Nausea and Vomiting Side Effects with Opioid Analgesics during Treatment of Chronic Pain: Mechanisms, Implications, and Management Options

Gastrointestinal disorders - Clinical challenges for the primary care clinician

Gastrointestinal (GI) associated symptoms are among the most common medical concerns resulting in visits to primary and specialty care. Especially challenging is the wide range of causative disorders and exposures associated with symptoms ranging from mild to life threatening - from within the GI tract as well as extra-gastrointestinal. Some of these are well described, and common, including infections, while others are newly emerging, such as cannabinoid hyperemesis syndrome. Others are well known but clinical success can remain elusive, such as food associated GI disorders - lactose intolerance and related. Although entire references have been written to address gastrointestinal diseases, in this edition of Disease a Month we will address some of the more challenging GI disorders; some of which are common but often difficult to control - food associated for example, and emerging GI illnesses such as radiation or cannabinoid hyperemesis, that lead patients to the Emergency Department, primary care clinician or specialty referral. What follows is a discussion of diverse but clinically important GI disorders, and the newer therapeutic strategies to help patients better manage their symptoms, and improve their quality of life.

Synergistic Antiemetic Effects of Nerolidol on Domperidone, Hyoscine, and Ondansetron: In Vivo and in Silico Investigations on Receptor Binding Affinity

The present study was designed to measure the potential antiemetic properties of nerolidol (NDL) via in vivo and in silico studies. To induce emesis copper sulfate pentahydrate (CuSO4.5H2O) was administered at a dose of 50 mg/kg (orally) to 2-day-old chicks. The test sample (NDL) was given at two doses of 50 and 100 mg/kg. b.w. orally. Additionally, aprepitant (16 mg/kg), domperidone (6 mg/kg), hyoscine (21 mg/kg), ondansetron (5 mg/kg), and diphenhydramine (10 mg/kg) were given also orally as positive controls. To observe the modulatory effects of the test sample, combination therapies with reference drugs were also administered to three different groups of animals. Molecular docking and visualization of ligand-receptor interaction were performed against several emesis-inducing receptors (5HT3, D2, D3, H1, and M1-M5) using diverse computational tools. Pharmacokinetics and drug-likeness of the selected ligands were also calculated. Findings demonstrated that NDL significantly (p <0.05) dose-dependently lessens the mean number of retches and delays the emetic onset in the chicks. The combined drug therapy with ondansetron exposed better antiemetic activity. In addition, in silico analysis, NDL has greater binding affinity (-7.3 kcal/mol) against M2 and M3 receptors. In conclusion, NDL exerted mild antiemetic activity with synergistic properties through muscarinic receptors.

TMEM132C rs7296262 Single-Nucleotide Polymorphism Is Significantly Associated with Nausea Induced by Opioids Administered for Cancer Pain and Postoperative Pain

Opioids are almost mandatorily used for analgesia for cancer pain and postoperative pain. Opioid analgesics commonly induce nausea as a side effect. However, the genetic factors involved are still mostly unknown. To clarify the genetic background of individual differences in the occurrence of nausea during opioid administration, the incidence of nausea was investigated in 331 patients (Higashi-Sapporo Hospital [HS] group) who received morphine chronically for cancer pain treatment and in 2021 patients (Cancer Institute Hospital [CIH] group) who underwent elective surgery under general anesthesia. We conducted a genome-wide association study of nausea in HS samples. Among the top 20 candidate single-nucleotide polymorphisms (SNPs), we focused on the TMEM132C rs7296262 SNP, which has been reportedly associated with psychiatric disorders. The rs7296262 SNP was significantly associated with nausea in both the HS and CIH groups (TT+TC vs. CC; HS group, p = 0.0001; CIH group, p = 0.0064). The distribution of nausea-prone genotypes for the rs7296262 SNP was reversed between HS and CIH groups. These results suggest that the TMEM132C rs7296262 SNP is significantly associated with nausea during opioid use, and the effect of the SNP genotype on nausea is reversed between chronic and acute phases of opioid use.

[Appropriate use of strong opioids in medical units: Recommendations and action to be taken in daily practice]

The use of strong opioids in medical units is recurrent, mainly for analgesic purposes. The risk of occurrence of an overdose or an opioid use disorders causes very legitimate concerns for the physician, which may limit the use of opioid treatment or the adaptation of the doses necessary to relieve the patient. We provide a summary of the literature aimed at defining the indications, the adverse effects and the risks involved, the prescribing methods in order to reassure professionals and promote the safe use of these molecules.

Pharmacological treatment of cancer pain and opioid induced nausea and vomiting: online survey and comparison with current guidelines

PURPOSE

We assumed that in Palliative Care, even in common clinical situations, the choice of drugs differs substantially between physicians. Therefore, we assessed the practice of pharmaceutical treatment choices of physicians for cancer pain and opioid-induced nausea and vomiting (OINV) and the rationale for their choices.

METHODS

An online survey was conducted with physicians covering the following domains: i) Cancer pain therapy: non-opioids in addition to opioids: choice of drug ii) prevention of OINV: choice of drug and mode of application. Current guidelines concerning cancer pain therapy and prevention of OINV were compared.

RESULTS

Two-hundred-forty European physicians responded to our survey. i) Use of non-opioids in addition to opioids for the treatment of cancer pain: Only 1.3% (n = 3) of respondents never used an additional non-opioid. Others mostly used: dipyrone/metamizole (49.2%, n = 118), paracetamol/acetaminophen (34.2%, n = 82), ibuprofen / other NSAIDs (11.3%, n = 27), specific Cox2-inhibitors (2.1%, n = 5), Aspirin (0.4%, n = 1), no answer (2.9%, n = 7). ii) Antiemetics to prevent OINV: The drugs of choice were metoclopramide (58.3%, n = 140), haloperidol (26.3%, n = 63), 5-HT3 antagonists (9.6%, n = 23), antihistamines (1.3%, n = 3) and other (2.9%, n = 7); no answer (1.7%, n = 4). Most respondents prescribed the substances on-demand (59.6%, n = 143) while others (36.3%, n = 87) provided them as around the clock medication. Over both domains, most physicians answered that their choices were not based on solid evidence from randomized controlled trials (RCTs). Guidelines were inconsistent regarding if and what non-opioid to use for cancer pain and recommend anti-dopaminergic drugs for prevention or treatment of OINV.

CONCLUSIONS

Physician's practice in palliative care for the treatment of cancer pain and OINV differed substantially. Respondents expressed the lack of high-quality evidence- based information from RCTs. We call for evidence from methodologically high-quality RCTs to be available to inform physicians about the benefits and harms of pharmacological treatments for common symptoms in palliative care.

Safe Management of Adverse Effects Associated with Prescription Opioids in the Palliative Care Population: A Narrative Review

In the palliative care population, prescription opioids are often considered viable pain relief options. However, in this complex patient population, the adverse effects of opioid medications should be identified and managed without delay. Common adverse effects can include constipation, nausea, somnolence, dizziness, vomiting, and pruritus. Less common adverse effects can include potentially lethal respiratory depression and cardiovascular effects. Critical aspects of safe opioid prescribing are recognition of side effects and knowledge of effective management strategies; prompt management is necessary for uninterrupted pain relief. Most complications are managed with general approaches such as dose reduction, opioid rotation, alternate routes of administration, and symptomatic management. The only opioid-induced complication for which US Food and Drug Administration-approved treatments currently exist is constipation. Treating laxative-refractory opioid-induced constipation (OIC) with peripherally acting mu-opioid receptor antagonists (PAMORAs), which block gastrointestinal opioid receptors, can restore gastrointestinal motility and fluid secretion. This narrative review discusses key complications of prescription opioid treatment and their management in the palliative care setting.

Sick of Feeling Sick: Management of Opioid Treatment-Induced Refractory Nausea Resulting in Suicidal Ideations With a Plan and Intent

In this case report, we present the case of a 60-year-old Caucasian male with a history of depression, anxiety, opioid dependence, and idiopathic polyneuropathy, admitted to an inpatient psychiatric unit for suicidal ideation. The patient's symptoms were characterized by months of intractable nausea, severe anxiety, suicidal ideation (SI), and significant unintentional weight loss in the context of methadone-assisted treatment. Over nine days in the hospital, a treatment strategy was developed and refined, which eventually achieved sustained relief from nausea and significant improvement in anxiety. The most effective pharmacological interventions included mirtazapine, scopolamine, and gabapentin.

