Preparation and Evaluation of the In situ Gel-forming Chitosan Hydrogels for Nasal Delivery of Morphine in a Single Unit dose in Rats to Enhance the Analgesic Responses

INTRODUCTION

In this study, an in situ gel-forming chitosan hydrogel was prepared with the use of glutamate salt of chitosan (Ch-Ga), β-glycerophosphate (Gp), and morphine (Mor). The paper is focused on in vitro physicochemical properties and in-vivo analgesic effects of the prepared chitosan hydrogel.

METHOD

The thermosensitive properties of prepared chitosan hydrogel were evaluated during the different temperatures and times. The physicochemical properties of chitosan hydrogel were investigated by infrared (IR) spectroscopy and X-ray diffraction analysis (XRD). Also, its cell cytotoxicity effects were evaluated in murine NIH/3T3 normal cells. Subsequently, the distribution of chitosan hydrogel in the nasal cavity of rats and its analgesic responses were evaluated. The prepared chitosan hydrogel showed that it could be gelled at the temperature of 34 °C before leaving the nose in the shortest possible time of 30 s.

RESULT

The analgesic responses of the intranasal (IN) injection of chitosan hydrogel (IN-chitosan hydrogel, 10 mg Mor/kg) in a single unit dose in rat relative to the placebo and intranasal or intraperitoneal (IP) injection of free morphine solution (IN-Free Mor or IP-Free Mor, 10 mg Mor/kg) via the hot plate test, reveal that the IN-chitosan hydrogel could induce fast analgesic effects of morphine with maximum possible effect (MPE) of 93% after 5 min compare to the IN-Free Mor and IP-Free Mor with MPE of 80% after 15 min and 66% after 30 min, respectively. Also, prolonged analgesic effects with MPE of 78 % after 6 h of injection were only seen in the IN-chitosan hydrogel injected group. The obtained fluorescent images of rat's brain injected with IN-chitosan hydrogel containing doxorubicine (Dox) as a fluorescent agent showed that the mucosal adhesive and absorption enhancer properties of IN-chitosan hydrogel resulting in longer presence of them in the nasal cavity of rats followed by more absorption of Dox from the blood vessels of olfactory bulbs with a 74% color intensity compared to the IN-Free Mor and IN-Free Dox with 15%.

CONCLUSION

These data reveal that the IN-chitosan hydrogel could induce fast and prolonged analgesic effects of morphine compare to the IN/IP-Free Mor, which could be considered as an in situ gel-forming thermosensitive chitosan hydrogel for nasal delivery of wide ranges of therapeutic agents.

A Randomized Control Study to Assess the Efficacy of Intrathecal Morphine in Patients on Patient-Controlled Analgesia Pump With Morphine for Postoperative Pain Relief After Elective Laparotomy

Introduction Laparotomy is associated with significant prolonged postoperative pain, which can cause an adverse neuroendocrine stress response. Intrathecal morphine (ITM) retains an important place in pain management after major laparotomy since it is easier to administer and has a relatively lesser possibility of failure and technical difficulty. Aim The study aims to compare the effect of the administration of ITM with intravenous (IV) morphine administered by a patient-controlled analgesia (PCA) pump on postoperative analgesia after elective laparotomy. The primary objective was to compare total morphine consumption while secondary objectives were to compare pain assessed by the visual analog scale (VAS) and adverse reactions to opioids. Methods Sixty patients who underwent elective laparotomy were enrolled in this study. Thirty patients were enrolled in the study group (ITM+PCA) where ITM (200 mcg) was administered before laparotomy and intravenous morphine was initiated with PCA postoperatively. In the control group, only intravenous morphine was given with PCA postoperatively for pain relief. Parameters in both groups were compared, where estimation of cumulative morphine dose was the primary outcome and pain as assessed by VAS and side effects of opioids were the secondary outcomes. Results Patients in the ITM (ITM+PCA) group required less morphine (6.6 ± 2.96 vs. 24.77 ± 6.79 mg of morphine, p < 0.001) compared to patients on PCA. There was no statistically significant difference in VAS score and adverse effects between both groups. Conclusion Preoperative ITM can be used as an effective and safe modality for alleviating immediate postoperative pain following laparotomy.

Protective Effect of Baclofen on Ovarian Cystogenesis and Morphine-Induced Lipid Profile Change in Female Rats

Introduction

Morphine induces ovarian cysts that cause obesity and disrupt sex hormone secretion. Baclofen, a gamma-aminobutyric acid receptor agonist, can help regulate sex hormones and reduce harmful blood lipids by protecting against morphine-induced gamma-aminobutyric acid inhibition. We investigated the prophylactic effect of baclofen in rats receiving morphine by comparing with the untreated groups.

