifested as different extents of opening at the level of the channel pore.
Taken together, these structural findings, combined with molecular dynamics simulations and functional analysis, provide insights into the potential THC binding site and the allosteric coupling to the channel pore.”
“Objectives: Considering that γ-terpinene (γ-TPN) is a monoterpene found in Cannabis oil, with high lipophilicity and limited pharmacokinetics, our objective was to evaluate whether its complexation in β-cyclodextrin (γ-TPN/β-CD) could improve its physicochemical properties and action on cancer pain, as well as verify the mechanisms of action involved.
Results: β-CD improved the physicochemical properties and prolonged the anti-hyperalgesic effect of γ-TPN. This compound also reduced the levels of IL-1β, TNF-α and iNOS in the tumour, and c-Fos protein in the spinal cord. In addition, it reduced Ca2+ current, presenting favourable chemical interactions with different voltage-dependent calcium channels.
Conclusion: These results indicate that the complexation of γ-TPN into β-CD increases its stability and time effect, reducing spinal neuroactivity and inflammation by blocking calcium channels.”
“Background: The psychoactive and non-psychoactive constituents of cannabis, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), synergistically reduce allodynia in various animal models of neuropathic pain. Unfortunately, THC-containing drugs also produce substantial side-effects when administered systemically. We examined the effectiveness of targeted spinal delivery of these cannabis constituents, alone and in combination.
Methods: The effect of acute intrathecal drug delivery on allodynia and common cannabinoid-like side-effects was examined in a mouse chronic constriction injury (CCI) model of neuropathic pain.
Results: intrathecal THC and CBD produced dose-dependent reductions in mechanical and cold allodynia. In a 1:1 combination, they synergistically reduced mechanical and cold allodynia, with a two-fold increase in potency compared to their predicted additive effect. Neither THC, CBD nor combination THC:CBD produced any cannabis-like side-effects at equivalent doses. The anti-allodynic effects of THC were abolished and partly reduced by cannabinoid CB1 and CB2 receptor antagonists AM281 and AM630, respectively. The anti-allodynic effects of CBD were partly reduced by AM630.
Conclusions: these findings indicate that intrathecal THC and CBD, individually and in combination, could provide a safe and effective treatment for nerve injury induced neuropathic pain.”
“The present findings indicate that intrathecal delivery of the phytocannabinoids THC and CBD reduces the mechanical and cold allodynia associated with a nerve injury induced model of neuropathic pain. Interestingly, THC and CBD acted synergistically to reduce allodynia, leading to a substantial increase in their anti-allodynic potency. In addition, both THC and CBD were devoid of the cannabis-like side-effects associated with the systemic delivery of THC-containing cannabinoids. These findings indicate that spinal delivery of the primary phytocannabinoids of the plant Cannabis sativa has potential in the treatment of chronic neuropathic pain.”
“Introduction: Medicinal cannabis is prescribed in Australia for patients with chronic refractory pain conditions. However, measures of safety and effectiveness of different cannabinoids are lacking. We designed an observational study to capture effectiveness, adverse events (AEs), and health-related quality of life (HRQoL) measures in patients prescribed an oral medicinal cannabis formulation at Cannabis Access Clinics through the Cannabis Access Clinics Observational study (CACOS).
Objectives: We aimed to evaluate effectiveness, reported AEs, and change in patient-reported outcomes in individuals prescribed a cannabinoid oil formulation for management of chronic pain.
Methods: A cross-sectional analysis was conducted on patients prescribed an oil formulation of Δ9-tetrahydrocannabinol and cannabidiol for pain symptoms of at least 3-month duration. Clinician-reported AEs were organized by system, organ, class, and frequency. Analysis of patient-reported responses to a questionnaire was conducted using published minimal clinically important differences to determine meaningful change in HRQoL over time.
Results: More than half (n = 91/151, 60.3%) of the participants experienced at least one AE during the observation period (mean 133 ± 116 days). No serious AEs were reported. Patient-reported pain impact scores were significantly reduced across the cohort (p = 0.034), and pain intensity scores verged on significance (p = 0.053). The majority of patients saw meaningful improvements in sleep (49.3%) and fatigue (35.6%).