Thermoresponsive Polymeric Hydromorphone Prodrug Provides Sustained Local Analgesia without Apparent Adverse Effects

The extensive use of opioids for chronic pain management has contributed significantly to the current opioid epidemic. While many alternative nonopioid analgesics are available, opioids remain the most potent analgesics for moderate to severe pain management. In addition to the implementation of multimodal analgesia, there is a pressing need for the development of more effective and safer opioids. In this study, we developed a thermoresponsive N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based hydromorphone (HMP) prodrug (ProGel-HMP, HMP content = 16.2 wt %, in base form). The aqueous solution of ProGel-HMP was free-flowing at 4 °C but became a hydrogel when the temperature was raised to ≥37 °C, allowing sustained local retention when administered in vivo. When tested in the destabilization of the medial meniscus (DMM) mouse model of osteoarthritis (OA), ProGel-HMP was retained after intra-articular injection in the OA knee joint for at least 2 weeks postinjection, with low extra-articular distribution. ProGel-HMP was not detected in the central nervous system (CNS). A single dose of ProGel-HMP produced rapid and sustained joint pain resolution for greater than 14 days when compared to saline and dose-equivalent HMP controls, likely mediated through peripheral μ-opioid receptors in the knee joint. Systemic analgesia effect was absent in the DMM mice treated with ProGel-HMP, as evident in the lack of difference in tail flick response between the ProGel-HMP-treated mice and the controls (i.e., Healthy, Saline, and Sham). Repeated dosing of ProGel-HMP did not induce tolerance. Collectively, these data support the further development of ProGel-HMP as a potent, safe, long-acting and nonaddictive analgesic for better clinical pain management.

Analysis of Nausea and Vomiting Frequency Following Opioid Dose Escalation and Its Risk Factors: A Single-Center Retrospective Observational Study

Background and Objective: Opioid-induced nausea and vomiting (OINV) is known to develop not only upon opioid introduction but also during opioid dose escalation, but the actual details are unclear. The aim of this study was to investigate the frequency of OINV in opioid dose escalation at a single center and to identify risk factors. Methods: A retrospective analysis of the medical records of hospitalized patients with cancer who underwent increased intake of oral oxycodone extended-release tablets at Komaki City Hospital between January 2016 and December 2019 was performed. Associations between the incidence of OINV and multiple factors were analyzed, including patient demographics, opioid daily dose, comorbidities, history of nausea after opioid introduction, and prophylactic antiemetic drugs. Results: Of the 132 patients analyzed, 56 (42.4%; grades 1 and 2, 36 and 20, respectively) developed opioid-induced nausea after opioid dose escalation, 26 (19.7%; grades 1 and 2, 19 and 7, respectively) developed opioid-induced vomiting, 58 (43.9%) had either opioid-induced nausea or vomiting. Thirty-five of 60 patients (55.0%) developed OINV among those who received prophylactic antiemetic drugs at opioid dose escalation. Performance status (≥2) (odds ratio [OR]: 2.36, 95% confidence interval [95% CI]: 1.15-4.84, p = 0.02) and history of nausea for opioid introduction (OR: 2.92, 95% CI: 1.20-7.10, p = 0.02) were detected as risk factors for the development of OINV. Conclusion: This study revealed a high incidence of OINV during opioid dose escalation, indicating that careful monitoring is required as at the time of opioid introduction. Further validation by a prospective study is required.

External treatment of traditional Chinese medicine for cancer pain: A systematic review and network meta-analysis

BACKGROUND

Cancer pain is one of the most intolerable and frightening symptoms of cancer patients. However, the clinical effect of the three-step analgesic ladder method (TSAL) is not satisfactory. The combination of external treatment of traditional Chinese medicine (TCM) can improve the clinical effect.

OBJECTIVE

This study used network meta-analysis to compare the effects of different external treatment methods of TCM combined with TSAL on cancer pain.

METHODS

Databases searched by our team included Google Scholar, Web of Science, Scopus, Embase, PubMed, and Cochrane Library. Randomized controlled trials related to the external treatment of TCM combined with TSAL for cancer pain were screened from the establishment of the database till now. The above literature extracted clinical efficacy, NRS score, KPS score, analgesic onset time, and duration as the main results after the screening. The 95% confidence interval (95% CI) of OR value and SMD value was used as the effect index to compare the difference in efficacy of different interventions, and the ranking was conducted. STATA 17.0 software was used for the statistical analysis of the above data.

RESULTS

A total of 78 studies were included, including 8 interventions and 5742 participants. Based on ranking probability, the clinical effective rate of manual acupuncture combined with TSAL was the best when the intervention time was set at 4 weeks [OR = 5.42, 95% CI (1.99,14.81)], and the improvement effect on KPS score was also the best [SMD = 0.97, 95% CI (0.61, 1.33)]. Acupoint external application was the best intervention in reducing NRS score [SMD = -1.14, 95% CI (-1.90, -0.93)]. Acupoint moxibustion combined with TSAL was considered to be the most effective intervention to prolong the duration of analgesia [SMD = 1.69, 95% CI (0.84, 2.54)] and shortening the onset time of analgesia [SMD = -3.00, 95% CI (-4.54, -1.47)].

CONCLUSIONS

TSAL combined with manual acupuncture is the best in terms of clinical efficacy and improvement of patients' functional activity status. With the extension of treatment time, the intervention of this kind of treatment on the clinical effect is more pronounced. Acupoint external application also has a unique advantage in reducing the pain level of patients. From the point of view of analgesic duration and duration of analgesia, combined acupoint moxibustion has the best effect.

Coexpressed δ-, μ-, and κ-Opioid Receptors Modulate Voltage-Gated Ca2+ Channels in Gastric-Projecting Vagal Afferent Neurons

Opioid analgesics are frequently associated with gastrointestinal side effects, including constipation, nausea, dysphagia, and reduced gastric motility. Though it has been shown that stimulation of opioid receptors expressed in enteric motor neurons contributes to opioid-induced constipation, it remains unclear whether activation of opioid receptors in gastric-projecting nodose ganglia neurons contributes to the reduction in gastric motility and emptying associated with opioid use. In the present study, whole-cell patch-clamp recordings were performed to determine the mechanism underlying opioid receptor-mediated modulation of Ca2+ currents in acutely isolated gastric vagal afferent neurons. Our results demonstrate that CaV2.2 channels provide the majority (71% ± 16%) of Ca2+ currents in gastric vagal afferent neurons. Furthermore, we found that application of oxycodone, U-50488, or deltorphin II on gastric nodose ganglia neurons inhibited Ca2+ currents through a voltage-dependent mechanism by coupling to the Gα i/o family of heterotrimeric G-proteins. Because previous studies have demonstrated that the nodose ganglia expresses low levels of δ-opioid receptors, we also determined the deltorphin II concentration-response relationship and assessed deltorphin-mediated Ca2+ current inhibition following exposure to the δ-opioid receptor antagonist ICI 174,864 (0.3 µM). The peak mean Ca2+ current inhibition following deltorphin II application was 47% ± 24% (EC50 = 302.6 nM), and exposure to ICI 174,864 blocked deltorphin II-mediated Ca2+ current inhibition (4% ± 4% versus 37% ± 20%). Together, our results suggest that analgesics targeting any opioid receptor subtype can modulate gastric vagal circuits. SIGNIFICANCE STATEMENT: This study demonstrated that in gastric nodose ganglia neurons, agonists targeting all three classical opioid receptor subtypes (μ, δ, and κ) inhibit voltage-gated Ca2+ channels in a voltage-dependent mechanism by coupling to Gαi/o. These findings suggest that analgesics targeting any opioid receptor subtype would modulate gastric vagal circuits responsible for regulating gastric reflexes.

Multimodal Approaches in the Treatment of Chronic Peripheral Neuropathy-Evidence from Germany

Patients with chronic peripheral neuropathy suffer greatly and their quality of life is often restricted. Drug therapy can be accompanied by undesirable side effects and intolerances, or the hoped-for effect does not materialize. Therefore, in addition to drug therapy, attempts are also made to treat the physical symptoms with complementary procedures. In the case of severe forms, the search for a suitable form of therapy is difficult. Complex treatments can be an innovative way to treat peripheral neuropathy. At the same time, several different therapy methods are carried out at high frequency by a specialized treatment team. This study aimed to provide an overview of possible complementary forms of therapy. The focus was on a comparison of two interdisciplinary complex therapies that are used in severe cases in an acute inpatient care setting in Germany. The six dimensions (energy, sleep, pain, physicality, emotional response and social isolation) of the Nottingham Health Profile (NHP) were used to assess quality of life. Both complex treatments (naturopathic complex therapy/multimodal pain therapy) showed a significant reduction in impairment in all dimensions of the NHP. In addition, a multivariate analysis was carried out to take into account several influencing variables at the same time. At the time of admission to the hospital, the degree of chronicity was recorded for each patient. This allowed statements to be made about the effect of the respective therapy depending on the chronification stage of the patient. It has been shown that patients with acutely exacerbated pain with the highest degree of chronicity also benefit from both complex treatments. The naturopathic complex treatment gives the treatment team more options. Aspects such as nutrition, methods from phytotherapy and traditional Chinese medicine can be integrated into inpatient care. Thus, a patient-centered, holistic therapy can take place. However, an interdisciplinary holistic therapy requires more time for both the practitioner and the patient. This should be taken into account in the health systems in the context of the diagnosis related groups.