Materials and Methods

Forty eight female Wistar rats were randomly divided into several groups, including control (saline 1 mL/kg, i.p.), morphine (5 mg/kg, i.p.), baclofen (10, 20, and 30 mg/kg, i.p.), and baclofen (10, 20, and 30 mg/kg) before morphine (5 mg/kg). Twenty four hours after the treatment, blood and serum samples were taken to check the levels of gonadotropins (LH & FSH) and lipid profile. The ovaries and uterus were also studied, and a proinflammatory nitric oxide (NO) diagnostic test was completed. The results were analyzed using analysis of variance (α = 0.05).

Results

In comparison with the control group, the levels of LH and not FSH decreased in the morphine group and the number of ovarian cysts was more in the morphine group. These problems were not observed in the group of baclofen alone and baclofen + morphine. However, the triglyceride level increased slightly in the baclofen 30 mg/kg + morphine group. But the LDL level somewhat decreased. The proinflammatory NO system did not show significant activation in the ovary and uterus, except for the baclofen 10 mg/kg + baclofen group.

Conclusion

Morphine can cause ovarian cysts by lowering LH but baclofen prophylaxis can protect reproductive properties by adapting major metabolic changes.

A Novel Multimodal Postoperative Pain Protocol for 1- to 2-Level Open Lumbar Fusions: A Retrospective Cohort Study

BACKGROUND

There has been increased interest in exploring methods to reduce postoperative pain without opioid medications. In 2015, a multimodal analgesia protocol was used involving the perioperative use of celecoxib, gabapentin, intravenous acetaminophen, lidocaine, and liposomal bupivacaine. Overall, the goal was to reduce the utilization of scheduled opioids in favor of nonopioid pain management.

METHODS

The results of a consecutive series of 1- to 2-level open primary lumbar fusions were compared to a cohort of patients after the implementation the perioperative multimodal pain management protocol. Primary endpoints included patient-reported pain scores and secondary endpoints included length of stay.

RESULTS

There were 87 patients in the preprotocol cohort and 184 in the protocol cohort. Comparing protocol and preprotocol patients, there were no significant differences in patient demographics. There was significantly average lower pain in the protocol group on postoperative day (POD) 1 (4.50 vs 5.00, P < 0.02) and POD2 (4.42 vs 5.50, P < 0.03). There was a lower pain score on POD0 (4.80 vs 5.00), but it was only clinically significant. There was a correlation between pain and duration of surgery in the preprotocol patients (POD0 R = 0.23, POD1 R = 0.02, POD2 R = 0.38), but not in the protocol patients (POD0 R = -0.05, POD1 R = -0.08, POD2 R = -0.04). There was a shorter length of stay in the protocol cohort (2.0 vs 3.0, P < 0.01). Finally, there was an approximately 35% reduction in morphine milligram equivalents of opioids in the protocol vs preprotocol cohorts (36.2 vs 57.0, P < 0.05).

CONCLUSION

Our novel multimodal pain management protocol significantly reduced postoperative pain, length of stay, and opioid consumption in this patient cohort. Opioid usage correlated to pain in the protocol patients, while the preprotocol patients had no correlation between opioid use and pain medication.

CLINICAL RELEVANCE

In this study, we demonstrated that preoperative and intraoperative analgesia can reduce postoperative pain medication requirements. Furthermore, we introduced a novel concept of a correlation of pain with opioid consumption as a marker of effective pain management of breakthrough pain.

LEVEL OF EVIDENCE: 4

Oxycodone, an opioid like the others?

The over-prescription of opioid analgesics is a growing problem in the field of addiction, which has reached epidemic-like proportions in North America. Over the past decade, oxycodone has gained attention as the leading opioid responsible for the North America opioid crisis. Oxycodone is the most incriminated drug in the early years of the epidemic of opioid use disorder in USA (roughly 1999-2016). The number of preclinical articles on oxycodone is rapidly increasing. Several publications have already compared oxycodone with other opioids, focusing mainly on their analgesic properties. The aim of this review is to focus on the genomic and epigenetic regulatory features of oxycodone compared with other opioid agonists. Our aim is to initiate a discussion of perceptible differences in the pharmacological response observed with these various opioids, particularly after repeated administration in preclinical models commonly used to study drug dependence potential.

L-cysteine ethyl ester prevents and reverses acquired physical dependence on morphine in male Sprague Dawley rats

