Tapentadol Immediate Release (IR) versus Morphine Hydrochloride for Postoperative Analgesia of Patients Undergoing Total Abdominal Hysterectomy-A Prospective Cohort Study

Background and Objectives: This study aimed to examine the efficacy of tapentadol immediate release (IR) and morphine hydrochloride in the treatment of acute postoperative pain after total abdominal hysterectomy, as well as to examine the frequency of opioid-related side effects in observed patients. Materials and Methods: The prospective observational study was conducted over five months, and it included a total number of 100 patients. The two cohorts had different types of postoperative analgesia, and the effects were observed for 24 h postoperatively, by following the pain scores on NRS (Numerical Pain Scale), contentment with analgesia, and opioid-related side effects. Results: Statistical significance was found when assessing pain 24 h after surgery while coughing, where patients in the tapentadol IR group had significantly higher mean pain scores (p < 0.01). The subjective feeling of satisfaction with postoperative analgesia was statistically significant in the tapentadol IR group (p = 0.005). Vertigo appeared significantly more in patients from the morphine group (p = 0.03). Conclusions: Tapentadol IR (immediate release) and morphine hydrochloride are both effective analgesics used in the first 24 h after total transabdominal hysterectomy. Overall satisfaction of patients with analgesia was good. The frequency of side effects was higher in the morphine group, with statistical significance regarding the vertigo.

Perioperative Analgesia and Patients' Satisfaction in Spinal Anesthesia for Cesarean Section: Fentanyl Versus Morphine

Perioperative analgesia for cesarean section aims to ensure the mother's comfort, facilitate a smooth surgical experience, and promote a successful recovery. One-hundred-ninety patients were enrolled in a randomized double-blind study designed to assess the quality of perioperative analgesia, level of satisfaction, and incidence of adverse reactions in elective cesarean section under spinal anesthesia when fentanyl or morphine was added to bupivacaine. Two treatment groups comprising 173 subjects were compared in the per-protocol analysis: F (fentanyl, standard dose 25 μg) and M (morphine, standard dose 100 μg). Numerical pain scores were recorded perioperatively for 72 h (both at rest and on mobilization), with overall postoperative satisfaction and analgesic-related side effects. The patients in the morphine group had significantly better pain management (Mann-Whitney U test, p < 0.001) and higher level of satisfaction (Mann-Whitney U test, p < 0.001). The latter was related to the greater need for rescue medication in the fentanyl group (OR = 4.396; p = 0.019). On the other hand, fentanyl had significantly fewer non-life-threatening side effects, such as high-intensity pruritus (Mann-Whitney U test, p < 0.001), nausea (OR = 0.324; p = 0.019), vomiting and dizziness upon first mobilization (OR = 0.256; p < 0.001). It remains for future clinical trials to help establish doses that will tilt the scale to one side or the other.

Comparison of the Efficacies of Three Different Intrathecal Doses of Morphine in Achieving Postcesarean Delivery Analgesia

PURPOSE

The objective of this study is to compare the efficacies of 3 different intrathecal doses (80, 120, and 160 mcg) of morphine in achieving postcesarean delivery analgesia and the severity of the side effects thereof.

DESIGN

A prospective, randomized, double-blind study.

METHODS

A total of 150 pregnant women between the ages of 18 and 40, with a gestational week >36, who were planned to have elective cesarean section were included in the study. Patients were randomized into 3 groups based on the dosages of intrathecal doses of morphine (80, 120, and 160 mcg) they will receive in addition to 10 mg 0.5% hyperbaric bupivacaine and 20 mcg fentanyl. Intravenous (IV) patient-controlled analgesia (PCA) prepared with fentanyl was administered to each patient after the surgery. Postoperative 24-hour total IV PCA-fentanyl consumption was recorded. The patients were evaluated for side effects such as pain, nausea-vomiting, pruritus, sedation score, and respiratory depression after the surgery.

FINDINGS

PCA-fentanyl consumption was significantly higher in Group 1 compared to Group 2 and 3 (P = .047). There was no significant differences between the groups in terms of nausea-vomiting scores. The pruritus scores were significantly higher in Group 3 compared to Group 1 (P = .020). The pruritus scores were significantly higher in all groups at the postoperative 8th-hour (P = .013). Respiratory depression, which would require treatment, was not observed in any patient.

CONCLUSIONS

Based on the study findings, it was concluded that 120 mcg intrathecal morphine provides adequate analgesia with minimal side effects in cesarean sections.

