3,3-Dibromoflavanone, a synthetic flavonoid derivative for pain management with antidepressant-like effects and fewer side effects than those of morphine in mice.

In the pursuit of new lead compounds with fewer side effects than opioids, the novel synthetic phytochemical core, 3,3-dibromoflavanone (3,3-DBF), has emerged as a promising candidate for pain management. Acute assays demonstrated dose-dependent central and peripheral antinociceptive activity of 3,3-DBF through the µ-opioid receptor. This study aimed to explore repeated administration effects of 3,3-DBF in mice and compare them with morphine. Mice were treated with 3,3-DBF (30 mg/kg), morphine (6 mg/kg), or vehicle for 10 days, alongside single-treatment groups. Unlike morphine, 3,3-DBF demonstrated antinociceptive effects in the hot plate test without inducing tolerance. Locomotor activity and motor coordination tests (evaluated through the inverted screen and rotarod tests) revealed no significant differences between the 3,3-DBF-treated and control groups. The gastrointestinal transit assay indicated that 3,3-DBF did not induce constipation, in contrast to morphine. Furthermore, withdrawal signs assessed with the Gellert-Holtzman scale were not comparable to morphine. Additionally, 3,3-DBF exhibited antidepressant-like activity, reducing immobility time in the forced swimming and tail suspension tests, akin to imipramine. In summary, 3,3-DBF demonstrated antinociceptive effects without inducing tolerance or dependence and exhibited antidepressant properties. These findings highlight the potential of 3,3-DBF as a promising therapeutic agent for pain management and its comorbidities, offering advantages over morphine by minimizing side effects.

Immune response and cytokine profiles in post-laminectomy pain syndrome: comparative analysis after treatment with intrathecal opioids, oral opioids, and non-opioid therapies.

INTRODUCTION: This study explores the interaction between cytokines, cell-mediated immunity (T cells, B cells, and NK cells), and prolonged morphine administration in chronic neuropathic pain patients without cancer-related issues. Despite evidence of opioid immunomodulation, few studies have compared these interactions. METHODS: In a cross-sectional and comparative study, 50 patients with chronic low back radicular pain ("Failed Back Surgery Syndrome") were categorized into intrathecal morphine infusion (IT group, n = 18), oral morphine (PO group, n = 17), and non-opioid treatment (NO group, n = 15). Various parameters, including plasma and cerebrospinal fluid (CSF) cytokine concentrations, lymphocyte immunophenotyping, opioid escalation indices, cumulative morphine dose, and treatment duration, were assessed. RESULTS: CSF IL-8 and IL-1ß concentrations exceeded plasma levels in all patients. No differences in T, B, and NK lymphocyte numbers were observed between morphine-treated and non-treated patients. Higher plasma IL-5 and GM-CSF concentrations were noted in IT and PO groups compared to NO. CSF IFNγ concentrations were higher in PO and NO than IT. Positive correlations included CD4 concentrations with opioid escalation indices, and negative correlations involved NK cell concentrations, CSF TNFα concentrations, and opioid escalation indices. Positive correlations were identified between certain cytokines and pain intensity in IT patients, and between NK cells and cumulative morphine dose. Negative correlations were observed between CSF IL-5 concentrations and pain intensity in IT and PO, and between opioid escalation indices and CSF cytokine concentrations in PO and IT. CONCLUSION: Associations between cytokines, cellular immunity, and prolonged morphine treatment, administered orally and intrathecally were identified.

Intravenous Methadone versus Intrathecal Morphine as Part of an Enhanced Recovery After Cardiac Surgery Protocol on Postoperative Pain and Outcomes: A Retrospective Cohort Study.