Conclusion: This analysis presents real-world data collected as part of standard of care. More than one-third of patients benefited from oral medicinal cannabis, which is impactful given the refractory nature of their pain. Amelioration of the impact of pain confirms continued prescribing of this formulation and validates our observational methodology as a tool to determine the therapeutic potency of medicinal cannabinoids.”
“This is a clinically relevant finding considering that this patient cohort comprises refractory cases where relief has not been obtained with existing medications, including opioids, NSAIDs, and steroids.”
“Purpose: To assess the safety, dosing, and preventive effects of cannabidiol (CBD) on chemotherapy-induced peripheral neuropathy (CIPN) in patients receiving oxaliplatin- or paclitaxel-based chemotherapy.
Methods: Patients with cancer scheduled to undergo treatment with carboplatin and paclitaxel (Carbo-Tax) or capecitabine and oxaliplatin (CAPOX) received 150 mg CBD oil twice daily (300 mg/daily) for 8 days beginning 1 day before initiation of chemotherapy. Ten CIPN-specific patient-reported outcome (PRO) measures were captured at baseline and each day after the first cycle of chemotherapy for 8 days. Multi-frequency vibrometry (MF-V) was captured at baseline and day 4 ± 1 after initiation of chemotherapy. Controls were obtained from a similar patient cohort that did not receive CBD. Adverse events were captured using the CTCAE ver. 4.03.
Results: From March to December 2021, 54 patients were recruited. CBD-treated patients were significantly older (p = 0.013/0.037, CAPOX/Carbo-Tax) compared to controls. Patients receiving CBD and CAPOX or Carbo-Tax showed significantly lower (better) change in Z-scores in high-frequency MF-V (125 and 250 Hz) compared to controls. This difference was most pronounced for patients receiving Carbo-Tax (- 1.76, CI-95 = [- 2.52; – 1.02] at 250 Hz). CAPOX patients treated with CBD had significantly lower peak baseline-adjusted difference in three PRO items on cold sensitivity to touch, discomfort swallowing cold liquids, and throat discomfort (- 2.08, – 2.06, and – 1.81, CI-95 = [- 3.89; – 0.12], NRS 0-10). No significant differences in PRO items were found for patients receiving Carbo-Tax. Possible side effects included stomach pain (grades 1-2) for patients receiving CAPOX.
Conclusion: CBD attenuated early symptoms of CIPN with no major safety concerns. Long-term follow-up is ongoing. Results should be confirmed in a larger, randomized study.”
“Background: Chronic opioid therapy (COT) has been used to treat many chronic pain conditions even with poor evidence for its long-term effectiveness. Medical cannabis has emerged with certain pain-relieving properties, which has led to questions as to its’ potential application, especially in relation to its effect on opioid use.
Objectives: This study investigates a proposed clinical context in offering medical cannabis as a treatment for chronic pain for those already using chronic opioid therapy. It then details patients’ daily morphine milligram equivalent (MME) usage.
Study design: This single-center prospective study follows a group of patients trialing medical cannabis treatment for chronic pain that is already using COT in order to determine individual efficacy. Continued medical cannabis treatment was a decision made by the patient, after trialing medical cannabis, to either continue medical cannabis along with COT at a reduced daily MME, or to revert back to their previous COT regimen.
Setting: This study was performed at the Allegheny Health Network Institute for Pain Medicine in Pittsburgh, Pennsylvania. The state of Pennsylvania legalized medical cannabis in April of 2016, and it became available to patients in February of 2018 through medical dispensaries.
Methods: One hundred and fifteen patients met the inclusion criteria, with the majority of those excluded due to not being treated with COT. Of the 115 who chose to undergo a medical cannabis trial in addition to their COT, 75 chose to remain certified for medical cannabis as they had significant pain relief and subsequently weaned down on opioids. Additionally, of the 115 choosing to undergo a medical cannabis trial, 30 chose to be decertified due to ineffectiveness or side effects, and those were placed back on their COT regimen. The other 10 were not included for other denoted reasons. Compliance was monitored through urine drug screens (UDS).