Sufentanil Sublingual Tablet System vs. Intravenous Patient-Controlled Analgesia with Morphine: Postoperative Pain Control and Its Impact in Quality of Recovery

CONTEXT

Patient-controlled analgesia (PCA) is commonly used for postoperative pain control. Although widely used, intravenous (IV) morphine PCA may not be suitable for all patients. Sufentanil sublingual tablet system (SSTS) PCA is a recent technique that has had success as a safe and effective alternative for acute pain management.

AIMS

This study aims to compare both the efficacy and safety of SSTS PCA versus IV morphine PCA in postoperative pain control and the quality of recovery in adult patients following scheduled gynecological or orthopedic surgery.

SETTINGS AND DESIGN

Open-label, parallel-group, randomized controlled trial with 54 patients. The primary outcome was postoperative pain control, while the secondary outcomes included adverse effects associated with two analgesic modalities, total opioid dose required, patient satisfaction, and impact on the quality of postoperative recovery.

METHODS AND MATERIAL

Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 26.0 (Released 2019; IBM Corp., Armonk, New York, United States). The chi-squared test was used in categorical variables. When distribution was normal, T-student (mean ± standard deviation) was used in continuous variables. In contrast, when distribution was not normal, the Mann-Whitney test (median (minimal-maximal)) was used.

RESULTS

The results showed that there was a statistically significant difference in the total dose of opioid used by patients at 24 hours postoperatively, with patients receiving SSTS PCA requiring a higher total dose when compared to those receiving IV morphine PCA. However, there were no statistically significant differences in pain scores, adverse events, or patient satisfaction.

CONCLUSIONS

The study suggests that both IV morphine and sublingual sufentanil are safe and effective for postoperative pain management.

Inhibitory effect of berberine on morphine tolerance and hyperalgesia in mice

OBJECTIVE

To evaluate the effect of berberine on morphine analgesia, tolerance, and hyperalgesia.

METHODS

Morphine-induced acute tolerance model: mice received intraperitoneal berberine at doses of 2.5, 5.0, and 10 mg/kg; 30 min later, subcutaneous morphine 10 mg/kg was injected every hour for nine continuous h. Morphine 10 mg/kg alone was administered at 24 and 48 h. Morphine-induced chronic tolerance model: mice received intraperitoneal berberine 2.5, 5.0, and 10 mg/kg; 30 min later, 10 mg/kg morphine was injected subcutaneously for eight consecutive days. On the ninth day, morphine 10 mg/kg was given alone. Morphine-induced established tolerance model: mice were injected subcutaneously with morphine 10 mg/kg once a day for eight consecutive days. Berberine 2.5 mg/kg was administered on day one, four, and seven and morphine 10 mg/kg alone on day nine. The baseline latency (T0) and post-treatment latency (T1) were determined by the hot plate test, and the maximum possible analgesic effect (MPAE) was calculated. Nitric oxide synthase (NOS) activity and nitric oxide (NO) content in the spinal cord were measured by spectrophotometer. Verification of berberine analgesic effect by blocking N-methyl-D-aspartate (NMDA) receptor: HT-22 and HEK-293 cells transfected with NMDA plasmid were randomly divided into five groups: control group, NMDA group, berberine low-dose, medium-dose, and high-dose groups (5, 10, 20 μmol/L, respectively). Except for the control group, cells were treated with NMDA (HT-22 cells: 20 mmol/L; HEK-293 cells: 50 μmol/L). After 24 h, cell viability was detected by cell counting kit-8. The molecular mechanism between berberine and the NMDA receptor was studied by molecular docking.

RESULTS

Berberine 2.5 and 5.0 mg/kg could prolong the analgesic time of morphine. In acute and chronic morphine tolerance models, berberine could inhibit the decrease of MPAE and baseline latency (0.05). In the established tolerance model, berberine could rapidly reverse the decreased MPAE (0.05). The combination of berberine and morphine on day one could effectively inhibit the morphine-induced increase of NOS activity and NO content in the spinal cord (0.05). Berberine significantly increased the cell viability of NMDA-induced nerve injury in HT-22 and HEK-293 cells (0.05). Molecular docking showed that berberine binds to the receptor pocket of NMDA.

CONCLUSIONS

Berberine could effectively enhance and prolong the duration of morphine analgesia and inhibit the development of morphine-induced tolerance and hyperalgesia. Furthermore, berberine has a certain neuroprotective effect, which may be related to the inhibition of NMDA activity.