OBJECTIVES: Evaluate the effect of intravenous (IV) methadone versus intrathecal morphine (ITM) within an Enhanced Recovery After Cardiac Surgery (ERACS) pathway on postoperative pain and outcomes (length of hospital stay and postoperative complications) after cardiac surgery. DESIGN: Retrospective cohort study. SETTING: Two tertiary academic medical institutions within the same health system. PARTICIPANTS: Eligible 289 adult patients undergoing elective cardiac surgery with an enhanced recovery pathway from January 2020 through July 2021. INTERVENTIONS: Patients were administered ITM (0.25 mg) or IV methadone (0.1 mg/kg) if ITM was contraindicated. All patients were enrolled in an ERACS pathway using current Enhanced Recovery After Surgery society guidelines. MEASUREMENTS AND MAIN RESULTS: Primary outcome measures included postoperative pain scores and opioid consumption measured as oral morphine equivalents. We analyzed patient demographics, procedural factors, intraoperative medications, and outcomes. Adjusted linear mixed models were fit to analyze associations between intervention and pain outcomes. ITM was associated with decrease in pain scores on postoperative day 0 after adjusting for clinical variables (average marginal effect, 0.49; 95% confidence interval, 0.002-0.977; p = 0.049). No difference in opioid consumption could be demonstrated between groups after adjusting for postoperative day and other variables of interest. CONCLUSIONS: ITM when compared with IV methadone was associated with a decrease in pain scores without any difference in opioid consumption after elective cardiac surgery. Methadone can be considered as a safe and effective alternative to ITM for ERACS protocols. Future large prospective studies are needed to validate this finding and further improve analgesia and safety.

Baclofen prevents morphine rewarding effects and associated biochemical alterations in male and female mice.

Previous studies from our laboratory have shown sex differences in the behavioral, molecular, and neurochemical manifestations of morphine withdrawal and they were related to an increased sensitivity to morphine effects in males. In addition, we observed an interaction between the GABAergic and opioid systems that could also be sex-dependent. Baclofen, a GABAB receptor agonist, prevented the somatic expression and the molecular and neurochemical changes induced by morphine withdrawal syndrome in mice. On the contrary, little is known about baclofen effects in the rewarding properties of morphine in male and female mice. The present study aimed to explore the effect of baclofen (1, 2 and 3 mg/kg, i.p.) pretreatment in the rewarding effects induced by morphine (7 mg/kg, s.c.) and its effect on c-Fos and brain-derived neurotrophic factor (BDNF) expression induced by the rewarding properties of morphine in prepubertal male and female mice. Baclofen (2 mg/kg) pretreatment prevented the rewarding effects of morphine only in male mice, while baclofen (3 mg/kg) reduced these effects in both sexes. Moreover, the rewarding effects of morphine were associated with a decrease of BDNF and c-Fos expression cingulate cortex, nucleus accumbens shell, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) areas of the hippocampus only in male mice. In addition, baclofen pretreatment prevented these changes in BDNF, but not in c-Fos expression. In conclusion, our results show that GABAB receptors have a regulatory role in the rewarding effects of morphine that could be of interest for a potential future therapeutic application in opioid use disorders.

Oral Clonidine-Based Strategy to Reduce Opiate Use During Cooling for Neonatal Encephalopathy: An Observational Study.

OBJECTIVE: To determine whether an enteral, clonidine-based sedation strategy (CLON) during therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy would decrease opiate use while maintaining similar short-term safety and efficacy profiles to a morphine-based strategy (MOR). STUDY DESIGN: This was a single-center, observational study conducted at a level IV neonatal intensive care unit from January 1, 2017, to October 1, 2021. From April 13, 2020, to August 13, 2020, we transitioned from MOR to CLON. Thus, patients receiving TH for hypoxic-ischemic encephalopathy were grouped to MOR (before April 13, 2020) and CLON (after August 13, 2020). We calculated the total and rescue morphine milligram equivalent/kg (primary outcome) and frequency of hemodynamic changes (secondary outcome) for both groups. RESULTS: The MOR and CLON groups (74 and 25 neonates, respectively) had similar baseline characteristics and need for rescue sedative intravenous infusion (21.6% MOR and 20% CLON). Both morphine milligram equivalent/kg and need for rescue opiates (combined bolus and infusions) were greater in MOR than CLON (P < .001). As days in TH advanced, a lower percentage of patients receiving CLON needed rescue opiates (92% on day 1 to 68% on day 3). Patients receiving MOR received a greater cumulative dose of dopamine and more frequently required a second inotrope and hydrocortisone for hypotension. MOR had a lower respiratory rate during TH (P = .01 vs CLON). CONCLUSIONS: Our CLON protocol is noninferior to MOR, maintaining perceived effectiveness and hemodynamic safety, with an apparently reduced need for opiates and inotropes.