Peripheral nerve blocks in advanced cancer pain: retrospective case series

OBJECTIVES

Patients with cancer often suffer severe pain that is not relieved with systemic analgesics and requires further treatment options. This study aims to investigate whether peripheral nerve blocks are a feasible treatment option in patients with incurable cancer who suffer from severe pain.

METHODS

All patients with advanced cancer who received a peripheral nerve block for the management of pain at the Tampere University Hospital between January 2015 and December 2018 were included in this retrospective study. The characteristics of the patients' features of the nerve blocks, opioid dosing (daily morphine equivalent) before and after the blocks, and patient-reported pain relief following peripheral block were assessed from the medical records.

RESULTS

Sixteen of the 17 patients included in this study received pain relief through a nerve block. Daily opioid dose was decreased with the block in 12 (71%) patients with a median change in daily morphine equivalent of -20 mg (IQR: -180 to 9). One infection of the catheter and two other transient adverse events occurred, but none was serious or fatal.

CONCLUSIONS

Peripheral nerve blocks seem safe and may provide considerable analgesia and decrease the need for opioids in patients with advanced cancer.

Reducing opioid use for chronic non-cancer pain in primary care using an evidence-based, theory-informed, multistrategic, multistakeholder approach: a single-arm time series with segmented regression

BACKGROUND

Many countries have high opioid use among people with chronic non-cancer pain. Knowledge about effective interventions that could be implemented at scale is limited. We designed a national intervention that included audit and feedback, deprescribing guidance, information on catastrophising assessment, pain neuroscience education and a cognitive tool for use by patients with their healthcare providers.

METHOD

We used a single-arm time series with segmented regression to assess rates of people using opioids before (January 2015 to September 2017), at the time of (October 2017) and after the intervention (November 2017 to August 2019). We used a cohort with historical comparison group and log binomial regression to examine the rate of psychologist claims in opioid users not using psychologist services prior to the intervention.

RESULTS

13 968 patients using opioids, 8568 general practitioners, 8370 pharmacies and accredited pharmacists and 689 psychologists were targeted. The estimated difference in opioid use was -0.51 persons per 1000 persons per month (95% CI -0.69, -0.34; p<0.001) as a result of the intervention, equating to 25 387 (95% CI 24 676, 26 131) patient-months of opioid use avoided during the 22-month follow-up. The targeted group had a significantly higher rate of incident patient psychologist claims compared with the historical comparison group (rate ratio: 1.37, 95% CI 1.16, 1.63; p<0.001), equating to an additional 690 (95% CI 289, 1167) patient-months of psychologist treatment during the 22-month follow-up.

CONCLUSIONS

Our intervention addressed the cognitive, affective and sensory factors that contribute to pain and consequent opioid use, demonstrating it could be implemented at scale and was associated with a reduction in opioid use and increasing utilisation of psychologist services.

Preoperative predictors of prolonged hospitalization in patients undergoing lateral lumbar interbody fusion

PURPOSE

We aim to examine the preoperative factors associated with increased postoperative length of stay in patients undergoing LLIF in the hospital setting.

METHODS

Patient demographics, perioperative characteristics, and patient-reported outcome measures (PROMs) were collected from a single-surgeon database. Patients undergoing LLIF in the hospital setting were separated into postoperative LOS <48 h (H) and LOS ≥ 48H. Univariate analysis for preoperative characteristics was utilized to determine covariates for multivariable logistic regression. Multivariable logistic regression was then utilized to determine significant predictors of extended postoperative length of stay. Secondary univariate analysis of inpatient complications, operative, and postoperative characteristics were calculated to determine postoperative factors associated with prolonged hospitalization.

RESULTS

Two-hundred and forty patients were identified with 115 patients' LOS ≥ 48H. Univariate analysis identified age/Charlson Comorbidity Index (CCI) score/gender/insurance type/number of contiguous fused levels/preoperative PROMs of Visual Analog Scale (VAS) back/VAS leg/Patient-Reported Outcomes Measurement Information System (PROMIS-PF)/Oswestry Disability Index (ODI)/degenerative spondylolisthesis diagnoses/foraminal stenosis/central stenosis for multivariable logistic regression. Multivariable logistic regression calculated significant positive predictors of LOS ≥ 48H to be age/3-level fusion/preoperative ODI scores. Negative predictors of LOS ≥ 48H were the diagnosis of foraminal stenosis/preoperative PROMIS-PF/male gender. The secondary analysis determined that patients with longer operative time/estimated blood loss/transfusion/postoperative day 0 and 1 pain and narcotic consumption/complications of altered mental status/postoperative anemia/fever/ileus/urinary retention were associated with prolonged hospitalization.

CONCLUSION

Older patients undergoing LLIF with greater preoperative disability and 3-level fusion were more likely to require prolonged hospitalization. Male patients with higher preoperative physical function and who were diagnosed with foraminal stenosis were less likely to require prolonged hospitalization.

CYX-5, a G-protein biassed MOP receptor agonist, DOP receptor antagonist and KOP receptor agonist, evokes constipation but not respiratory depression relative to morphine in rats

BACKGROUND

Strong opioid analgesics such as morphine alleviate moderate to severe acute nociceptive pain (e.g. post-surgical or post-trauma pain) as well as chronic cancer pain. However, they evoke many adverse effects and so there is an unmet need for opioid analgesics with improved tolerability. Recently, a prominent hypothesis has been that opioid-related adverse effects are mediated by β-arrestin2 recruitment at the µ-opioid (MOP) receptor and this stimulated research on discovery of G-protein biassed opioid analgesics. In other efforts, opioids with MOP agonist and δ-opioid (DOP) receptor antagonist profiles are promising for reducing side effects c.f. morphine. Herein, we report on the in vivo pharmacology of a novel opioid peptide (CYX-5) that is a G-protein biassed MOP receptor agonist, DOP receptor antagonist and kappa opioid (KOP) receptor agonist.

METHODS

Male Sprague-Dawley received intracerebroventricular bolus doses of CYX-5 (3, 10, 20 nmol), morphine (100 nmol) or vehicle, and antinociception (tail flick) was assessed relative to constipation (charcoal meal and castor oil-induced diarrhoea tests) and respiratory depression (whole body plethysmography).

RESULTS

CYX-5 evoked naloxone-sensitive, moderate antinociception, at the highest dose tested. Although CYX-5 did not inhibit gastrointestinal motility, it reduced stool output markedly in the castor oil-induced diarrhoea test. In contrast to morphine that evoked respiratory depression, CYX-5 increased tidal volume, thereby stimulating respiration.

CONCLUSION

Despite its lack of recruitment of β-arrestin2 at MOP, DOP and KOP receptors, CYX-5 evoked constipation, implicating a mechanism other than β-arrestin2 recruitment at MOP, DOP and KOP receptors, mediating constipation evoked by CYX-5 and potentially other opioid ligands.

Effects of buprenorphine, methadone, and cariprazine on economic choice between remifentanil and food in squirrel monkeys

We recently reported an economic choice task in which squirrel monkeys chose between differing amounts of remifentanil, a fast-acting opioid, or a food reward to develop a preclinical screen for evaluating potential pharmacotherapies for opioid dependence. Herein, two known opioid addiction treatments are evaluated using this task, as well as a potential new agent, cariprazine, a dopamine D2/D3 receptor partial agonist currently used to treat bipolar disorder and schizophrenia. Preclinical rodent studies suggest this class of compounds may reduce opiate self-administration. Squirrel monkeys were pretreated daily with clinically relevant doses of each compound during the five days of treatment evaluation using the economic choice task. Shifts in drug preference were measured as changes in subjects' indifference values, where the probability of drug and milk choice are equivalent. Buprenorphine produced a significant shift in indifference value between baseline and treatment weeks, indicating a decrease in drug preference. Subjects treated with methadone and cariprazine did not show any significant shift in drug preference. Differences between the buprenorphine and methadone results likely reflect a lack of opioid dependence in the subjects. The cariprazine results suggest that it does not alter opioid reward in non-dependent primates over a five day period.