Increased LPS-Induced Fever and Sickness Behavior in Adult Male and Female Rats Perinatally Exposed to Morphine

As a result of the current opioid crisis, the rate of children born exposed to opioids has skyrocketed. Later in life, these children have an increased risk for hospitalization and infection, raising concerns about potential immunocompromise, as is common with chronic opioid use. Opioids can act directly on immune cells or indirectly via the central nervous system to decrease immune system activity, leading to increased susceptibility, morbidity, and mortality to infection. However, it is currently unknown how perinatal opioid exposure (POE) alters immune function. Using a clinically relevant and translatable model of POE, we have investigated how baseline immune function and the reaction to an immune stimulator, lipopolysaccharide, is influenced by in utero opioid exposure in adult male and female rats. We report here that POE potentiates the febrile and neuroinflammatory response to lipopolysaccharide, likely as a consequence of suppressed immune function at baseline (including reduced antibody production). This suggests that POE increases susceptibility to infection by manipulating immune system development, consistent with the clinical literature. Investigation of the mechanisms whereby POE increases susceptibility to pathogens is critical for the development of potential interventions for immunosuppressed children exposed to opioids in utero.

Whole-Body Vibration Prevents Neuronal, Neurochemical, and Behavioral Effects of Morphine Withdrawal in a Rat Model

Peripheral mechanoreceptor-based treatments such as acupuncture and chiropractic manipulation have shown success in modulating the mesolimbic dopamine (DA) system originating in the ventral tegmental area (VTA) of the midbrain and projecting to the nucleus accumbens (NAc) of the striatum. We have previously shown that mechanoreceptor activation via whole-body vibration (WBV) ameliorates neuronal and behavioral effects of chronic ethanol exposure. In this study, we employ a similar paradigm to assess the efficacy of WBV as a preventative measure of neuronal and behavioral effects of morphine withdrawal in a Wistar rat model. We demonstrate that concurrent administration of WBV at 80 Hz with morphine over a 5-day period significantly reduced adaptations in VTA GABA neuronal activity and NAc DA release and modulated expression of δ-opioid receptors (DORs) on NAc cholinergic interneurons (CINs) during withdrawal. We also observed a reduction in behavior typically associated with opioid withdrawal. WBV represents a promising adjunct to current intervention for opioid use disorder (OUD) and should be examined translationally in humans.

Methodology and findings of randomized clinical trials on pharmacologic and non-pharmacologic interventions to treat renal colic pain - a review

Introduction

Renal colic pain is considered one of the most excruciating pains ever experienced and ranks as one of the most common urological emergencies. Despite existing established recommendations, new therapies and their combinations are continuously being tested. The aim of this systematic review is to analyze and compare studies involving pharmacologic and non-pharmacologic interventions used in the treatment of renal colic pain.

Material and methods

This systematic review was conducted following the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Medline, Scopus, Cochrane Library, and Google Scholar were searched for relevant randomized controlled trials (RCTs) involving adult patients. The quality and results of the included studies were assessed and discussed.

Results

This review provides an extensive analysis of 71 identified RCTs. Opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and dipyrone/metamizole have demonstrated effectiveness as single medications. Some evidence points to opioids having a potential disadvantage compared to others when used as a first-line single medication. Among the 63 studies exploring pharmacological therapy, 51 reported opioids utilization for rescue therapy in significant proportion of patients. Promising combination therapies involve the administration of an NSAID alongside opioids, ketamine, desmopressin, steroids, or nitric oxide. Conversely, spasmolytics, magnesium, and lidocaine exhibited limited or no additional effect. Noteworthy methodological shortcomings encompass a low pain threshold during participant recruitment and the reliance on pain reduction rather than complete pain elimination as an endpoint.

Conclusions

Frequent use of opioids as rescue medications in RCTs undermine their conclusions on effectiness of other therapeutics. Combination therapies should be considered as first choice in renal colic pain management. RCTs should define success of therapy as achieving complete or near-complete pain relief rather than pain reduction.

N-palmitoylethanolamide synergizes the antinociception of morphine and gabapentin in the formalin test in mice

OBJECTIVE

The antinociceptive pharmacological interaction between N-palmitoylethanolamide (PEA) and morphine (MOR), as well as gabapentin (GBP), was investigated to obtain synergistic antinociception at doses where side effects were minimal. In addition, the possible antinociceptive mechanism of PEA + MOR or PEA + GBP combinations was explored.