Results: There was a 67.1% average decrease in daily MME/patient from 49.9 to 16.4 MME at the first follow-up. There was a 73.3% decrease in MME at second follow-up from 49.9 to 13.3 MME with an ANOVA analysis denoting a significant difference of P < 0.0001.
Limitations: The period of follow-up presented at this point includes their first 6 months of treatment with medical cannabis and COT concomitantly.
Conclusions: Presenting medical cannabis to chronic pain patients on COT should be done in the context of a patient choice between medical cannabis WITH decrement of COT or continued current dose of COT in order to maximize effectiveness in opioid reduction as well as to limit polypharmacy concerns regarding medical cannabis. Allowing for a temporary short-term period where patients may trial medical cannabis, while concomitantly gradually weaning their COT, is also essential in determining medical cannabis’ individual effectiveness for that patient’s specific type of chronic pain, which should serve to maximize long-term opioid reduction results and hence decrease opioid-related overdose deaths.”
“Background: Despite the widespread use and sales of cannabidiol (CBD) products in the United States, there is a paucity of literature to evaluate its effectiveness, safety, or ideal route of administration for postoperative pain.
Purpose: To evaluate the potential analgesic effects of buccally absorbed CBD in patients who have undergone arthroscopic rotator cuff repair (ARCR).
Study design: Randomized controlled trial; Level of evidence, 1.
Methods: This was a US Food and Drug Administration-sanctioned, multicenter, placebo-controlled, randomized, double-blinded trial conducted in patients undergoing ARCR. Patients aged from 18 to 75 years undergoing ARCR were prospectively enrolled and randomized to the control and experimental groups. The experimental group received an oral, buccally absorbed tablet containing 25 mg of CBD 3 times a day if <80 kg, or 50 mg of CBD 3 times a day if >80 kg, for 14 days postoperatively, while the control group received an identical placebo. Patients were followed up on days 1, 2, 7, and 14, and visual analog scale (VAS) for pain scores, opioid consumption, and satisfaction with pain control were recorded. Additionally, liver function tests were conducted on days 7 and 14 to assess safety, and nausea was monitored. P < .05 was considered to be statistically significant.
Results: Overall, 100 patients were recruited, with 1 patient being excluded, for a total of 99 patients. There were no significant differences in patient demographics between the 2 groups. On day 1, the VAS pain score was significantly lower in the CBD group than in the control group (4.4 ± 3.1 vs 5.7 ± 3.2, respectively; P = .04), although this difference was no longer present on day 2 (4.7 ± 2.8 vs 5.3 ± 2.6, respectively; P = .32). On both days 1 and 2, patient satisfaction with pain control was significantly higher in the CBD group than in the control group (day 1: 7.0 ± 3.0 vs 5.6 ± 3.7, respectively [P = .04]; day 2: 7.3 ± 2.5 vs 6.0 ± 3.3, respectively [P = .03]). The quantity of opioids consumed was low in both groups, and there were no statistically significant differences in opioid consumption (P > .05). On days 7 and 14, there were no statistically significant differences in VAS scores, opioid consumption, or patient satisfaction with pain control between the CBD and control groups (P > .05 for all). There were no significant differences in liver function test results postoperatively (P > .05).
Conclusion: Buccally absorbed CBD demonstrated an acceptable safety profile and showed significant promise in the reduction of pain in the immediate perioperative period after ARCR compared with the control. Further studies are currently ongoing to confirm dosing and effectiveness in other orthopaedic conditions.”
“Background: Cannabigerol (CBG) is a non-psychoactive phytocannabinoid produced by the plant Cannabis sativa with affinity to various receptors involved in nociception. As a result, CBG is marketed as an over-the-counter treatment for many forms of pain. However, there is very little research-based evidence for the efficacy of CBG as an anti-nociceptive agent.
Methods: To begin to fill this knowledge gap, we assessed the anti-nociceptive effects of CBG in C57BL/6 mice using three different models of pain; cisplatin-induced peripheral neuropathy, the formalin test, and the tail-flick assay.