RNA sequencing least shrew (Cryptotis parva) brainstem and gut transcripts following administration of a selective substance P neurokinin NK1 receptor agonist and antagonist expands genomics resources for emesis research

The least shrew is among the subset of animals that are capable of vomiting and therefore serves as a valuable research model for investigating the biochemistry, molecular biology, pharmacology, and genomics of emesis. Both nausea and vomiting are associated with a variety of illnesses (bacterial/viral infections, bulimia, exposure to toxins, gall bladder disease), conditions (pregnancy, motion sickness, emotional stress, overeating) and reactions to drugs (chemotherapeutics, opiates). The severe discomfort and intense fear associated with the stressful symptoms of nausea and emesis are the major reason for patient non-compliance when being treated with cancer chemotherapeutics. Increased understanding of the physiology, pharmacology and pathophysiology underlying vomiting and nausea can accelerate progress for developing new antiemetics. As a major animal model for emesis, expanding genomic knowledge associated with emesis in the least shrew will further enhance the laboratory utility of this model. A key question is which genes mediate emesis, and are they expressed in response to emetics/antiemetics. To elucidate the mediators of emesis, in particular emetic receptors, their downstream signaling pathways, as well as the shared emetic signals, we carried out an RNA sequencing study focused on the central and peripheral emetic loci, the brainstem and gut. Thus, we sequenced RNA extracted from brainstem and gut tissues from different groups of least shrews treated with either a neurokinin NK1 receptor selective emetic agonist, GR73632 (5 mg/kg, i.p.), its corresponding selective antagonist netupitant (5 mg/kg, i.p.), a combination of these two agents, versus their corresponding vehicle-pretreated controls and drug naïve animals. The resulting sequences were processed using a de novo transcriptome assembly and used it to identify orthologs within human, dog, mouse, and ferret gene sets. We compared the least shrew to human and a veterinary species (dog) that may be treated with vomit-inducing chemotherapeutics, and the ferret, another well-established model organism for emesis research. The mouse was included because it does not vomit. In total, we identified a final set of 16,720 least shrew orthologs. We employed comparative genomics analyses as well as gene ontology enrichment, KEGG pathway enrichment and phenotype enrichment to better understand the molecular biology of genes implicated in vomiting.

Modulation of inflammatory mediators involved in the antinociceptive and anti-inflammatory effects of a new thioamide derivative: thiocyanoacetamide

Inflammatory pain is part of the body's defense mechanism and plays an important role in the healing process. Although some drugs are efficient and intensively used for their potent anti-inflammatory properties, they present problematic side effects. The aim of this study was to evaluate the anti-nociceptive effect of the thiocyanoacetamide (Thm) compared to paracetamol (Para), dexamethasone (Dex) and morphine (Morph) and to study inflammatory mediators on models of acute inflammatory pain in rats using the formalin injection test in the hind paw of rats as chemical stimulus. The obtained results showed significant modulation of pain by Thm pretreatment with a maximum at an effective dose (10 mg/kg) proved by the absence of licking and biting of the affected paw during the early and late phases of inflammation. This effect was comparable to Dex at 10 mg/kg, Para at 400 mg/kg and less than Morph at 5 mg/kg pretreatment doses. The study of anti-inflammatory targets showed that Thm pretreatment maintained plasma serotonin release at normal level compared to the negative control group (T-) and corrected the decrease in the plasma level of prostaglandins after inflammatory induction with no variation in the level of histamine in different groups. The evaluation of inflammation mediators demonstrated that the pretreatment with Thm induced the decrease in the amount of both IL-1 Beta and TNF alpha in plasma and the increase in their amount in the tissue of the injection site. The Thm has been promoted as an anti-nociceptive drug that induces modulation of inflammatory mediators.

Evaluating Outcomes and Misuse in Opioid-Dependent Chronic Pancreatitis Using a State-Mandated Monitoring System

INTRODUCTION

Patients with chronic pancreatitis (CP) often require opioids for pain control. The goal of our study was to characterize opioid use in patients with CP in a real-life practice using a state-mandated online monitoring program and to assess outcomes compared to CP patients without opioid dependency.

METHODS

CP patients seen in our Pancreas Center from 2016 to 2021 were divided into two groups-with and without chronic opioid use. Details of opioids and other controlled prescriptions were obtained by review of the Massachusetts Prescription Awareness Tool (MassPat).

RESULTS

Of the 442 CP outpatients, 216 used chronic opioids. Patients with opioid use had significantly more recurrent acute pancreatitis (76.6% vs. 52.7%), concurrent alcohol use (11.2% vs. 5.8%), tobacco use (37.8% vs. 19.7%), anxiety (22.4% vs. 16.6%), depression (43.5% vs. 23.5%) and daily pain (59.8% vs. 24.8%) (p < 0.001). They also concurrently used more benzodiazepines (43.7% vs. 12.4%), gabapentinoids (66.4% vs. 31.1%) and medical marijuana (14.9% vs. 4.19%) (p < 0.001). They had more celiac plexus blocks (22.0% vs. 6.67%), surgery (18.3% vs. 8.89%) and more hospitalizations for CP flares (3.6 vs. 1.0 visits) (p < 0.001). Less than 13% patients received opioids by means of ED visits; 81.7% patients received their prescriptions from one facility and 75% received them at regular intervals.

CONCLUSION

Opioid-dependent CP patients exhibit polypharmacy and have worse outcomes with higher resource utilization. The state-monitoring program ensures that the majority of patients receive opioids from a single facility, thereby minimizing misuse.

Impact of Ambulatory Setting for Workers' Compensation Patients Undergoing One-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion and Review of the Literature

OBJECTIVE

To compare perioperative characteristics and patient-reported outcome measures (PROMs) in workers' compensation (WC) patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in either the inpatient/outpatient setting.

METHODS

Patients with WC undergoing 1-level MIS-TLIF were included. Patients were separated into inpatient/outpatient groups and demographically propensity score matched. PROMs included visual analog scale (VAS) back/VAS leg/Oswestry Disability Index (ODI)/12-item Short Form Physical Composite Score (SF-12 PCS)/Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF) preoperatively and 6 weeks, 12 weeks, 6 months, and 1 year postoperatively. Results were compared preoperatively and postoperatively and between cohorts. Minimum clinically important difference (MCID) achievement was determined through comparison with values established in the literature.

RESULTS

A total of 216 patients were included (184 inpatient). The inpatient cohort (IC) showed worse perioperative outcomes in multiple measures (P < 0.034; all). The IC improved in all PROMs (P < 0.038; all), besides ODI at 6 weeks, SF-12 PCS at 6 weeks/6 months/1 year, and PROMIS-PF at 6 weeks. The outpatient cohort (OC) improved in VAS back at all time points and VAS leg at 6 months (P < 0.033; all). Between cohorts, the OC showed better scores with VAS leg/ODI/SF-12 PCS/PROMIS-PF at multiple time points (P < 0.031; all). Most of the IC achieved MCID, aside from ODI, whereas the OC achieved MCID in SF-12 PCS. MCID achievement between cohorts was higher in the IC at PROMIS-PF at 1 year and VAS back overall (P < 0.034; all).

CONCLUSIONS

Despite more comorbidities and worse perioperative measures, the IC showed improved PROMs from preoperative to ≥1 follow-up visit, whereas the OC had improvement with only VAS back and leg. The IC showed multiple MCID achievements, whereas the OC showed MCID in only SF-12 PCS. These findings may help guide a surgeon's decision making between inpatient/outpatient lumbar surgery in the WC population.