METHODS

Individual dose-response curves (DRCs) of PEA, MOR and GBP were evaluated in female mice in which intraplantar nociception was induced with 2% formalin. Isobolographic method was used to detect the pharmacological interaction in the combination of PEA + MOR or PEA + GBP.

KEY FINDINGS

The ED50 was calculated from the DRC; the order of potency was MOR > PEA > GBP. The isobolographic analysis was obtained at a 1:1 ratio to determine the pharmacological interaction. The experimental values of flinching (PEA + MOR, Zexp = 2.72 ± 0.2 μg/paw and PEA + GBP Zexp = 2.77 ± 0.19 μg/paw) were significantly lower than those calculated theoretically (PEA + MOR Zadd = 7.78 ± 1.07 and PEA + GBP Zadd = 24.05 ± 1.91 μg/paw), resulting in synergistic antinociception. Pretreatment with GW6471 and naloxone demonstrated that peroxisome proliferator-activated receptor alpha (PPARα) and opioid receptors are involved in both interactions.

CONCLUSIONS

These results suggest that MOR and GBP synergistically enhance PEA-induced antinociception through PPARα and opioid receptor mechanisms. Furthermore, the results suggest that combinations containing PEA with MOR or GBP could be of interest in aiding the treatment of inflammatory pain.

Management of cancer pain in pregnancy: can opioids be used?

Cancer in pregnancy is less common, however its frequency is increasing due to delayed onset of childbearing. Pregnant patients with cancer can experience high frequency of moderate to severe cancer pain. It can be challenging to manage cancer pain due to the complexity with assessment and treatment as many of the analgesics are avoided. There exists limited research and few guidelines by national and international organizations to guide effective opioid management among pregnant women or pregnant woman with cancer pain. Pregnant patients with cancer need to be managed by interdisciplinary team with multimodal analgesia including opioids, adjuvants, non-pharmacological interventions for optimal care of these patient and later the neonate. Opioids such as morphine may be considered for the management of severe cancer pain during pregnancy. It is important to prescribe the lowest effective dose and quantity of opioids after taking into consideration the risk/benefit to patient-infant dyad. Neonatal abstinence syndrome should be anticipated after delivery and carefully managed in intensive care, if possible. Further research is needed. In this review article we describe the challenges of managing cancer pain in pregnant woman and the current approach of opioids management for cancer pain in these patients using a case report.

Comparison of the analgesic effect of intrathecal morphine between laparoscopic and open living donor hepatectomy: Propensity score matching analysis

Laparoscopic donor hepatectomy is being increasingly adopted in transplant programs due to its numerous advantages. However, the role of intrathecal morphine (ITM) in laparoscopic donor hepatectomy has not been thoroughly investigated. This study aimed to compare the analgesic effects and safety of ITM between laparoscopic and open donor hepatectomy. This retrospective study included 742 donors who underwent hepatectomy with ITM between April 2007 and June 2019. Among them, 168 and 574 donors underwent laparoscopic hepatectomy (LH) and open hepatectomy (OH), respectively. Propensity score matching yielded two comparable groups of 168 donors each. The primary endpoint was the incidence of moderate-to-severe pain (maximum numerical rating scale [NRS] pain score ≥ 4) within 24 postoperative hours. The LH group had a significantly lower incidence of moderate-to-severe pain within 24 postoperative hours than the OH group (16.1% vs 64.3%, P < .001). Moreover, the cumulative rescue intravenous opioids (in morphine-equivalent dose) on postoperative day (POD) 1 was lower in the LH group than in the OH group (3.3 [0-8.3] mg vs 10 [3.3-17.3] mg; P < .001). There were no significant between-group differences in the incidence of respiratory depression (2.4% vs 0.6%; P = .371) and prescriptions for pruritus (14.3% vs 15.5%; P = .878). However, the prescriptions for postoperative nausea and vomiting (PONV) was significantly higher in the LH group than in the OH group (64.9% vs 41.7%; P < .001). The predictors of antiemetic agent prescription included the use of laparoscopic procedure (adjusted odds ratio [OR], 2.05; 95% confidence interval [CI], 1.11-3.79; P = .021) and female sex (adjusted OR, 5.63; 95% CI, 3.19-9.92; P < .001). Preoperative ITM administration resulted in a significantly lower incidence of moderate-to-severe pain within 24 postoperative hours after laparoscopic donor hepatectomy than after open donor hepatectomy.