Results: Using the von Frey test, we found that CBG attenuated mechanical hypersensitivity evoked by cisplatin-induced peripheral neuropathy in both male and female mice. Additionally, we observed that this CBG-induced reduction in mechanical hypersensitivity was attenuated by the α2 -adrenergic receptor antagonist atipamezole (3 mg/kg, i.p.) and the CB1 R antagonist, AM4113 (3 mg/kg, i.p.), and blocked by the CB2 R antagonist/inverse agonist, SR144528 (10 mg/kg, i.p.). We found that the TRPV1 antagonist, SB705498 (20 mg/kg, i.p.) was unable to prevent CBG actions. Furthermore, we show that CBG:CBD oil (10 mg/kg, i.p.) was more effective than pure CBG (10 mg/kg) at reducing mechanical hypersensitivity in neuropathic mice. Lastly, we show that pure CBG and CBG:CBD oil were ineffective at reducing nociception in other models of pain, including the formalin and tail flick assays.
Conclusions: Our findings support the role of CBG in alleviating mechanical hypersensitivity evoked by cisplatin-induced peripheral neuropathy, but highlight that these effects may be limited to specific types of pain.”
“Objective: To determine if a 2-day protocol measuring pharmacokinetic and pharmacodynamic characteristics can demonstrate drug-drug interactions when smoked cannabis is added to orally administered hydrocodone/acetaminophen combination products.
Case summary: A 51-year-old non-Hispanic white male with chronic pain diagnoses participated in a 2-day pilot protocol. The participant attended two 7-hour in-lab days where he received 10 blood draws each day and completed self-administered pain and anxiety surveys. For both days, the participant took his prescribed dose of hydrocodone/acetaminophen (1/2 tablet of 7.5 mg/325 mg combination product) with the addition of 1 smoked pre-rolled marijuana cigarette (labeled as 0.5 g; 22.17% Δ9-tetrahydrocannabinol; 0.12% cannabidiol) on Day 2. Blood specimens were analyzed using mass spectrometry to quantify the difference of plasma hydrocodone levels between Day 1 and Day 2.
Results: Compared to Day 1, lower levels of pain and anxiety were reported during Day 2 with the addition of cannabis to oral hydrocodone/acetaminophen. Day 2 pharmacokinetic analysis also revealed more rapid absorption and overall lower levels of hydrocodone in plasma.
Discussion: Lower hydrocodone plasma levels in Day 2 may indicate cannabis’s effect on metabolism and reduce the risk of opioid toxicity. The quicker absorption rate of hydrocodone could explain lower pain and anxiety scores reported on the second day.
Conclusion and relevance: A 2-day protocol was able to capture differences across time in pharmacokinetic and pharmacodynamic measurements. Larger studies can be designed to better characterize the potential drug-drug interaction of cannabis and opioids.”
“Pharmacological synergism is a current strategy for the treatment of pain. However, few studies have been explored to provide evidence of the possible synergism between a non-steroidal anti-inflammatory drug (NSAID) and a cannabinoid agonist, in order to establish which combinations might be effective to manage pain.
The aim of this study was to explore the synergism between ibuprofen (IBU) and the synthetic cannabinoid WIN 55,212-2 (WIN) to improve pain relief by analyzing the degree of participation of the CB1 and CB2 cannabinoid receptors in the possible antinociceptive synergism using an experimental model of pain in Wistar rats.
First, the effective dose thirty (ED30) of IBU (10, 40, 80, and 160 mg/kg, subcutaneous) and WIN (3, 10, and 30 µg/p, intraplantar) were evaluated in the formalin test. Then, the constant ratio method was used to calculate the doses of IBU and WIN to be administered in combination (COMB) to determine the possible synergism using the isobolographic method. The participation of the CB1 and CB2 receptors was explored in the presence of the antagonists AM281 and AM630, respectively.
The combination of these drugs produced a supra-additive response with an interaction index of 0.13. In addition, AM281 and AM630 antagonists reversed the synergistic effect in 45% and 76%, respectively, suggesting that both cannabinoid receptors are involved in this synergism, with peripheral receptors playing a relevant role.
In conclusion, the combination of IBU + WIN synergism is mainly mediated by the participation of the CB2 receptor, which can be a good option for the better management of pain relief.”