Effectiveness of two extended-release buprenorphine formulations during postoperative period in neonatal rats

Information on the effectiveness of a new long-lasting buprenorphine formulation, extended-release buprenorphine, in the neonatal rat is very limited. This study compares whether a high dose of extended-release buprenorphine (XR-Hi) attenuates thermal hypersensitivity for a longer period than a low dose of extended-release buprenorphine (XR-Lo) in a neonatal rat incisional pain model. Two experiments were performed. Experiment one: Male and female postnatal day-5 rat pups (n = 38) were randomly assigned to 1 of 4 treatment groups and received a subcutaneous administration of one of the following: 1) 0.9%NaCl (Saline), 0.1 mL; 2) sustained release buprenorphine (Bup-SR), 1 mg/kg; 3) XR-Lo, 0.65 mg/kg; and 4) XR-Hi, 1.3 mg/kg. Pups were anesthetized with sevoflurane in 100% O₂ and a 5 mm long skin incision was made over the left lateral thigh and underlying muscle dissected. The skin was closed with surgical tissue glue. Thermal hypersensitivity testing (using a laser diode) and clinical observations were conducted 1 hour (h) prior to surgery and subsequently after 1, 4, 8, 24, 48, 72 h of treatment. Experiment two: The plasma buprenorphine concentration level was evaluated at 1, 4, 8, 24, 48, 72 h on five-day-old rat pups. Plasma buprenorphine concentration for all treatment groups remained above the clinically effective concentration of 1 ng/mL for at least 4 h in the Bup-SR group, 8 h in XR-Lo and 24 h in XR-Hi group with no abnormal clinical observations. This study demonstrates that XR-Hi did not attenuate postoperative thermal hypersensitivity for a longer period than XR-Lo in 5-day-old rats; XR-Hi attenuated postoperative thermal hypersensitivity for up to 4 h while Bup-SR and XR-Lo for at least 8 h in this model.

Vesicular nucleotide transporter is a molecular target of eicosapentaenoic acid for neuropathic and inflammatory pain treatment

Eicosapentaenoic acid (EPA), an omega-3 (ω-3) polyunsaturated fatty acid, is an essential nutrient that exhibits antiinflammatory, neuroprotective, and cardiovascular-protective activities. Although EPA is used as a nutrient-based pharmaceutical agent or dietary supplement, its molecular target(s) is debatable. Here, we showed that EPA and its metabolites strongly and reversibly inhibit vesicular nucleotide transporter (VNUT), a key molecule for vesicular storage and release of adenosine triphosphate (ATP) in purinergic chemical transmission. In vitro analysis showed that EPA inhibits human VNUT-mediated ATP uptake at a half-maximal inhibitory concentration (IC₅₀) of 67 nM, acting as an allosteric modulator through competition with Cl^-. EPA impaired vesicular ATP release from neurons without affecting the vesicular release of other neurotransmitters. In vivo, VNUT^-/- mice showed a delay in the onset of neuropathic pain and resistance to both neuropathic and inflammatory pain. EPA potently attenuated neuropathic and inflammatory pain in wild-type mice but not in VNUT^-/- mice without affecting the basal nociception. The analgesic effect of EPA was canceled by the intrathecal injection of purinoceptor agonists and was stronger than that of existing drugs used for neuropathic pain treatment, with few side effects. Neuropathic pain impaired insulin sensitivity in previous studies, which was improved by EPA in the wild-type mice but not in the VNUT^-/- mice. Our results showed that VNUT is a molecular target of EPA that attenuates neuropathic and inflammatory pain and insulin resistance. EPA may represent a unique nutrient-based treatment and prevention strategy for neurological, immunological, and metabolic diseases by targeting purinergic chemical transmission.

Opioids and Vitamin C: Known Interactions and Potential for Redox-Signaling Crosstalk

Opioids are among the most widely used classes of pharmacologically active compounds both clinically and recreationally. Beyond their analgesic efficacy via μ opioid receptor (MOR) agonism, a prominent side effect is central respiratory depression, leading to systemic hypoxia and free radical generation. Vitamin C (ascorbic acid; AA) is an essential antioxidant vitamin and is involved in the recycling of redox cofactors associated with inflammation. While AA has been shown to reduce some of the negative side effects of opioids, the underlying mechanisms have not been explored. The present review seeks to provide a signaling framework under which MOR activation and AA may interact. AA can directly quench reactive oxygen and nitrogen species induced by opioids, yet this activity alone does not sufficiently describe observations. Downstream of MOR activation, confounding effects from AA with STAT3, HIF1α, and NF-κB have the potential to block production of antioxidant proteins such as nitric oxide synthase and superoxide dismutase. Further mechanistic research is necessary to understand the underlying signaling crosstalk of MOR activation and AA in the amelioration of the negative, potentially fatal side effects of opioids.

Patterns of Opioid Usage and Predictors of Utilization Following Endoscopic Skull Base Surgery

OBJECTIVE

Pain control is an important topic that has not been extensively studied in patients undergoing endoscopic skull base surgery (ESBS). The purpose of this study is to identify opioid requirements after ESBS and the risk factors predictive of increased use.

METHODS

This study was a retrospective review of all patients undergoing ESBS at a tertiary academic skull base surgery program between July 2018 and August 2020. The primary outcome variable was total morphine equivalent dose (MED) requirements after surgery, calculated as the sum of all morphine milligram equivalents over a 24-h period, and summated across the duration of each participant's hospital course.

RESULTS

94 patients were included in this review. Average daily MED requirements were 14.00 ± 6.79 mg. Average total MED requirements were 83.78 ± 92.99 mg during hospitalization. Average length of stay (LOS) was 5.71 ± 4.42 days, with 22 (23.4%) patients not requiring opioid use upon discharge. On multivariate analysis, female sex (β = 49.62; 95% CI [13.53, 85.71], p = 0.008), nasoseptal flap (NSF) reconstruction (β = 49.56; 95% CI [13.51, 85.61], p = 0.008) and LOS (β = 4.02; 95% CI [0.001, 8.04], p = 0.050) were independently associated with higher total MED requirements.

CONCLUSIONS

We report average total MED requirements of 83.78 mg after ESBS, with female sex, intraoperative use of an NSF, and increased LOS as predictors of higher MED use. This data indicates a subset of patients who may benefit from more aggressive pain control strategies upfront, including consideration of non-opioid, multimodal pain regimens.

LEVEL OF EVIDENCE

3 Laryngoscope, 2022.

A Practical 5-Step Approach to Nausea and Vomiting

Nausea and vomiting (N/V) are common presenting complaints in the outpatient and inpatient settings. These symptoms can be associated with high morbidity and poor quality of life, particularly in those with chronic symptoms. The clinical approach to N/V can be challenging, given the numerous possible underlying causes as well as the vast array of diagnostic and therapeutic options. In this concise review, we provide a practical 5-step approach to the clinical evaluation and treatment of N/V, suitable for application in the primary care and subspecialty settings. The 5-step approach includes (1) defining what the patient means by N/V, (2) determining whether symptoms are acute or chronic, (3) considering medication or toxin adverse effects, (4) using the patient's presentation, severity of symptoms, and physical examination findings to formulate a differential diagnosis and to guide evaluation, and (5) directing treatment on the basis of knowledge of neurotransmitters and receptors involved in the emetic pathways. We discuss the pathophysiology (neuronal pathways and neurotransmitters), differential diagnosis (medication and toxin adverse effects, neurologic causes, gastrointestinal diseases, metabolic and endocrine conditions, and psychogenic disorders), initial evaluation and risk stratification, and management and treatment options. Management of symptoms that are acute in onset or mild in severity may involve an empirical trial of antiemetics without extensive testing. In contrast, when symptoms are chronic or moderate-severe, testing for an underlying cause should be performed, and medication adverse effects, neurologic causes, gastrointestinal diseases, metabolic or endocrine conditions, and psychogenic disorders should be considered in particular.

Longitudinal Relationship between the Introduction of Medicinal Cannabis and Polypharmacy: An Australian Real-World Evidence Study

BACKGROUND

Recent studies recommend medicinal cannabis (MC) as a potential treatment for chronic pain (CP) when conventional therapies are not successful; however, data from Australia is limited. This real-world evidence study explored how the introduction of MC related to concomitant medication use over time. Long-term safety also was examined.

METHODS

Data were collected by the Emerald Clinics (a network of seven clinics located across Australia) as part of routine practice from Jan 2020 toJan 2021. Medications were classified by group: antidepressants, benzodiazepines, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and total number of medications. Adverse events (AEs) were collected at each visit and subsequently coded using the Medical Dictionary for Regulatory Activities version 23 into the system organ class (SOC) and preferred term (PT). A total of 535 patients were analyzed.

RESULTS

The most common daily oral dose was 10 mg for delta-9-tetrahydrocannabinol (THC) and 15 mg for cannabidiol (CBD). With the introduction of MC, patients' total number of medications consumed decreased over the course of one year; significant reductions in NSAIDs, benzodiazepines, and antidepressants were observed (p < .001). However, the number of prescribed opioid medications did not differ from baseline to the end of one year (p = .49). Only 6% of patients discontinued MC treatment during the study. A total of 600 AEs were reported in 310 patients during the reporting period and 97% of them were classified as nonserious. Discussion. Though observational in nature, these findings suggest MC is generally well-tolerated, consistent with the previous literature, and may reduce concomitant use of some medications. Due to study limitations, concomitant medication reductions cannot be causally attributed to MC. Nevertheless, these data underscore early signals that warrant further exploration in randomized trials.