Pronociceptive role of spinal Cav2.3 (R-type) calcium channels in a mouse model of postoperative pain.

BACKGROUND: More than 80% of patients may experience acute pain after a surgical procedure, and this is often refractory to pharmacological intervention. The identification of new targets to treat postoperative pain is necessary. There is an association of polymorphisms in the Cav2.3 gene with postoperative pain and opioid consumption. Our study aimed to identify Cav2.3 as a potential target to treat postoperative pain and to reduce opioid-related side effects. EXPERIMENTAL APPROACH: A plantar incision model was established in adult male and female C57BL/6 mice. Cav2.3 expression was detected by qPCR and suppressed by siRNA treatment. The antinociceptive efficacy and safety of a Cav2.3 blocker-alone or together with morphine-was also assessed after surgery. KEY RESULTS: Paw incision in female and male mice caused acute nociception and increased Cav2.3 mRNA expression in the spinal cord but not in the incised tissue. Intrathecal treatment with siRNA against Cav2.3, but not with a scrambled siRNA, prevented the development of surgery-induced nociception in both male and female mice, with female mice experiencing long-lasting effects. High doses of i.t. SNX-482, a Cav2.3 channel blocker, or morphine injected alone, reversed postoperative nociception but also induced side effects. A combination of lower doses of morphine and SNX-482 mediated a long-lasting reversal of postsurgical pain in female and male mice. CONCLUSION: Our results demonstrate that Cav2.3 has a pronociceptive role in the induction of postoperative pain, indicating that it is a potential target for the development of therapeutic approaches for the treatment of postoperative pain.

Comparison of analgesic efficacy of tramadol, morphine and methadone in cats undergoing ovariohysterectomy.

OBJECTIVES: The aim of this study was to compare the analgesic efficacy and the effect on physiological variables and behavior of the use of tramadol, methadone and morphine as preoperative analgesia in healthy cats undergoing elective ovariohysterectomy. METHODS: Cats undergoing ovariohysterectomy were randomly assigned to receive one of the following premedication treatments intramuscularly: methadone (0.2 mg/kg; n = 10); morphine (0.2 mg/kg; n = 10); or tramadol (3 mg/kg; n = 10). Induction of anesthesia was done with propofol, and maintenance of anesthesia was done with isoflurane. Intraoperative heart rate, arterial blood pressure, respiratory rate, end-tidal isoflurane concentration and frequency of rescue analgesia (fentanyl 2.5 µg/kg) were compared between groups. Postoperative analgesia was assessed using the UNESP-Botucatu Multidimensional Composite Pain Scale, and perioperative serum glucose, cortisol concentrations and postoperative rescue analgesia were evaluated. RESULTS: Intraoperative rescue analgesia was required in 76.5% of cats at some time during surgery, and 27% of cats required postoperative rescue analgesia up to 6 h after extubation. There were no significant differences between groups with respect to intraoperative and postoperative rescue analgesia, pain scale scores and end-tidal isoflurane concentrations. In the immediate postoperative period, after extubation, most of the patients presented with hypothermia; however, 1-6 h postoperatively, hyperthermia was observed in most of the patients, and was most common in the tramadol group. CONCLUSIONS AND CLINICAL RELEVANCE: Under the conditions of this study, methadone, morphine and tramadol produced satisfactory postoperative analgesia in most of the cats undergoing ovariohysterectomy, and the effects lasted up to 6 h postoperatively. Intraoperative analgesia was not sufficient in most cases. Significant cardiovascular or respiratory effects contraindicating the use of these drugs were not found. Postanesthetic hyperthermia occurred with all opioids studied and was more frequent in the tramadol group.

The Inhibitory Effect of NSAIDs and Opioids on Spinal Fusion: An Animal Model.