The molecular mechanisms underlying the acquisition of addiction/dependence on morphine may result from the ability of the opioid to diminish the transport of L-cysteine into neurons via inhibition of excitatory amino acid transporter 3 (EAA3). The objective of this study was to determine whether the co-administration of the cell-penetrant L-thiol ester, L-cysteine ethyl ester (L-CYSee), would reduce physical dependence on morphine in male Sprague Dawley rats. Injection of the opioid-receptor antagonist, naloxone HCl (NLX; 1.5 mg/kg, IP), elicited pronounced withdrawal phenomena in rats which received a subcutaneous depot of morphine (150 mg/kg) for 36 h and were receiving a continuous infusion of saline (20 μL/h, IV) via osmotic minipumps for the same 36 h period. The withdrawal phenomena included wet-dog shakes, jumping, rearing, fore-paw licking, 360° circling, writhing, apneas, cardiovascular (pressor and tachycardia) responses, hypothermia, and body weight loss. NLX elicited substantially reduced withdrawal syndrome in rats that received an infusion of L-CYSee (20.8 μmol/kg/h, IV) for 36 h. NLX precipitated a marked withdrawal syndrome in rats that had received subcutaneous depots of morphine (150 mg/kg) for 48 h) and a co-infusion of vehicle. However, the NLX-precipitated withdrawal signs were markedly reduced in morphine (150 mg/kg for 48 h)-treated rats that began receiving an infusion of L-CYSee (20.8 μmol/kg/h, IV) at 36 h. In similar studies to those described previously, neither L-cysteine nor L-serine ethyl ester (both at 20.8 μmol/kg/h, IV) mimicked the effects of L-CYSee. This study demonstrates that 1) L-CYSee attenuates the development of physical dependence on morphine in male rats and 2) prior administration of L-CYSee reverses morphine dependence, most likely by intracellular actions within the brain. The lack of the effect of L-serine ethyl ester (oxygen atom instead of sulfur atom) strongly implicates thiol biochemistry in the efficacy of L-CYSee. Accordingly, L-CYSee and analogs may be a novel class of therapeutics that ameliorate the development of physical dependence on opioids in humans.

Prenatal alcohol exposure promotes NLRP3 inflammasome-dependent immune actions following morphine treatment and paradoxically prolongs nerve injury-induced pathological pain in female mice

BACKGROUND

Neuroimmune dysregulation from prenatal alcohol exposure (PAE) may contribute to neurological deficits associated with fetal alcohol spectrum disorders (FASD). PAE is a risk factor for developing peripheral immune and spinal glial sensitization and release of the proinflammatory cytokine IL-1β, which lead to neuropathic pain (allodynia) from minor nerve injury. Although morphine acts on μ-opioid receptors, it also activates immune receptors, TLR4, and the NLRP3 inflammasome that induces IL-1β. We hypothesized that PAE induces NLRP3 sensitization by morphine following nerve injury in adult mice.

METHODS

We used an established moderate PAE paradigm, in which adult PAE and non-PAE control female mice were exposed to a minor sciatic nerve injury, and subsequent allodynia was measured using the von Frey fiber test. In control mice with standard sciatic damage or PAE mice with minor sciatic damage, the effects of the NLRP3 inhibitor, MCC950, were examined during chronic allodynia. Additionally, minor nerve-injured mice were treated with morphine, with or without MCC950. In vitro studies examined the TLR4-NLRP3-dependent proinflammatory response of peripheral macrophages to morphine and/or lipopolysaccharide, with or without MCC950.

RESULTS

Mice with standard sciatic damage or PAE mice with minor sciatic damage developed robust allodynia. Blocking NLRP3 activation fully reversed allodynia in both control and PAE mice. Morphine paradoxically prolonged allodynia in PAE mice, while control mice with minor nerve injury remained stably non-allodynic. Allodynia resolved sooner in nerve-injured PAE mice without morphine treatment than in morphine-treated mice. MCC950 treatment significantly shortened allodynia in morphine-treated PAE mice. Morphine potentiated IL-1β release from TLR4-activated PAE immune cells, while MCC950 treatment greatly reduced it.

CONCLUSIONS

In female mice, PAE prolongs allodynia following morphine treatment through NLRP3 activation. TLR4-activated PAE immune cells showed enhanced IL-1β release with morphine via NLRP3 actions. Similar studies are needed to examine the adverse impact of morphine in males with PAE. These results are predictive of adverse responses to opioid pain therapeutics in individuals with FASD.

Extracellular vesicles-Mediators of opioid use disorder?

Opioid use disorder (OUD) is a growing health emergency in the United States leading to an epidemic of overdose deaths. OUD is recognized as an addictive brain disorder resulting in psychological, cognitive and behavioural dysfunction. These observed clinical dysfunctions are a result of cellular changes that occur in the brain. Derangements in inflammation, neurogenesis and synaptic plasticity are observed in the brains of OUD patients. The mechanisms of these derangements are unclear; however, extracellular vesicles (EVs), membrane bound particles containing protein, nucleotides and lipids are currently being investigated as agents that invoke these cellular changes. The primary function of EVs is to facilitate intercellular communication by transfer of cargo (protein, nucleotides and lipids) between cells; however, changes in this cargo have been observed in models of OUD suggesting that EVs may be agents promoting the observed cellular derangements. This review summarizes evidence that altered cargo of EVs, specifically protein and miRNA, in models of OUD promote impairments in neurons, astrocytes and microglial cells. These findings support the premise that opioids alter EVs to detrimentally affect neuro-cellular function resulting in the observed addictive, psychological and neurocognitive deficits in OUD patients.