Dopamine receptors in the anterior cingulate cortex implicate in nicotine enhanced morphine analgesia

RATIONALE

It is well known that the anterior cingulate cortex (ACC) plays an important role in acute pain perception.

OBJECTIVES

In the present study, we aimed to investigate the possible involvement of the ACC dopamine D1 and D2 receptors in nicotine plus morphine-induced analgesia.

METHODS

The ACC's of adult male Wistar rats were bilaterally cannulated by stereotaxic instrument and the tail-flick test was used to measure the thermal pain threshold.

RESULTS

The results indicated that subcutaneous (s.c.) injection of nicotine (0.3 mg/kg) potentiated the analgesic response of intraperitoneal (i.p.) administration of morphine (3 mg/kg). Systemic administration of the same doses of nicotine or morphine alone had no effect on tail-flick latency. Intra-ACC administration of apomorphine (0.3-0.9 μg/rat), the non-selective D1/D2 receptors agonist, plus ineffective doses of nicotine (0.1 mg/kg, s.c.) plus morphine (3 mg/kg, i.p) induced analgesia in rats. In addition, the analgesia induced with co-administration of nicotine and morphine was inhibited via intra-ACC administration of SCH23390 (0.5-1 μg/rat) or sulpiride (0.5-2 μg/rat), the selective antagonists of D1 or D2 receptors, respectively. The intra-ACC microinjection of the same doses of drugs alone had no effect on tail-flick latency. Cubic interpolation analysis also confirmed that activation or inactivation of the ACC D1 and D2 receptors by different doses of drugs can modulate the nicotine-morphine analgesic response.

CONCLUSIONS

The findings suggest that the ACC has an important role in acute thermal pain perception and modulates the analgesia induced by nicotine plus morphine via dopaminergic receptors.

Autogenic Training for Reducing Chronic Pain: a Systematic Review and Meta-analysis of Randomized Controlled Trials

Background

Autogenic training (AT) is frequently used as therapeutic approach in multimodal pain therapy. The aim of this systematic review and meta-analysis is to investigate the efficacy of AT in individuals suffering from chronic pain in comparison to passive and active control groups.

Methods

A comprehensive literature search in Medline, Web of Science, PsycInfo, and PubPsych and manual searches (last search April 7, 2021) were conducted to locate randomized controlled trials (RCTs). Treatment guidelines and references of relevant articles and previous reviews were checked. ProQuest Dissertations and Theses Full Text database, DART-Europe E-theses Portal, Networked Digital Library of Theses and Dissertations (NDLTD), and the Theses Database of the German National Library were screened to identify any unpublished material.

Results

A total of 13 eligible studies (k = 15 comparisons) including 576 participants were identified. Random-effects meta-analyses revealed a significantly positive, moderate effect of AT on the primary outcome pain compared to passive control groups (g = 0.58, 95% CI [0.36; 0.79], k = 9, I² = 0%). In comparison with other psychological interventions, no difference was found (g = − 0.05, 95% CI [− 0.30; 0.20], k = 6, I² = 0%). Sensitivity analyses proved the robustness of findings. Overall risk-of-bias judgment was ‘some concerns’ in the majority of studies.

Conclusions

Beneficial effects of AT on pain reduction were demonstrated, but findings are prone to bias. Furthermore, high methodological quality RCTs are needed to strengthen the promising evidence of AT for individuals with chronic pain.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12529-021-10038-6.

Opioid-Related Side Effects and Management

The following areas will be discussed in relation to opioid-related side effects and approaches to their management in the cancer patient.

Ultrasound-guided erector spinae plane block for postoperative analgesia in laparoscopic liver resection: A prospective, randomised controlled, patient and observer-blinded study

BACKGROUND

Erector spinae plane block (ESPB) has been reported to manage postoperative pain effectively after various types of surgery. However, there has been a lack of study on the effect of ESPB after liver resection.

OBJECTIVES

To investigate the analgesic effects of ESPB on pain control after laparoscopic liver resection compared with conventional pain management.

DESIGN

Prospective, randomised controlled study.

SETTING

A single tertiary care centre from February 2019 to February 2020.

PATIENTS

A total of 70 patients scheduled to undergo laparoscopic liver resection.

INTERVENTIONS

In the control group (n = 35), no procedure was performed. In the ESPB group (n = 35), ESPB was performed after induction of general anaesthesia. A total of 40 ml of ropivacaine 0.5% was injected at the T9 level bilaterally. After surgery, intravenous fentanyl patient-controlled analgesia was initiated. Fentanyl and hydromorphone were administered as rescue analgesics.

MAIN OUTCOME MEASURES

The primary outcome was the cumulative postoperative opioid consumption at 24 h (morphine equivalent). The secondary outcomes were rescue opioid (fentanyl) dose in the postanaesthesia care unit (PACU) and pain severity at 1, 6, 12, 24, 48 and 72 h, assessed using a numerical rating scale (NRS) score.

RESULTS

The median [IQR] postoperative opioid consumption during 24 hours following surgery was 48.2 [17.1] mg in the control group and 45.5 [35.8] mg in the ESPB group (median difference, 4.2 mg; 95% CI, -4.2 to 13.3 mg; P = 0.259). Conversely, rescue opioid in PACU was 5.3 [5.0] mg in the control group and 3.0 [1.5] mg in the ESPB group (median difference, 2.5 mg; 95% CI, 1.0 to 5.0 mg; P < 0.001). There was no significant difference in NRS scores point between the groups at any time.

CONCLUSION

ESPB does not provide analgesic effect within 24 h after laparoscopic liver resection.

TRIAL REGISTRATION

Clinical Trial Registry of Korea (https://cris.nih.go.kr.), identifier: KCT0003549).

Characteristics of ambulatory spine care visits in the United States, 2009-2016

BACKGROUND

Back pain is a leading reason for seeking care in the United States (US), and is a major cause of morbidity.

OBJECTIVE

To analyze demographic, patient, and visit characteristics of adult ambulatory spine clinic visits in the United States from 2009-2016.

METHODS

Data from the National Ambulatory Medical Care Survey from 2009-2016 were used and were sample weighted.

RESULTS

Most patients presenting for ambulatory spine care were 45-64 years (45%), were most commonly female (56.8%), and private insurance (45%) and Medicare (26%) were most common payors. The percentage of visits for spine care done at a primary care setting was 50.1% in 2009-2010 and 48.3% in 2014-2015. Approximately 15.5% were seen in orthopedic surgery clinics in 2009-2010 and 7.3% in 2015-2016. MRI was utilized in 11.7% in 2009-2010 and 11.0% in 2015-2016. Physical therapy was prescribed in 13.2% and narcotic analgesic medications were prescribed in 36.2% of patients in 2015-2016.

CONCLUSIONS

MRI was used more frequently than guidelines recommended, and physical therapy was less frequently utilized despite evidence. A relatively high use of opiates in treatment of back pain was reported and is concerning. Although back pain represents a substantial public health burden in the United States, the delivery of care is not evidence-based.

Prophylactic Administration of Diphenhydramine/Acetaminophen and Ondansetron Reduced Postoperative Nausea and Vomiting and Pain Following Laparoscopic Sleeve Gastrectomy: a Randomized Controlled Trial

PURPOSE

Postoperative nausea and vomiting (PONV) and pain following bariatric surgery are problematic and affect the outcome of patients. Intraoperative multimodal antiemetic prophylaxis is essential to improve postoperative outcomes. This study investigated the effect of adding diphenhydramine to acetaminophen and ondansetron in reducing postoperative nausea and vomiting and pain following laparoscopic sleeve gastrectomy (LSG).

MATERIALS AND METHODS

Eighty-two patients scheduled for LSG were assigned to receive a single preinduction dose of diphenhydramine 0.4 mg/kg VI (D group) in addition to acetaminophen 1g and ondansetron 4 mg IV at the end of surgery and just acetaminophen 1 g and ondansetron 4 mg IV (C group) in a randomized, double-blind trial. PONV was assessed in recovery and 24 hours after surgery in the ward. Postoperative pain, analgesic requirements, and patients' level of sedation were also assessed.

RESULTS

The PONV rates in the recovery of the D group and the C group were 30% and 56% (P = .001). It also had a more significant reduction in the D group than in the C group in the first 24 h after surgery (40% vs. 66%). The severity of pain score and level of sedation and analgesic requirements was significantly reduced in this period in the D group.