STUDY DESIGN: Translational research. OBJECTIVE: To evaluate the relative effects of NSAIDs, opioids, and a combination of the two on spinal fusion inhibition in a rodent model. SUMMARY OF BACKGROUND DATA: Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are common postoperative analgesic agents. Since NSAIDs inhibit the cyclooxygenase (COX) pathway, they are seldom prescribed following spinal fusion. Opioids may be given instead, but recent evidence suggests opioids also adversely affect spinal fusion quality and success. METHODS: Eighty male Sprague-Dawley rats underwent L4-5 posterior lumbar fusion and were given one of the following analgesia regimens: saline, morphine (6 mg/kg), ketorolac (4 mg/kg), or morphine (3 mg/kg) and ketorolac (2 mg/kg). Serum samples were drawn to evaluate systemic pro-osteoblastic cytokines and vascular endothelial growth factor-A (VEGF-A) levels, which were measured through enzyme-linked immunosorbent assays (ELISA). After six weeks, the rats were sacrificed, and the operated spinal segments underwent manual palpation, microCT, and histologic analysis. RESULTS: Manual palpation scores were significantly diminished in the opioid, NSAID, and multimodal groups when compared with control ( P <0.001). MicroCT fusion scores ( P <0.001) and fusion rates (control: 75% vs . NSAID: 35% vs . opioid: 0% vs . combination: 15%, P <0.001) were significantly diminished in the treatment groups. The bone volume (BV) to tissue volume (TV) ratio (BV/TV) ( P <0.001) and bone mineral density (BMD) ( P <0.001) were all lower in the treatment groups, with the opioid and combined groups having the lowest BMD. Although statistically insignificant ( P <0.09), the concentration of VEGF-A was greater in the control group compared with opioids, NSAIDs, and the combined group. CONCLUSION: Opioids and NSAIDs, both independently and combined, inhibited spinal fusion and caused inferior bony callus. Administration of opioids resulted in the lowest rate of spinal fusion. We propose this may be due to the inhibition of VEGF-A, which limits angiogenesis to the burgeoning fusion mass.

Effectiveness of epidural morphine for the treatment of cancer pain in patients with gastrointestinal neoplasm-a systematic review.

One-third of cancer pain patients do not experience adequate pain relief using analgesic ladder by the World Health Organization. Interventional procedures, such as epidural morphine, have been considered. This study aimed to review the literature comparing the effects of epidural administration of morphine with the oral route. This systematic review included randomized controlled trials (RCTs) conducted with patients with gastrointestinal neoplasm. A search was conducted on PubMed, EMBASE, Web of Science, Scopus, Cochrane Library, and CINAHL databases to identify studies published up to May 2023. The retrieved study was evaluated using the Risk of Bias 2 (RoB 2) tool and qualitatively synthesized. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach (Prospero: CRD42021264728). Only one RCT, a crossover trial, was included in this systematic review. The study was conducted with ten participants (one withdrawal) and reported a statistically significant difference between both subcutaneous and epidural morphine solutions and oral morphine. The adverse events were not described. The included study presents some concerns of bias and low certainty of evidence on the effectiveness and security of epidural morphine administration. The available literature does not suffice to elucidate whether morphine administration via the epidural route is more effective than other routes. Further RCTs are necessary to improve the level of evidence on the effectiveness and risk-benefit of epidural morphine in the management of cancer pain in gastrointestinal neoplasm patients.

Amelioration of morphine withdrawal syndrome by systemic and intranasal administration of mesenchymal stem cell-derived secretome in preclinical models of morphine dependence.