Maternal care behavior and physiology moderate offspring outcomes following gestational exposure to opioids

The opioid epidemic has resulted in a drastic increase in gestational exposure to opioids. Opioid-dependent pregnant women are typically prescribed medications for opioid use disorders ("MOUD"; e.g., buprenorphine [BUP]) to mitigate the harmful effects of abused opioids. However, the consequences of exposure to synthetic opioids, particularly BUP, during gestation on fetal neurodevelopment and long-term outcomes are poorly understood. Further, despite the known adverse effects of opioids on maternal care, many preclinical and clinical studies investigating the effects of gestational opioid exposure on offspring outcomes fail to report on maternal care behaviors. Considering that offspring outcomes are heavily dependent upon the quality of maternal care, it is important to evaluate the effects of gestational opioid exposure in the context of the mother-infant dyad. This review compares offspring outcomes after prenatal opioid exposure and after reduced maternal care and integrates this information to potentially identify common underlying mechanisms. We explore whether adverse outcomes after gestational BUP exposure are due to direct effects of opioids in utero, deficits in maternal care, or a combination of both factors. Finally, suggestions for improving preclinical models of prenatal opioid exposure are provided to promote more translational studies that can help to improve clinical outcomes for opioid-dependent mothers.

Dexmedetomidine versus Opioids on Labor Analgesia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Effective control of labor pain is critical to the birthing experience. Dexmedetomidine is an alternative adjunct to labor analgesia without the risk of opioid-related adverse effects. The purpose of this study was to examine the efficacy and safety of neuraxial dexmedetomidine versus neuraxial opioids in labor analgesia. PubMed, CINAHL, Cochrane, Google Scholar, and grey literature were searched for evidence. Risk ratio and mean difference (MD) were used to estimate outcomes. The quality of evidence was assessed using the Risk of Bias and GRADE system. Sixteen studies including 1,669 patients were analyzed. Compared with opioids, dexmedetomidine prolonged the duration of analgesia (MD, 47.58 minutes; 95% confidence interval [CI], 1.57 to 93.58; P = .04), reduced pain score (MD, -0.71; 95% CI, -1.17 to -0.24; P = .003), and shortened the onset of analgesia (MD, -1.14 minutes; 95% CI, -1.93 to -0.35; P = .005). Dexmedetomidine did not affect the duration of first and second stages of labor, number of spontaneous, assisted, and cesarean delivery. Additionally, dexmedetomidine had little to no effects on maternal and neonatal outcomes. Neuraxial dexmedetomidine is more favorable than neuraxial opioids for labor analgesia. Extrapolation of the findings to clinical practice should take into considerations the review limitations.

Should opioids be used for breathlessness and in whom? A PRO and CON debate of the evidence

Purpose of review

The net clinical benefit of opioids for chronic breathlessness has been challenged by recent randomized clinical trials. The purpose was to review and weigh the evidence for and against opioid treatment for chronic breathlessness in people with serious disease.

Recent findings

Evidence to date on the efficacy and safety of opioids for chronic breathlessness was reviewed. Findings supporting a benefit from opioids in meta-analyses of earlier, mostly smaller trials were not confirmed by recent larger trials. Evidence pertains mostly to people with chronic obstructive pulmonary disease but also to people with pulmonary fibrosis, heart failure, and advanced cancer. Taken together, there is no consistent evidence to generally recommend opioids for severe breathlessness or to identify people who are more likely to benefit. Opioid treatment may be tested in patients with intractable breathlessness and limited other treatment options, such as in end-of-life care. Knowledge gaps were identified and recommendations were made for future research.

Summary

Key Points Supportive findings of net benefit of opioids for chronic breathlessness in earlier trials have not been confirmed by recent larger randomized clinical trials. There is no evidence that the opioid treatment improves the person’s exercise capacity or quality of life, and it increases the risk of adverse events. Evidence to date does not support that opioids should generally be recommended for treating breathlessness. In people with intractable symptoms and short expected survival, with few or no treatment options, it may still be reasonable to try opioid treatment with the aim to alleviate severe breathlessness. Research is needed to explore the potential benefit of opioids in selected patient groups. Opioids cannot be generally recommended for treating breathlessness based on insufficient evidence for net clinical benefit.

Comparing Post-operative Opioid Consumption before and after a Patient-Controlled Analgesia Shortage: A Re-evaluation of Safety and Effectiveness

This retrospective cohort study aimed to compare post-surgical opioid consumption before and after a PCA (patient-controlled analgesia) shortage. The study evaluated patients who received PCA vs. nurse-administered opioid analgesia (non-PCA). Two hundred and twenty-four patients ≥18 years who were initiated on analgesia within 24 h of surgery were included. The primary outcome was opioid consumption in average daily oral morphine milliequivalents (MME). The results showed that patients in the PCA group had increased MME consumption (162 ± 100.4 vs. 70.7 ± 52.8, p < 0.01), increased length of hospital stay (4.2 vs. 3.2 days, p < 0.01), and increased frequency of nausea (33 vs. 17.9%, p < 0.01). After controlling for confounding factors, the PCA group utilized significantly more opioids (84.6 MME/day, p < 0.01) than the non-PCA group. There was no difference in pain AUC/T (0.19 ± 0.07 vs. 0.21 ± 0.08, p = 0.07) and average opioid prescribing upon discharge (150 [77.5-360] vs. 90 [77.5-400], p = 0.64) between the PCA group and non-PCA group, respectively. These results question the routine use of PCA in post-operative patients due to the increased risk of opioid consumption, longer length of hospital stay, and higher incidence of nausea.