CONCLUSION

Prophylactic diphenhydramine 0.4 mg/kg at the induction of general anesthesia in combination with acetaminophen 1 g and ondansetron 4 mg at the end of surgery reduced the incidence of PONV and postoperative severity of pain in laparoscopic sleeve gastrectomy.

Evaluation of analgesic efficacy and opioid sparing effect of pregabalin after arthroscopic rotator cuff repair surgery: A retrospective cohort study

BACKGROUND

Considering the adverse effects of opioids, it is essential to minimize their consumption for postoperative pain control. Studies have reported the opioid sparing effects of pregabalin, with conflicting results. Evidence for administering pregabalin in a multimodal regimen after arthroscopic rotator cuff repair surgery is limited.

METHODS

A total of 64 patients who underwent arthroscopic rotator cuff repair were enrolled in the cohort, and their data were retrospectively analyzed to evaluate the ability of pregabalin for postoperative analgesia and opioid sparing. The pregabalin group (n = 32) received additional pregabalin 75 mg for 2 weeks from the day before the surgery with the standard pain medications; in contrast, the control group (n = 32) was prescribed the standard pain medications alone. The total volume of patient-controlled anesthesia, doses of oral oxycodone and intravenous morphine as rescue analgesics, number of adverse events, and patient satisfaction based on the numeric rating scale (0-10) were assessed. Further, we used the visual analog scale for evaluating pain and function for 6 months in each group.

RESULTS

Total patient-controlled anesthesia volume, number of patient-controlled anesthesia attempts on the day of surgery, and total oral oxycodone consumption were significantly lower in the pregabalin group. Visual analog scale scores for pain and function showed no significant differences. Although the total number of adverse effects (nausea, vomiting, dizziness, dry mouth, urinary retention, itching sense, or constipation) was higher in the pregabalin group than in the control group, the difference was not statistically significant.

CONCLUSION

Our multimodal regimen with pregabalin significantly reduced opioid consumption with similar adverse effects. However, there was no significant difference in the pain score. We recommend pregabalin as an additional analgesic for arthroscopic rotator cuff repairs, especially for medium to large sized tears.

A retrospective study comparing analgesic efficacy of ultrasound-guided serratus anterior plane block versus intravenous fentanyl infusion in patients with multiple rib fractures

BACKGROUND AND AIMS

Inadequately managed pain due to multiple rib fractures (MRFs) can lead to atelectasis, pneumonia, prolonged ICU stay thereby leads to significant morbidity, morbidity and cost of treatment. Opioids, non-steroidal anti-inflammatory drugs and regional anaesthesia techniques like thoracic epidural or paravertebral blocks, intercostal nerve blocks are used to manage pain. Serratus anterior plane block (SAPB) is an ultrasound (US) guided interfascial plane block which has been used in managing pain due to MRFs. In this retrospective study, we compared analgesic efficacy and 24 hr fentanyl consumption in patients with MRFs who were managed with continuous SAPB versus patients who were managed with fentanyl infusion alone.

MATERIAL AND METHODS

After Institutional Ethics Committee approval, we retrospectively collected data of 72 patients (38 in SAPB group and 34 in fentanyl group). Demographic data, VAS scores and 24 hrs fentanyl consumption was analysed in both groups.

RESULTS

There were statistically significant lower pain scores in patients of SAPB group when compared to that of fentanyl group (p=0.001) and in 24 hrs fentanyl consumption in patients who received continuous SAPB versus that in fentanyl group(p=0.001). No complications were observed in patients who received US guided SAPB.

CONCLUSION

US guided SAPB is an opioid sparing, effective interfascial plane block which is safe and should be considered early in all patients who sustain MRFs. Continuous SAPB by placing a catheter can provide pain relief for longer duration, facilitate early mobilization, physiotherapy and early ICU discharge.

Preclinical Assessment of the Analgesic Pharmacology of NKTR-181 in Rodents

OBJECTIVE

Pharmacological evaluation of the mu-opioid receptor (MOR) agonist properties of NKTR-181 in rodent models.

METHODS

Graded noxious stimulus intensities were used in rats to establish the antinociceptive potency and efficacy of NKTR-181 relative to morphine, fentanyl, and oxycodone. Characteristics of MOR agonist actions, as measured by antinociceptive tolerance and cross-tolerance, as well as opioid-induced hyperalgesia (OIH) and naloxone-precipitated withdrawal in NKTR-181- and morphine-dependent in mice, were compared.

RESULTS

NKTR-181 showed dose- and time-related antinociception with similar maximal effects to morphine in the rat and mouse hot-water tail-flick test. No sex or species differences were observed in NKTR-181 or morphine antinociception. Rats treated with NKTR-181 and morphine exhibited decreases in both potency and maximal efficacy as nociceptive stimulus intensity was increased from a water temperature of 50 °C to 54 °C. Evaluation of antinociception at a high stimulus intensity revealed that oxycodone and fentanyl exhibited greater efficacy than either NKTR-181 or morphine. The relative potency difference between NKTR-181 and morphine across all tail-flick studies was determined to be 7.6-fold (90% confidence interval, 2.6, 21.5). The peak antinociceptive effect of NKTR-181 was delayed compared to that of the other opioids and cumulative drug effects were not observed. Repeated treatment with escalating, approximately equi-analgesic doses of NKTR-181 or morphine, produced antinociceptive tolerance and cross-tolerance. Under these pharmacological conditions, OIH and naloxone-precipitated physical dependence were similar for NKTR-181 and morphine.

CONCLUSIONS

NKTR-181 had a slower onset, but similar efficacy, to morphine in the models studied supporting reduced abuse potential while maintaining analgesic effect in comparison with current opioids.

Topical Fixed-Dose Combinations: A Way of Progress for Pain Management?

Pain, a severe public health problem, can affect patient quality of life when inadequately controlled. Considering that pain pathophysiological mechanisms are complex, combining active pharmaceutical ingredients (APIs) with multiple and synergistic mechanisms of action represents a potentially more effective therapeutic approach than conventional monotherapy treatments. In turn, topical drug delivery has clear advantages over other routes of administration, such as high levels of efficacy, better safety profile and great patient compliance. In this context, the combination of two or more APIs in a single dosage form - fixed-dose combination product (FDC) - for topical administration may represent a promising therapeutic option in the field of pain management. Considering the above mentioned, the purpose of this manuscript is to address an overview of some general aspects regarding pain management and FDCs, as well as the regulatory environment that has to be taken into consideration during their development. Special emphasis will be given to fixed-dose combinations for topical administration with analgesic and/or anti-inflammatory activity. Market drivers of the topical FDC currently approved are ultimately pointed out, and new opportunities in pain management highlighted.

Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems

Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, and corresponding receptors, as well as intracellular emetic signaling pathways involved in the processes of nausea and vomiting in diverse animal models as well as humans. While blockade of emetic receptors in the prevention of vomiting is fairly well understood, the potential of new classes of antiemetics altering postreceptor signal transduction mechanisms is currently evolving, which is also reviewed. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide potential answers.

Inducing positive emotions to reduce chronic pain: a randomized controlled trial of positive psychology exercises

PURPOSE

Positive emotions have been found to be analgesic and can be induced by positive psychology exercises. This study tested if positive psychology exercises provide beneficial effects on pain, responses to pain, physical (pain interference), and emotional function.

METHODS

Randomized parallel-group controlled single-blinded superiority-trial including community-dwelling individuals with chronic pain secondary to spinal cord injury. Participants in the intervention group were instructed to practice 4 personalized positive psychology exercises for 8 weeks. Participants in the control group were asked to be mindful and write about current life events.

RESULTS

108 (64%) completed the study. At post-treatment, the intervention participants reported significant reductions in pain intensity and improvements in pain catastrophizing and pain control, relative to baseline. Both groups reported significant decreases in pain interference and negative emotions. Significant between-group differences emerged for pain intensity at post-treatment. At 3-months follow-up, improvements maintained for the intervention group and improvements in positive emotions reached statistical significance. Between-group differences were identified for pain intensity at post-treatment.

CONCLUSION

Positive psychology exercises represent a potential effective complementary treatment that result in benefits on pain which can be readily implemented into daily living. Trials designed with an inactive control condition should be conducted to further address efficacy.