BACKGROUND: Morphine is an opiate commonly used in the treatment of moderate to severe pain. However, prolonged administration can lead to physical dependence and strong withdrawal symptoms upon cessation of morphine use. These symptoms can include anxiety, irritability, increased heart rate, and muscle cramps, which strongly promote morphine use relapse. The morphine-induced increases in neuroinflammation, brain oxidative stress, and alteration of glutamate levels in the hippocampus and nucleus accumbens have been associated with morphine dependence and a higher severity of withdrawal symptoms. Due to its rich content in potent anti-inflammatory and antioxidant factors, secretome derived from human mesenchymal stem cells (hMSCs) is proposed as a preclinical therapeutic tool for the treatment of this complex neurological condition associated with neuroinflammation and brain oxidative stress. METHODS: Two animal models of morphine dependence were used to evaluate the therapeutic efficacy of hMSC-derived secretome in reducing morphine withdrawal signs. In the first model, rats were implanted subcutaneously with mini-pumps which released morphine at a concentration of 10 mg/kg/day for seven days. Three days after pump implantation, animals were treated with a simultaneous intravenous and intranasal administration of hMSC-derived secretome or vehicle, and withdrawal signs were precipitated on day seven by i.p. naloxone administration. In this model, brain alterations associated with withdrawal were also analyzed before withdrawal precipitation. In the second animal model, rats voluntarily consuming morphine for three weeks were intravenously and intranasally treated with hMSC-derived secretome or vehicle, and withdrawal signs were induced by morphine deprivation. RESULTS: In both animal models secretome administration induced a significant reduction of withdrawal signs, as shown by a reduction in a combined withdrawal score. Secretome administration also promoted a reduction in morphine-induced neuroinflammation in the hippocampus and nucleus accumbens, while no changes were observed in extracellular glutamate levels in the nucleus accumbens. CONCLUSION: Data presented from two animal models of morphine dependence suggest that administration of secretome derived from hMSCs reduces the development of opioid withdrawal signs, which correlates with a reduction in neuroinflammation in the hippocampus and nucleus accumbens.

Cost-effectiveness analysis of epidural morphine/ropivacaine treatment in patients with cancer pain.

BACKGROUND: Cancer pain is one of the main causes of human suffering, which can generate disabilities and compromise quality of life, giving rise to several psychosocial and economic consequences. AIMS: This quantitative study sought to perform a cost-effectiveness pharmacoeconomic analysis to assess the impact of implanting epidural morphine associated with ropivacaine treatment in gastrointestinal cancer patients with pain that is difficult clinical control, compared with conventional oral treatment. MATERIALS AND METHODS: The study population consisted of 24 patients with gastrointestinal neoplasia who underwent treatment for cancer pain that was difficult to clinically control. 12 patients each were recruited into the control and intervention groups, respectively. While patients in the control group were administered drug treatment orally, patients in the intervention group underwent a surgical procedure for subcutaneous implantation of a catheter that allowed epidural administration of morphine and ropivacaine. For pain assessment, the Visual Analogue Scale was applied. Data analysis had a descriptive character of costs, taking into account the costs for the year 2021. The study perspective was the Brazilian public healthcare provider, referred to as the Unified Health System (Sistema Único de-SUS in Portuguese). Costs were computed over the time horizon corresponding to the duration of treatment, from the first medical consultation (when the treatment was defined) to the end (end of treatment, disease progression, or death). Treatment duration was divided into three phases (first 60 days, support with palliative care, and end-of-life care). To assess the robustness of the economic analysis, sensitivity analyses were performed, considering the effectiveness of pain reduction on the Visual Analogue Scale, and a comparison of results using the median prices of pharmaceutical components used in the study. RESULTS: The mean age of patients was 59.3 years. The results from the cost-effectiveness analysis showed the epidural morphine/ropivacaine treatment to be more effective with regard to pain reduction on the pain scale, particularly for end-of-life care, when compared to the conventional oral treatment, however, at a significantly higher cost. DISCUSSION: From the accomplishment of this research, it was observed that the application of the pain assessment scale is a way to better interpret and understand the patient's pain, facilitating care planning and decision-making by health professionals, as well as monitoring the effectiveness of the proposed new treatment. CONCLUSION: To present a better cost-effectiveness ratio, a reduction in the cost of the new epidural technology or an increase in the value of the existing oral intervention would be required. However, the latter is not feasible and unlikely to occur. A value judgement to decide whether the incremental benefit associated with the use of the new intervention is worth the extra cost will have to be made by the healthcare provider. Interventions that can relieve cancer pain symptoms should be investigated continuously, in search of evidence to support clinical practice and promote better quality of life for patients.

Chronic Voluntary Morphine Intake Is Associated with Changes in Brain Structures Involved in Drug Dependence in a Rat Model of Polydrug Use.