Experimental Study: Interleukin-31 Augments Morphine-Induced Antinociceptive Activity and Suppress Tolerance Development in Mice

Morphine-induced antinociception is partially reduced in interleukin-31 (IL-31) receptor A (IL-31RA)-deficient mice, indicating that IL-31RA is crucial for morphine-induced peripheral antinociception. Herein, we examined the combined effects of IL-31 and morphine on the antinociceptive activity and itch-associated scratching behavior (LLS) in mice and elucidated the regulatory mechanisms. A hot-plate test was used to assess antinociception. LLS was automatically detected and recorded via a computer. IL-31RA mRNA expression was assessed using real-time polymerase chain reaction. Repeated pre-treatment with IL-31 resulted in significant antinociceptive activity. Repeated administration of morphine decreased the morphine-induced antinociceptive activity, LLS counts, and regular dose and inhibited IL-31-induced LLS. These results suggested that the repeated administration of morphine depleted inter-neuronal IL-31RA levels, preventing morphine-induced antinociception. Therefore, IL-31 may be helpful as an adjunct analgesic to morphine. To explore the benefits of IL-31, its influence on morphine-induced antinociceptive tolerance in mice was examined. An IL-31 and morphine combination increased the analgesic action, which increased the expression of DRG neuronal IL-31RA, elucidating the site of peripheral antinociception of morphine. This site may induce exocytosis of IL-31RA in the sensory nervous system. Collectively, the suppressive effect of IL-31 on morphine-induced antinociceptive tolerance may result from IL-31RA supplementation in sensory nerves.

Neuroplasticity of the extended amygdala in opioid withdrawal and prolonged opioid abstinence

Opioid use disorder is characterized by excessive use of opioids, inability to control its use, a withdrawal syndrome upon discontinuation of opioids, and long-term likelihood of relapse. The behavioral stages of opioid addiction correspond with affective experiences that characterize the opponent process view of motivation. In this framework, active involvement is accompanied by positive affective experiences which gives rise to "reward craving," whereas the opponent process, abstinence, is associated with the negative affective experiences that produce "relief craving." Relief craving develops along with a hypersensitization to the negatively reinforcing aspects of withdrawal during abstinence from opioids. These negative affective experiences are hypothesized to stem from neuroadaptations to a network of affective processing called the "extended amygdala." This negative valence network includes the three core structures of the central nucleus of the amygdala (CeA), the bed nucleus of the stria terminalis (BNST), and the nucleus accumbens shell (NAc shell), in addition to major inputs from the basolateral amygdala (BLA). To better understand the major components of this system, we have reviewed their functions, inputs and outputs, along with the associated neural plasticity in animal models of opioid withdrawal. These models demonstrate the somatic, motivational, affective, and learning related models of opioid withdrawal and abstinence. Neuroadaptations in these stress and motivational systems are accompanied by negative affective and aversive experiences that commonly give rise to relapse. CeA neuroplasticity accounts for many of the aversive and fear-related effects of opioid withdrawal via glutamatergic plasticity and changes to corticotrophin-releasing factor (CRF)-containing neurons. Neuroadaptations in BNST pre-and post-synaptic GABA-containing neurons, as well as their noradrenergic modulation, may be responsible for a variety of aversive affective experiences and maladaptive behaviors. Opioid withdrawal yields a hypodopaminergic and amotivational state and results in neuroadaptive increases in excitability of the NAc shell, both of which are associated with increased vulnerability to relapse. Finally, BLA transmission to hippocampal and cortical regions impacts the perception of conditioned aversive effects of opioid withdrawal by higher executive systems. The prevention or reversal of these varied neuroadaptations in the extended amygdala during opioid withdrawal could lead to promising new interventions for this life-threatening condition.

Investigating the Influence of Morphine and Cocaine on the Mesolimbic Pathway Using a Novel Microimaging Platform

Dopamine (DA)'s relationship with addiction is complex, and the related pathways in the mesocorticolimbic system are used to deliver DA, regulating both behavioral and perceptual actions. Specifically, the mesolimbic pathway connecting the ventral tegmental area (VTA) and the nucleus accumbens (NAc) is crucial in regulating memory, emotion, motivation, and behavior due to its responsibility to modulate dopamine. To better investigate the relationship between DA and addiction, more advanced mapping methods are necessary to monitor its production and propagation accurately and efficiently. In this study, we incorporate dLight1.2 adeno-associated virus (AAV) into our latest CMOS (complementary metal-oxide semiconductor) imaging platform to investigate the effects of two pharmacological substances, morphine and cocaine, in the NAc using adult mice. By implanting our self-fabricated CMOS imaging device into the deep brain, fluorescence imaging of the NAc using the dLight1.2 AAV allows for the visualization of DA molecules delivered from the VTA in real time. Our results suggest that changes in extracellular DA can be observed with this adapted system, showing potential for new applications and methods for approaching addiction studies. Additionally, we can identify the unique characteristic trend of DA release for both morphine and cocaine, further validating the underlying biochemical mechanisms used to modulate dopaminergic activation.