A Randomised Controlled Study on Epidural Morphine and Bupivacaine for Post-Operative Analgesia After Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Randomised control study.

OBJECTIVE

Different parenteral analgesics are used to alleviate post-operative pain after transforaminal lumbar interbody fusion (TLIF) but limited by their efficacy and side effects. We performed a RCT to evaluate the safety and efficacy of epidural Morphine-Bupivacaine on post-operative pain management after TLIF.

METHODS

Consecutive patients (n=100) of TLIF were divided randomly into study (SG) and control groups (CG). At the end of procedure, SG (n=50) received epidural instillation of morphine 5 mg and bupivacaine .25% - 2 mL, along with 6 mL of .25% bupivacaine infiltration in the deep fascia before wound closure. The functional outcomes were assessed at regular intervals (4, 8, 12, 24, 36, 48, 72, 96 hours) with VAS, nausea and vomiting scale, Ramsay sedation scale and breakthrough analgesia needed, time to ambulation and other complications.

RESULTS

The mean VAS score at 4 hours in SG was significantly less (1.16 ± .88) than the CG (3.32 ± 1.0) (P = .000). This significant difference was maintained at each time point during the first 48 hours (P < .004). Similarly, the mean NRS score in SG at 4 hours was 1.02 ± .89, and in CG 3.3 ± .69 (P = .0000) which was maintained at all intervals of assessment till 48 hours (P = .0137). The mean time to first ambulation was significantly less in the SG (4.46 ± 1.04 hours) than CG (11.64 ± 2.3 hours) (P < .001). There were no drug-related complications.

CONCLUSION

Epidural instillation of bupivacaine and morphine is safe and enables better pain relief in the initial 48 hours which helps in early mobilisation, and enhanced functional recovery.

Perceptions of Barriers to Using Opioid Analgesics: A Mixed Methods Study

Background

Availability and accessibility of opioids are a worldwide problem. In low-resource settings, such as Ethiopia, access to opioids is either limited or nonexistent and legally restricted in health care settings. This study aimed to identify barriers for the availability and accessibility of opioids in Ethiopian rural and regional health care settings.

Methods

A mixed-method case study design was used. A total of 220 nurses from primary, secondary, and tertiary health care settings were invited to participate in a survey of knowledge and practice. For the qualitative interview, 38 participants were recruited from educational facilities, health services, and the community across a region.

Results

Barriers in availability and accessibility of opioid analgesics were expressing pain considered as a sign of weakness, lack of knowledge, side effect concerns about prescribing morphine, only doctors being authorized to prescribe morphine, lack of foreign currency to import morphine ingredients, and inequity in accessing morphine in hospitals and none in rural health care settings.

Conclusion

The findings of this study indicate that opioids, particularly morphine, were not consistently available and accessible to all patients in need. Health professionals lacked knowledge about opioids. Strengthening the existing pain-free initiatives and improving the type, dose, and supply of morphine could help reduce needless suffering and enhance access to essential pain medicines for those in need.

Impact of Opioids on Cellular Metabolism: Implications for Metabolic Pathways Involved in Cancer

Opioid utilization for pain management is prevalent among cancer patients. There is significant evidence describing the many effects of opioids on cancer development. Despite the pivotal role of metabolic reprogramming in facilitating cancer growth and metastasis, the specific impact of opioids on crucial oncogenic metabolic pathways remains inadequately investigated. This review provides an understanding of the current research on opioid-mediated changes to cellular metabolic pathways crucial for oncogenesis, including glycolysis, the tricarboxylic acid cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS). The existing literature suggests that opioids affect energy production pathways via increasing intracellular glucose levels, increasing the production of lactic acid, and reducing ATP levels through impediment of OXPHOS. Opioids modulate pathways involved in redox balance which may allow cancer cells to overcome ROS-mediated apoptotic signaling. The majority of studies have been conducted in healthy tissue with a predominant focus on neuronal cells. To comprehensively understand the impact of opioids on metabolic pathways critical to cancer progression, research must extend beyond healthy tissue and encompass patient-derived cancer tissue, allowing for a better understanding in the context of the metabolic reprogramming already undergone by cancer cells. The current literature is limited by a lack of direct experimentation exploring opioid-induced changes to cancer metabolism as they relate to tumor growth and patient outcome.