Chronic opioid intake leads to several brain changes involved in the development of dependence, whereby an early hedonistic effect (liking) extends to the need to self-administer the drug (wanting), the latter being mostly a prefrontal-striatal function. The development of animal models for voluntary oral opioid intake represents an important tool for identifying the cellular and molecular alterations induced by chronic opioid use. Studies mainly in humans have shown that polydrug use and drug dependence are shared across various substances. We hypothesize that an animal bred for its alcohol preference would develop opioid dependence and further that this would be associated with the overt cortical abnormalities clinically described for opioid addicts. We show that Wistar-derived outbred UChB rats selected for their high alcohol preference additionally develop: (i) a preference for oral ingestion of morphine over water, resulting in morphine intake of 15 mg/kg/day; (ii) marked opioid dependence, as evidenced by the generation of strong withdrawal signs upon naloxone administration; (iii) prefrontal cortex alterations known to be associated with the loss of control over drug intake, namely, demyelination, axonal degeneration, and a reduction in glutamate transporter GLT-1 levels; and (iv) glial striatal neuroinflammation and brain oxidative stress, as previously reported for chronic alcohol and chronic nicotine use. These findings underline the relevance of polydrug animal models and their potential in the study of the wide spectrum of brain alterations induced by chronic morphine intake. This study should be valuable for future evaluations of therapeutic approaches for this devastating condition.

The effectiveness of erector spina plane, quadratus lumborum blocks, and intrathecal morphine for analgesia after cesarean: a randomized study.

OBJECTIVE: This prospective randomized study was conducted at Ataturk University Medical Faculty Hospital, Department of Anesthesia and Reanimation, from June 2022 to May 2023. The aim of this study was to compare the effectiveness of ultrasound-guided erector spinae plane block, quadratus lumborum block, and intrathecal morphine to decrease postoperative pain after cesarean section. METHODS: Sixty-term pregnant women who were scheduled for elective cesarean sections with spinal anesthesia were included. Patients were randomly divided into three groups (n=20 for each group): Group 1: Patients were administered intrathecal morphine during spinal anesthesia; Group 2: Patients performed bilateral erector spinae plane block postoperatively; and Group 3: Patients performed bilateral quadratus lumborum block postoperatively. In the postpartum care unit, patients received intravenous Patient-Controlled Analgesia. The Patient-Controlled Analgesia devices were set to administer an intravenous bolus of 25 µg fentanyl, with a lockout interval of 10 min. Opioid consumption and maximum pain score in the 24 postoperative hours were recorded. RESULTS: Patients in Group 1 had a longer time to first analgesic requirement compared to Group 2 (p=0.017). Opioid consumption and resting and moving visual analog score scores in the first 24 h postoperatively were similar between groups. CONCLUSION: All three methods, including intrathecal morphine, erector spinae plane block, and quadratus lumborum block, are efficacious and comparable in providing postoperative analgesia after cesarean under spinal anesthesia.

Shift in hospital opioid use during the COVID-19 pandemic in Brazil: a time-series analysis of one million prescriptions.

The pronounced change in the profile of hospitalized patients during COVID-19 and the severe respiratory component of this disease, with a great need for mechanical ventilation, led to changes in the consumption pattern of some medicines and supplies. This time-series study analyzed the in-hospital consumption of opioids during the COVID-19 pandemic in 24 Brazilian hospitals compared to the pre-pandemic period. Data included 711,883 adult patients who had opioids prescribed. In 2020, the mean consumption was significantly higher compared to 2019 for parenteral fentanyl, enteral methadone, and parenteral methadone. It was significantly lower for parenteral morphine parenteral sufentanil, and parenteral tramadol. For remifentanil, it did not differ. The number of patients in 2020 was lower but the mean consumption was higher for fentanyl, parenteral methadone, and remifentanil. It was lower for enteral methadone and parenteral sufentanil. The consumption of parenteral morphine and parenteral tramadol was stable. There was a relevant increase in hospital consumption of some potent opioids during the COVID-19 pandemic in Brazil. These results reinforce the concern about epidemiological surveillance of opioid use after periods of increased hospital use since in-hospital consumption can be the gateway to the misuse or other than the prescribed use of opioids after discharge.