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.

HIV-1 and opiates modulate miRNA profiles in extracellular vesicles

Opiate abuse increases the risk of HIV transmission and exacerbates HIV neuropathology by increasing inflammation and modulating immune cell function. Exosomal EVs(xEV) contain miRNAs that may be differentially expressed due to HIV infection or opiate abuse. Here we develop a preliminary exosomal-miRNA biomarker profile of HIV-infected PBMCs in the context of opiate use. PBMCs infected with HIV were treated with increasing dosages of morphine for 72 hours, the culture supernatants were collected, and the exosomes isolated using differential centrifugation. Exosomal miRNAs were extracted, expression levels determined via Nanostring multiplexed microRNA arrays, and analyzed with Webgestalt. The effect of the exosomes on neuronal function was determined by measuring calcium. Preliminary findings show that HIV-1 infection altered the miRNA profile of PBMC-derived EVs concurrently with opiate exposure. MicroRNA, hsa-miR-1246 was up-regulated 12-fold in the presence of morphine, relative to uninfected control. PBMCs infected with HIV-1 MN, an X4-tropic HIV-1 strain and exposed to morphine, displayed a trend which suggests potential synergistic effects between HIV-1 infection and morphine exposure promoting an increase in viral replication. Dose-dependent differences were observed in miRNA expression as a result of opiate exposure. The xEVs derived from PBMCs exposed to morphine or HIV modulated neuronal cell function. SH-SY5Y cells, treated with xEVs derived from ART-treated PBMCs, exhibited increased viability while for SH-SY5Ys exposed to xEVs derived from HIV-1 infected PBMCs viability was decreased compared to the untreated control. Exposing SH-SY5Y to xEVs derived from HIV-infected PBMCs resulted in significant decrease in calcium signaling, relative to treatment with xEVs derived from uninfected PBMCs. Overall, HIV-1 and morphine induced differential miRNA expression in PBMC-derived exosomes, potentially identifying mechanisms of action or novel therapeutic targets involved in opiate use disorder, HIV neuropathology, TNF signaling pathway, NF-κB signaling pathway, autophagy, and apoptosis in context of HIV infection.

Erector spinae plane block for post-operative analgesia in thoracolumbar spine surgery: A randomised controlled trial

Background and Aims

Thoracolumbar spine surgery is one of the most painful surgical procedures. This study's primary objective was to evaluate the effect of erector spinae plane (ESP) block on post-operative cumulative morphine consumption at 24 h in patients undergoing thoracolumbar spine surgery.

Methods

Seventy adults posted for thoracolumbar spine surgery were randomised into the control group [Number of patients (n)=35], who received general anaesthesia without any nerve block, and the intervention group (n = 35), who received bilateral ultrasound (US)-guided ESP block at the level of spine surgery with 0.25% bupivacaine 20 mL after standard general anaesthesia. Along with intravenous patient-controlled analgesia morphine, post-operative analgesia was standardised for both groups. Total morphine consumption, visual analogue scale (VAS) score to evaluate pain, overall patient satisfaction, and any side effects were compared at 24 h. The statistical analysis was done using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL).

Results

Post-operative total morphine consumption at 24 h was significantly decreased in the intervention group compared to the control group [5.69 (1.549) versus 9.51 (1.634) mg; P < 0.001]. Post-operative VAS scores were also significantly decreased in the intervention group at rest (P < 0.001) and on movement (P < 0.001). Patient satisfaction scores were more favourable in the intervention group [3.8 (0.4) versus 3.2 (0.6); P < 0.001]. Post-operative nausea and vomiting were found more in the control group but were not significant (n = 14 versus 8; P = 0.127).

Conclusion

US-guided ESP block significantly reduces post-operative morphine consumption and improves analgesia and patient satisfaction without adverse effects in patients undergoing thoracolumbar spine surgery.

Morphine in donkeys: Antinociceptive effect and preliminary pharmacokinetics

BACKGROUND

Morphine is the prototypical μ-opioid receptor agonist used to provide analgesia in veterinary species. Its effects are well-described in horses but not donkeys.

OBJECTIVES

To determine the antinociceptive effects of two doses of morphine in donkeys. To describe preliminary pharmacokinetic parameters of morphine in donkeys.

STUDY DESIGN

In vivo experiment.