Gabapentin as Adjunctive Therapy in Neonatal Opioid Withdrawal Syndrome: A Case Series

OBJECTIVE

We describe a single center experience with gabapentin as adjunctive therapy in infants with neonatal opioid withdrawal syndrome (NOWS).

METHODS

We performed a retrospective chart review of infants receiving gabapentin for NOWS. Data points collected included patient's sex, gestational age, maternal opioid exposure, NOWS medication dosing and length of therapy, number of failed wean attempts, time to successful morphine wean and duration of morphine wean, length of stay in the neonatal intensive care unit (NICU), and NOWS medications at discharge.

RESULTS

Six infants received gabapentin as adjunctive treatment for NOWS. All infants failed 2-4 morphine weans before initiation of gabapentin despite the addition of clonidine. All infants that received gabapentin were successfully weaned off morphine. The time to wean off morphine after gabapentin initiation varied from 4-35 days. Maximum gabapentin doses ranged from 15 - 42.7 mg/kg/day. Five infants were discharged from the NICU on gabapentin.

CONCLUSIONS

Gabapentin appeared to facilitate successful morphine weans in six patients with NOWS who were previously unable to wean despite the initiation of clonidine.

Morphine Analgesia, Cannabinoid Receptor 2, and Opioid Growth Factor Receptor Cancer Tissue Expression Improve Survival after Pancreatic Cancer Surgery

Pancreatic cancer (PDAC) has a poor prognosis despite surgical removal and adjuvant therapy. Additionally, the effects of postoperative analgesia with morphine and piritramide on survival among PDAC patients are unknown, as are their interactions with opioid/cannabinoid receptor gene expressions in PDAC tissue. Cancer-specific survival data for 71 PDAC patients who underwent radical surgery followed by postoperative analgesia with morphine (n = 48) or piritramide (n = 23) were therefore analyzed in conjunction with opioid/cannabinoid receptor gene expressions in the patients' tumors. Receptor gene expressions were determined using the quantitative real-time polymerase chain reaction. Patients receiving morphine had significantly longer cancer-specific survival (CSS) than those receiving piritramide postoperative analgesia (median 22.4 vs. 15 months; p = 0.038). This finding was supported by multivariate modelling (p < 0.001). The morphine and piritramide groups had similar morphine equipotent doses, receptor expression, and baseline characteristics. The opioid/cannabinoid receptor gene expression was analyzed in a group of 130 pancreatic cancer patients. Of the studied receptors, high cannabinoid receptor 2 (CB2) and opioid growth factor receptor (OGFR) gene expressions have a positive influence on the length of overall survival (OS; p = 0.029, resp. p = 0.01). Conversely, high delta opioid receptor gene expression shortened OS (p = 0.043). Multivariate modelling indicated that high CB2 and OGFR expression improved OS (HR = 0.538, p = 0.011, resp. HR = 0.435, p = 0.001), while high OPRD receptor expression shortened OS (HR = 2.264, p = 0.002). Morphine analgesia, CB2, and OGFR cancer tissue gene expression thus improved CSS resp. OS after radical PDAC surgery, whereas delta opioid receptor expression shortened OS.

Pharmacological Treatments and Therapeutic Drug Monitoring in Patients with Chronic Pain

Pain is an unpleasant sensory and emotional experience that affects every aspect of a patient's life and which may be treated through different pharmacological and non-pharmacological approaches. Analgesics are the drugs most commonly used to treat pain, and in specific situations, the use of opioids may be considered with caution. These drugs, in fact, do not always induce optimal analgesia in patients, and several problems are associated with their use. The purpose of this narrative review is to describe the pharmacological approaches currently used for the management of chronic pain. We review several aspects, from the pain-scale-based methods currently available to assess the type and intensity of pain, to the most frequently administered drugs (non-narcotic analgesics and narcotic analgesics), whose pharmacological characteristics are briefly reported. Overall, we attempt to provide an overview of different pharmacological treatments while also illustrating the relevant guidelines and indications. We then report the strategies that may be used to reduce problems related to opioid use. Specifically, we focus our attention on therapeutic drug monitoring (TDM), a tool that could help clinicians select the most suitable drug and dose to be used for each patient. The actual potential of using TDM to optimize and personalize opioid-based pain treatments is finally discussed based on recent scientific reports.