Exploring the therapeutic potential of an antinociceptive and anti-inflammatory peptide from wasp venom.

Animal venoms are rich sources of neuroactive compounds, including anti-inflammatory, antiepileptic, and antinociceptive molecules. Our study identified a protonectin peptide from the wasp Parachartergus fraternus' venom using mass spectrometry and cDNA library construction. Using this peptide as a template, we designed a new peptide, protonectin-F, which exhibited higher antinociceptive activity and less motor impairment compared to protonectin. In drug interaction experiments with naloxone and AM251, Protonectin-F's activity was decreased by opioid and cannabinoid antagonism, two critical antinociception pathways. Further experiments revealed that this effect is most likely not induced by direct action on receptors but by activation of the descending pain control pathway. We noted that protonectin-F induced less tolerance in mice after repeated administration than morphine. Protonectin-F was also able to decrease TNF-α production in vitro and modulate the inflammatory response, which can further contribute to its antinociceptive activity. These findings suggest that protonectin-F may be a potential molecule for developing drugs to treat pain disorders with fewer adverse effects. Our results reinforce the biotechnological importance of animal venom for developing new molecules of clinical interest.

Cannabidiol attenuates the expression of conditioned place aversion induced by naloxone-precipitated morphine withdrawal through the activation of 5-HT1A receptors.

The misuse of and addiction to opioids are serious public health problems in some countries, such as the USA. Drug addiction is a chronic and relapsing medical condition that involves motivational and memory-related processes due to the strong associations between drugs and consuming-related stimuli. These stimuli usually trigger continuous and compulsive use and are associated with relapses after periods of withdrawal. Several factors contribute to relapse, including withdrawal-induced mood changes. Therefore, drugs attenuating withdrawal-induced affective alterations could be useful alternative treatments for relapse prevention. Cannabidiol (CBD), a non-psychotomimetic component from the Cannabis sativa plant, has anti-anxiety and anti-stress properties and has been investigated as an alternative for the treatment of several mental disorders, including drug addiction. Here, we evaluated if CBD administered 30 min prior to test for a conditioned place aversion (CPA) would attenuate the aversion induced by morphine withdrawal precipitated by the opioid receptor antagonist naloxone in male C57BL/6 mice. We also investigated if this effect involves the activation of 5-HT1A receptors, a mechanism previously associated with CBD anti-aversive effects. As expected, morphine-treated mice spent less time exploring the compartment paired with the naloxone-induced withdrawal, indicating a CPA induced by naloxone-precipitated morphine withdrawal. This effect was not observed in animals treated with CBD, at 30 and 60 mg/kg, prior to the CPA test, indicating that CBD attenuated the expression of CPA induced by naloxone-precipitated morphine withdrawal. Pretreatment with the 5-HT1A receptor antagonist WAY100635 (0.3 mg/kg) blocked CBD effects. Our findings suggest that CBD may reduce the expression of a previously established conditioned aversion induced by morphine withdrawal by a mechanism involving the activation of 5-HT1A receptors. Thus, CBD may be a therapeutic alternative for preventing relapse to opioid addiction by decreasing withdrawal-induced negative affective changes.

Is Acetaminophen Beneficial in Patients With Cancer Pain Who are on Strong Opioids? A Randomized Controlled Trial.