METHODS

Eight adult castrated male donkeys were given intravenous (IV) 0.9% saline, morphine 0.1 mg/kg bwt (LDM), or morphine 0.5 mg/kg bwt (HDM) in a randomised order with a minimum 1-week washout period. Mechanical nociceptive thresholds (MNTs) were determined by a blinded investigator pre-injection and 15, 30, 45, 60, 90, 120, 150, 180, 210, 240, 300, and 360 min post-injection. Venous blood samples were collected pre-injection and 2, 5, 10, 15, 30, 45, 60, 90, and 120 min post-injection. Data were analysed using Friedman's test with Dunn's post hoc test for multiple comparisons. Pharmacokinetic parameters were calculated for the HDM treatment.

RESULTS

Baseline MNT was [median (interquartile range)] 8.9 (7.1-10.3) N and did not differ between treatments. Peak MNTs occurred at 60 min for both LDM (16.2 N) and HDM (25.0 N) treatments. MNTs after HDM treatment were higher than saline (p < 0.04) at 15, 60, 90, 120, 150, 180, 240, and 300 min post-injection. MNTs after LDM treatment were higher than baseline (p < 0.05) at 45 and 60 min post-injection. Terminal half-life for HDM was (mean ± SD) 51.0 ± 10.7 min, the volume of distribution at steady-state 2.07 ± 0.33 L/min and clearance 49.2 ± 4.16 ml * min/kg using noncompartmental analysis. The concentration of morphine-3-glucuronide (M3G) was higher than morphine-6-glucuronide (M6G) at all sampled time points.

MAIN LIMITATIONS

Short duration of plasma sampling for pharmacokinetic analysis; lack of objective measure of gastrointestinal function.

CONCLUSIONS

The HDM treatment provided mechanical antinociception in donkeys with no significant adverse effects.

A cholinergic circuit that relieves pain despite opioid tolerance

Chronic pain is a tremendous burden for afflicted individuals and society. Although opioids effectively relieve pain, significant adverse outcomes limit their utility and efficacy. To investigate alternate pain control mechanisms, we explored cholinergic signaling in the ventrolateral periaqueductal gray (vlPAG), a critical nexus for descending pain modulation. Biosensor assays revealed that pain states decreased acetylcholine release in vlPAG. Activation of cholinergic projections from the pedunculopontine tegmentum to vlPAG relieved pain, even in opioid-tolerant conditions, through ⍺7 nicotinic acetylcholine receptors (nAChRs). Activating ⍺7 nAChRs with agonists or stimulating endogenous acetylcholine inhibited vlPAG neuronal activity through Ca2+ and peroxisome proliferator-activated receptor α (PPAR⍺)-dependent signaling. In vivo 2-photon imaging revealed that chronic pain induces aberrant excitability of vlPAG neuronal ensembles and that ⍺7 nAChR-mediated inhibition of these cells relieves pain, even after opioid tolerance. Finally, pain relief through these cholinergic mechanisms was not associated with tolerance, reward, or withdrawal symptoms, highlighting its potential clinical relevance.

The opioid receptor: emergence through millennia of pharmaceutical sciences

Throughout history humanity has searched for an optimal approach to the use of opioids that maximizes analgesia while minimizing side effects. This review reflects upon the conceptualization of the opioid receptor and the critical role that the pharmaceutical sciences played in its revelation. Opium-containing formulations have been delivered by various routes of administration for analgesia and other therapeutic indications for millennia. The concept of a distinct site of opium action evolved as practitioners developed innovative delivery methods, such as intravenous administration, to improve therapeutic outcomes. The introduction of morphine and synthetic opioids engendered the prevalent assumption of a common opioid receptor. Through consideration of structure-activity relationships, spatial geometry, and pharmacological differences of known ligands, the idea of multiple opioid receptors emerged. By accessing the high-affinity property of naloxone, the opioid receptor was identified in central and peripheral nervous system tissue. The endogenous opioid neuropeptides were subsequently discovered. Application of mu-, delta-, and kappa- opioid receptor-selective ligands facilitated the pharmacological characterization and distinctions between the three receptors, which were later cloned and sequenced. Opioid receptor signal transduction pathways were described and attributed to specific physiological outcomes. The crystal structures of mu, delta, kappa, and nociceptin/orphanin FQ receptors bound to receptor-selective ligands have been elucidated. Comparison of these structures reveal locations of ligand binding and engagement of signal transduction pathways. Expanding knowledge regarding the structure and actions of the opioid receptor fuels contemporary strategies for driving the activity of opioid receptors toward maximizing therapeutic and minimizing adverse outcomes.

Therapeutic efficacy of intravenous lidocaine infusion compared with thoracic epidural analgesia in major abdominal surgery: a noninferiority randomised clinical trial

BACKGROUND

Open major abdominal surgery is one of the most risky surgical procedures for acute postoperative pain. Thoracic epidural analgesia (TEA) has been considered the standard analgesic approach. In different reports, lidocaine i.v. has been shown to have an analgesic efficacy comparable with TEA. We compared the analgesic efficacy of i.v. lidocaine with thoracic epidural analgesia using bupivacaine in patients undergoing major abdominal surgery.