The Role of Morphine-Induced Impairment of Intestinal Epithelial Antibacterial Activity in Dysbiosis and its Impact on the Microbiota-Gut-Brain Axis

Recent evidence suggests that chronic exposure to opioid analgesics such as morphine disrupt the intestinal epithelial layer and cause intestinal dysbiosis. Inhibiting opioid-induced dysbiosis can preclude the development of tolerance to opioid-induced antinociception, suggesting an important role of the gut-brain axis in mediating opioid effects. However, the mechanism underlying opioid-induced dysbiosis remains unclear. Host-produced antimicrobial peptides (AMPs) are critical for the integrity of the intestinal epithelial barrier as they prevent the pathogenesis of the enteric microbiota. Here, we report that chronic morphine exposure reduces expression of the antimicrobial peptide, Regenerating islet-derived 3 gamma (Reg3γ), in the ileum resulting in reduced intestinal antimicrobial activity against Gram-positive bacteria, L. reuteri. Fecal samples from morphine-treated mice had reduced levels of the phylum, Firmicutes, concomitant with reduced levels of short-chain fatty acid, butyrate. Fecal microbial transplant (FMT) from morphine-naïve mice restored the antimicrobial activity, the expression of Reg3γ, and prevented the increase in intestinal permeability and the development of antinociceptive tolerance in morphine-dependent mice. Similarly, oral gavage with sodium butyrate dose-dependently reduced the development of antinociceptive tolerance, and prevented the downregulation of Reg3γ and the reduction in antimicrobial activity. The alpha diversity of the microbiome was also restored by oral butyrate in morphine-dependent mice. These data implicate impairment of the antimicrobial activity of the intestinal epithelium as a mechanism by which morphine disrupts the microbiota-gut-brain axis.

Intrathecal Morphine versus Morphine-Dexmedetomidine Combination for Postoperative Pain Control After Total Knee Replacement: A Randomized Controlled Trial

Objective

This prospective study aimed to compare the analgesic efficacy and adverse effects of intrathecal morphine, dexmedetomidine, and a combination of both in patients undergoing total knee replacement (TKR).

Patients and Methods

This randomized prospective study was carried out in Tanta university hospital in orthopedic surgery for 6 months on 105 adult patients with American Society of Anesthesiologists Physical Status Class II and III, aged > 50 years, and scheduled for total knee replacement surgery randomly allocated into morphine group received 0.5% heavy bupivacaine plus 0.1 mg of morphine, morphine/ dexmedetomidine group, received 0.5% heavy bupivacaine plus 0.1 mg of morphine and 5 mcg of dexmedetomidine and dexmedetomidine group received 0.5% heavy bupivacaine plus 5 mcg of dexmedetomidine. The time of the first required analgesia, postoperative pain severity, the total dose of morphine, postoperative complication, and the patient's level of sedation were recorded.

Results

About half of the patients in the dexmedetomidine group requested first rescue analgesia 6 hours after the operation, significantly shorter than the other two groups. On the other hand, the other two groups show no significant difference between them regarding the first required analgesia. At rest, the dexmedetomidine group have significantly higher VAS with a significant increase in patients who required morphine as rescue analgesia than the other two groups. While at movement, patients in the dexmedetomidine group felt pain at 4 hrs postoperatively with significantly higher VAS than the other two groups. At the same time, the sedation score was significantly lower in the dexmedetomidine group than in the other two groups. 22.2% of cases in the morphine group developed nausea and vomiting with a significant difference between the three groups.

Conclusion

Despite the absence of substantial side effects, our findings did not suggest enhanced analgesia with the combination of intrathecal morphine and dexmedetomidine.

A Comparative Study of Morphine and Clonidine as an Adjunct to Ropivacaine in Paravertebral Block for Modified Radical Mastectomy