CONTEXT: Pain is common among cancer patients. The evidence recommends using strong opioids in moderate to severe cancer pain. No conclusive evidence supports the effectiveness of adding acetaminophen to patients with cancer pain who are already using this regime. OBJECTIVES: To assess the analgesic efficacy of acetaminophen in hospitalized cancer patients with moderate to severe pain receiving strong opioids. METHODS: In this randomized blinded clinical trial, hospitalized cancer patients with moderate or severe acute pain managed with strong opioids were randomized to acetaminophen or placebo. The primary outcome was pain intensity difference between baseline and 48 hours using the Visual Numeric Rating Scales (VNRS). Secondary outcomes included change in morphine equivalent daily dose (MEDD), and patients' perception of improved pain control. RESULTS: Among 112 randomized patients, 56 patients received placebo, 56 acetaminophen. Mean (standard deviation [SD]) decrease in pain intensity (VNRS) at 48 hours were 2.7 (2.5) and 2.3 (2.3), respectively (95% Confidence Interval (CI) [-0.49; 1.32]; P = 0.37). Mean (SD) change in MEDD was 13.9 (33.0) mg/day and 22.4 (57.7), respectively (95% CI [-9.24; 26.1]; P = 0.35). The proportion of patients perceiving pain control improvement after 48 hours was 82% in the placebo and 80% in the acetaminophen arms (P = 0.81). CONCLUSION: Among patients with cancer pain on strong opioid regime, acetaminophen may not improve pain control, or decrease total opioid use. These results add to the current evidence available suggesting not to use acetaminophen as an adjuvant for advanced cancer patients with moderate to severe cancer pain who are on strong opioids.

Morphine and dopamine: Low dose apomorphine can prevent both the induction and expression of morphine locomotor sensitization and conditioning.

The disinhibition of dopamine neurons in the VTA by morphine is considered an important contributor to the reward potency of morphine. In this report, three experiments were conducted in which a low dose of apomorphine (0.05 mg/kg) was used as a pretreatment to reduce dopamine activity. Locomotor hyperactivity was used as the behavioral response to morphine (10.0 mg/kg). In the first experiment, five treatments with morphine induced the development of locomotor and conditioned hyperactivity that were prevented by apomorphine given 10 min prior to morphine. Apomorphine before either vehicle or morphine induced equivalent reductions in locomotion. In the second experiment, the apomorphine pretreatment was initiated after induction of a conditioned hyperactivity and apomorphine prevented the expression of the conditioning. To assess the effects of apomorphine on VTA and the nucleus accumbens, ERK measurements were carried out after the induction of locomotor and conditioned hyperactivity. Increased ERK activation was found and these effects were prevented by the apomorphine in both experiments. A third experiment was conducted to assess the effects of acute morphine on ERK before locomotor stimulation was induced by morphine. Acute morphine did not increase locomotion, but a robust ERK response was produced indicating that the morphine-induced ERK activation was not secondary to locomotor stimulation. ERK activation was again prevented by the apomorphine pretreatment. We suggest that contiguity between the ongoing behavioral activity and the morphine activation of the dopamine reward system incentivizes and potentiates the ongoing behavior generating equivalent behavioral sensitization and conditioned effects.

Effect of magnesium sulfate with ketamine infusions on intraoperative and postoperative analgesia in cancer breast surgeries: a randomized double-blind trial

Abstract Background Opioids are the cornerstone in managing postoperative pain; however, they have many side effects. Ketamine and Magnesium (Mg) are NMDA receptor antagonists used as adjuvant analgesics to decrease postoperative opioid consumption. Objective We assumed that adding Mg to ketamine infusion can improve the intraoperative and postoperative analgesic efficacy of ketamine infusion alone in cancer breast surgeries. Methods Ninety patients aged between 18 and 65 years and undergoing elective cancer breast surgery were included in this prospective randomized, double-blind study. Group K received ketamine 0.5 mg.kg-1 bolus then 0.12 mg.kg-1.h-1 infusion for the first 24 hours postoperatively. Group KM: received ketamine 0.5 mg.kg-1 and Mg sulfate 50 mg.kg-1, then ketamine 0.12 mg.kg-1.h-1 and Mg sulfate 8 mg.kg-1.h-1 infusions for the first 24 hours postoperative. The primary outcome was the morphine consumption in the first 24 hours postoperative, while the secondary outcomes were: intraoperative fentanyl consumption, NRS, side effects, and chronic postoperative pain. Results Group KM had less postoperative opioid consumption (14.12 ± 5.11 mg) than Group K (19.43 ± 6.8 mg). Also, Group KM had less intraoperative fentanyl consumption. Both groups were similar in postoperative NRS scores, the incidence of side effects related to opioids, and chronic neuropathic pain. Conclusion Adding Mg to ketamine infusion can safely improve intraoperative and postoperative analgesia with opioid-sparing effect in cancer breast surgery.