METHODS

In this noninferiority clinical trial, 210 patients were randomised to thoracic epidural bupivacaine with morphine or i.v. lidocaine. Dynamic pain at 24 h after surgery was measured using a numerical pain rating scale (NPR), and morphine consumption was also measured. A difference in i.v. the lidocaine-epidural bupivacaine NPR of ≤1 for dynamic pain was considered a noninferiority margin.

RESULTS

The NPR for dynamic pain in the lidocaine group at 24 h was between 5.7 (1.8) and 5.2 (1.9) in the epidural group, with a difference of 0.53 (95% confidence interval 0.0-1.0). In the first 24 h, the average difference in morphine consumption was 1.8 mg between the i.v. lidocaine and epidural groups (95% confidence interval 1-3 mg). No differences were found in adverse events or complications associated with the procedures.

CONCLUSIONS

Intravenous lidocaine is noninferior to thoracic epidural analgesia for acute postoperative pain control in major abdomial surgery at 24 h postoperatively.

CLINICAL TRIALS REGISTRATION

NCT04017013.

Effect of oral clonidine on pain reduction in patients with opioid use disorder in the emergency department: A randomized clinical trial

AIMS

Pain can create physical and psychosocial discomfort. Pain management of patients with opioid misuse history can be challenging, in part due to their tolerance to opioids. Clonidine is an alpha-2 agonist that has been used for the reduction of anxiety and pain. The aim of this study was to investigate the effect of oral clonidine on pain outcomes in patients with a history of opioid use disorder presenting with orthopaedic fractures in the emergency room.

METHODS

In this blinded clinical trial in the emergency department, 70 opioid-dependent patients with orthopaedic fractures were divided into a control group of 35 and an intervention group of 35 subjects. Initially, 0.2 mg of oral clonidine was given to the intervention group and the control group received placebo tablets. Pain levels were recorded based on the Numerical Rating Scale rating before intervention, at 30 min, 1 h after intervention and at disposition from the emergency room (3-6 h after intervention). The total morphine requirement was also recorded.

RESULTS

The pain score of the clonidine group was significantly lower than that of the control group at 1 h and at disposition time. The amount of morphine required was significantly reduced in the clonidine group (P < 0.05). Oral clonidine had no significant effect on pulse rate. Oral clonidine was more effective for pain reduction in lower limb injuries.

CONCLUSION

Oral clonidine significantly reduced pain and the need for morphine in opioid-dependent patients with orthopaedic fractures.

Immunomodulatory properties of morphine and the hypothesised role of long-term opioid use in the immunopathogenesis of tuberculosis

Epidemiological studies have shown high tuberculosis (TB) prevalence among chronic opioid users. Opioid receptors are found on multiple immune cells and immunomodulatory properties of opioids could be a contributory factor for ensuing immunosuppression and development or reactivation of TB. Toll-like receptors (TLR) mediate an immune response against microbial pathogens, including Mycobacterium tuberculosis. Mycobacterial antigens and opioids co-stimulate TLRs 2/4/9 in immune cells, with resulting receptor cross-talk via multiple cytosolic secondary messengers, leading to significant immunomodulatory downstream effects. Blockade of specific immune pathways involved in the host defence against TB by morphine may play a critical role in causing tuberculosis among chronic morphine users despite multiple confounding factors such as socioeconomic deprivation, Human immunodeficiency virus co-infection and malnutrition. In this review, we map out immune pathways involved when immune cells are co-stimulated with mycobacterial antigens and morphine to explore a potential immunopathological basis for TB amongst long-term opioid users.

The Role of the Cerebellum in Drug Reward: A Review

Drug abuse remains a global problem; nonetheless, its mechanism has not yet been fully understood. Recent studies have reported on the non-motor functions of the cerebellum, and evidence from neuroimaging and behavioral studies has suggested the role of cerebellum in drug reward, which has received increasing attention. Furthermore, emerging technological developments have aided in clarifying the various circuits and functions of the cerebellum. Exploring the role of the cerebellum in drug reward can improve our understanding of the mechanism underlying addiction and facilitate the development of new treatment schemes. This review summarizes the anatomy of the cerebellum and its connections to brain regions considered important in addiction. Subsequently, we investigate the neurological reasons elucidating why the cerebellum is a potential target for drug reward. Additionally, we expound the molecular targets of addictive drugs in the cerebellum, mainly glutamate and endocannabinoids. Unlike previous studies, this article focuses on the influence of alcohol, nicotine, morphine, cannabis, and cocaine on the cerebellum from multiple viewpoints, including imaging and behavioral changes, molecular signals, neurotransmitters, and synaptic transmission. We aim to clarify some drug-induced cerebellar changes to supplement the previous research regarding the relationship between addiction and the cerebellum. Finally, we discuss the limitations and prospects of drug reward research on the cerebellum to provide novel insights into studying the cerebellum and its role in addiction. We recommend that future addiction network models should include the cerebellum to provide new therapeutic targets for treating addiction.