Background General anesthesia (GA) is a standard for breast malignant surgery. The issue of postoperative pain as well as the high occurrence of nausea and vomiting have prompted the quest for a superior methodology for tormenting the executives with fewer complications. Over the most recent couple of years, paravertebral block (PVB) has acquired huge fame either in combination with GA or alone for anesthetic management. In this study, we aim to evaluate the efficacy of morphine and clonidine as an adjunct to ropivacaine in PVB in breast cancer patients undergoing modified radical mastectomy. Methods In this study, a total of 90 patients were divided into the following three groups (30 each) based on a computer-generated random table. Group C (control): PVB with 0.25% ropivacaine (19 ml) 1 ml saline; Group M: PVB with 0.25% ropivacaine (19 ml) + 20 microgram/kg body weight morphine; Group N: PVB with 0.25% ropivacaine (19 ml) + 1.0 microgram/kg body weight clonidine. The postoperative pain intensity was recorded using the visual analog scale (VAS), and sedation was observed by the Ramsay Sedation Scale (RSS) score. Results The VAS was similar at zero hours, two hours, and four hours in the postoperative period among all the groups. There was a significant (p = 0.003) difference in VAS from six hours to 20 hours in the postoperative period among the groups. A significant (p < 0.05) difference was observed among the groups at eight hours to 20 hours. The first requirement of analgesia was significantly (p = 0.001) higher in Group N (7.70 ± 1.74) than in Group C (4.43 ± 1.43) and Group M (7.33 ± 2.21). Conclusion Morphine in the PVB provides better postoperative analgesia. The consumption of rescue analgesia was significantly reduced in the morphine group as compared to the clonidine group. The procedure also proved to be safe as no complication was encountered in the PVB in our study.

P-glycoprotein (MDR1/ABCB1) Restricts Brain Penetration of the Main Active Heroin Metabolites 6-monoacetylmorphine (6-MAM) and Morphine in Mice

BACKGROUND & PURPOSE

Heroin (diacetylmorphine; diamorphine) is a highly addictive opioid prodrug. Heroin prescription is possible in some countries for chronic, treatment-refractory opioid-dependent patients and as a potent analgesic for specific indications. We aimed to study the pharmacokinetic interactions of heroin and its main pharmacodynamically active metabolites, 6-monoacetylmorphine (6-MAM) and morphine, with the multidrug efflux transporters P-glycoprotein/ABCB1 and BCRP/ABCG2 using wild-type, Abcb1a/1b and Abcb1a/1b;Abcg2 knockout mice.

METHODS & RESULTS

Upon subcutaneous (s.c.) heroin administration, its blood levels decreased quickly, making it challenging to detect heroin even shortly after dosing. 6-MAM was the predominant active metabolite present in blood and most tissues. At 10 and 30 min after heroin administration, 6-MAM and morphine brain accumulation were increased about 2-fold when mouse (m)Abcb1a/1b and mAbcg2 were ablated. Fifteen minutes after direct s.c. administration of an equimolar dose of 6-MAM, we observed good intrinsic brain penetration of 6-MAM in wild-type mice. Still, mAbcb1 limited brain accumulation of 6-MAM and morphine without affecting their blood exposure, and possibly mediated their direct intestinal excretion. A minor contribution of mAbcg2 to these effects could not be excluded.

CONCLUSIONS

We show that mAbcb1a/1b can limit 6-MAM and morphine brain exposure. Pharmacodynamic behavioral/postural observations, while non-quantitative, supported moderately increased brain levels of 6-MAM and morphine in the knockout mouse strains. Variation in ABCB1 activity due to genetic polymorphisms or environmental factors (e.g., drug interactions) might affect 6-MAM/morphine exposure in individuals, but only to a limited extent.

Oral morphine induces spinal 5-hydroxytryptamine (5-HT) release using an opioid receptor-independent mechanism

Morphine induces spinal 5-hydroxytryptamine (5-HT) release, but the role and mechanism of the spinal 5-HT release induced by morphine are not well understood. The purpose of this study was to define the role and mechanism of spinal 5-HT release induced by oral morphine. We also examined whether persistent pain affected the spinal 5-HT release induced by oral morphine. Spinal 5-HT release was measured using microdialysis of lumbar cerebrospinal fluid (CSF). Two opioids, morphine and oxycodone, were orally administered and 5-HT release was measured in awake rats. Naloxone and β-funaltrexamine (β-FNA) were used to determine whether the effect of morphine on 5-HT release was mediated by opioid receptor activation. To study persistent pain, a formalin test was used. At 45 min after oral morphine administration, the formalin test was started and spinal 5-HT release was measured. Oral morphine, but not oral oxycodone, increased 5-HT release at the spinal cord to approximately 4000% of the baseline value. This effect of morphine was not antagonized by either naloxone or β-FNA at a dose that antagonized the antinociceptive effect of morphine. Formalin-induced persistent pain itself had no effect on spinal 5-HT release but enhanced the oral morphine-induced spinal 5-HT release. Oral morphine-induced spinal 5-HT release was not mediated by opioid receptor activation. Spinal 5-HT induced by oral morphine did not play a major role in the antinociceptive effect of morphine in the hot plate test. Persistent pain increased oral morphine-induced spinal 5-HT release.