TRIAL REGISTRATION

Swiss ethics committee (EKNZ 2014-317)/clinicaltrials.gov (NCT02459028) Registration date: Ethics approval 25.10.2014/Study start date: May 2015 URL of the record: https://clinicaltrials.gov/ct2/show/NCT02459028?term=NCT02459028&cntry=CH&draw=2&rank=1IMPLICATIONS FOR REHABILITATIONPain engenders negative emotions (e.g., fear, anger, sadness) which can negatively affect psychological, social, and physical function.Positive emotions have been found to be analgesic and can be induced by practicing positive psychology exercises.The findings of the current randomized controlled trial provide support for practicing positive psychology exercises (beyond the effects of pain medication intake), in particular on the reduction of pain intensity, but also in improving pain catastrophizing and pain control.The majority of the positive psychology exercises are brief and self-administered positive activities that have no known negative side effects nor financial cost, can be tailored to a person's preferences in activities and can be readily implemented into daily living with chronic pain, complementing standard treatment of pain.

Recent advances in the opioid mu receptor based pharmacotherapy for rheumatoid arthritis

INTRODUCTION

Opioids are used for severe forms of acute and cancer pain. Over the last years, their potential use in patients with noncancer pain such as those with rheumatoid arthritis (RA) has been postulated. A recent population-based comparative study showed that chronic opioid use was 12% vs. 4% among RA and non-RA patients, respectively. Another study showed an increase from 7.4% to 16.9% (2002 to 2015). In general, there has been an increasing tendency to use opioids in recent years.

AREAS COVERED

The authors have performed an extensive literature search using PubMed for articles including noncancer pain and the use of the mu opioid receptor (MOR) agonists in patients with RA.

EXPERT OPINION

Data is not sufficient to support opioid use for the treatment of chronic pain in patients with RA. Data is scarce and inconclusive. Rheumatologists should think and ponder the question: Why is this patient in pain? Differential diagnosis should include a disease flare, degenerative changes of the musculoskeletal system, and fibromyalgia. And while there are new strategies for opioid administration currently being researched, unfortunately, they are far from being applied to human subjects in the everyday clinical setting, and are still being evaluated at an experimental level. CNS: Central nervous system; DORs: delta opioid receptor agonists; GI: Gastrointestinal; GPCRs: G protein-coupled receptors; IL: Interleukin; JAK: Janus kinase; KORs: kappa opioid receptor agonists; MCPs: Metacarpophalangeal joints; MORs: Mu opioid receptor agonists; MTPs: Metatarsophalangeal joints; NSAIDs: Non-steroidal anti-inflammatory drugsOA: Osteoarthritis; ORs: Opioid receptors; PD: Pharmacodynamic; PIPs: Proximal interphalangeal joints; PK: Pharmacokinetic; PNS: Peripheral nervous system; RA: Rheumatoid arthritis; RGS: Regulator of G protein signaling; SSRIs: Selective serotonin reuptake inhibitors; TNF: Tumor necrosis factor.

Opioid-Induced Reductions in Gait Variability in Healthy Volunteers and Individuals with Knee Osteoarthritis

OBJECTIVE

To investigate differences in gait variability induced by two different single-dose opioid formulations and an inert placebo in healthy volunteers and knee osteoarthritis patients.

DESIGN

Experimental, randomized, double-blinded, crossover study of inert placebo (calcium tablets), 50 mg of tapentadol, and 100 mg of tramadol.

SETTING

Laboratory setting.

SUBJECTS

Healthy volunteers and knee osteoarthritis patients.

METHODS

At three visits, separated by seven days, one tablet was administered per visit according to the randomization code. At each visit, a baseline measurement was done before tablet administration, after which hourly measurements were performed for six hours, yielding a total of seven measurements per visit. Gait variability was measured by three-dimensional gait analysis, recorded during six minutes of continuous treadmill walking at self-selected speed. One hundred seventy gait cycles were identified from detection of clear events of the knee joint angle trajectories. Gait variability was assessed as average standard deviations over a gait cycle of the sacrum displacements and accelerations; sagittal plane ankle, knee, and hip joint angles; step widths; and stride times.

RESULTS

Twenty-four opioid-naïve and neurologically intact participants (12 healthy volunteers and 12 knee osteoarthritis patients) were included and completed the experiment. Tapentadol reduced the variability of sacrum displacements and accelerations compared with placebo and tramadol. There were no differences between experimental conditions regarding the variability in lower-extremity joint angle variability, step widths, or stride times.

CONCLUSIONS

In opioid-naïve and neurologically intact individuals, tapentadol seems to reduce movement variability during treadmill walking, compared with placebo and tramadol. This can be interpreted as a loss of adaptability that might increase the risk of falling if the system is perturbed.

Recent advances with 5-HT3 modulators for neuropsychiatric and gastrointestinal disorders

Serotonin (5-hydroxytryptophan [5-HT]) is a biologically active amine expressed in platelets, in gastrointestinal (GI) cells and, to a lesser extent, in the central nervous system (CNS). This biogenic compound acts through the activation of seven 5-HT receptors (5-HT_1-7 Rs). The 5-HT₃ R is a ligand-gated ion channel belonging to the Cys-loop receptor family. There is a wide variety of 5-HT₃ R modulators, but only receptor antagonists (known as setrons) have been used clinically for chemotherapy-induced nausea and vomiting and irritable bowel syndrome treatment. However, since the discovery of the setrons in the mid-1980s, a large number of studies have been published exploring new potential applications due their potency in the CNS and mild side effects. The results of these studies have revealed new potential applications, including the treatment of neuropsychiatric disorders such as schizophrenia, depression, anxiety, and drug abuse. In this review, we provide information related to therapeutic potential of 5-HT₃ R antagonists on GI and neuropsychiatric disorders. The major attention is paid to the structure, function, and pharmacology of novel 5-HT₃ R modulators developed over the past 10 years.

Preventive effects of naldemedine, peripherally acting μ-opioid receptor antagonist, on morphine-induced nausea and vomiting in ferrets

AIMS

Naldemedine is a peripherally acting μ-opioid receptor antagonists (PAMORAs) indicated for the treatment of opioid-induced constipation (OIC). We investigated the preventive effect of naldemedine on morphine-induced nausea and vomiting in ferrets and conducted a pharmacokinetic/pharmacodynamic (PK/PD) analysis.

MAIN METHODS

The antiemetic effect of naldemedine was evaluated as the frequency and time of retching (rhythmic abdominal contractile motion) and vomiting (throwing up vomit or similar reactions) caused by morphine in ferrets. After a single oral administration of naldemedine to ferrets, the plasma concentrations of naldemedine and morphine were measured by liquid chromatography-tandem mass spectrometry.

KEY FINDINGS

Naldemedine showed a potent and dose-dependent anti-emetic effects against morphine-induced emetic responses, for up to 6 h. The dose of naldemedine that produced half the maximal effect (ED₅₀) value for anti-emetic effect of naldemedine in the morphine-treated ferrets was 0.033 mg/kg. The PK/PD analysis revealed that the antiemetic effect was related to the plasma naldemedine concentration, with a half maximal effective concentration that produces half the maximal effect (EC₅₀) of 3.51 ng/mL. The plasma concentration producing an antiemetic effect was almost 200-fold lower than that inducing an anti-analgesic effect in rats.

SIGNIFICANCE

Naldemedine showed potent inhibition of morphine-induced vomiting for up to 6 h after dosing. These data suggest that naldemedine possesses antiemetic properties and could be effective against opioid-induced nausea and vomiting (OINV).

Should Antiemetics be Given Prophylactically with Intravenous Opioids While Treating Acute Pain in the Emergency Department?: Clinical Practice Paper Approved by American Academy of Emergency Medicine Clinical Guidelines Committee

BACKGROUND

It is common practice for emergency physicians to give parenteral opioids for acute pain, however, some treating physicians have concerns that using parenteral opioids can lead to nausea and vomiting when used alone. Therefore, antiemetics are often given prophylactically with opioids for nausea and vomiting in the emergency department (ED). This systematic review evaluates the use of prophylactic antiemetics with parenteral opioids for the treatment of acute pain in the ED.

METHODS

A 10-year literature search using keywords was performed in PubMed for English-language human studies. Abstracts were screened to identify high-quality studies, which then underwent a more rigorous structured review. The recommendations are made based on the literature review.

RESULTS

Eight articles met criteria for structured review and citation in this article. These include one review article, two randomized controlled trials, three prospective observational trials, one retrospective study, and one pre- and post-intervention trial.

CONCLUSIONS

Based on the literature review, routine use of prophylactic antiemetics are not indicated with administration of parenteral opioids for treatment of acute pain in the ED, as nausea and vomiting are infrequent side effects. The recent literature clearly demonstrates that there are potential undesirable side effects from the use of antiemetics when using opioids. However, one subgroup of patients, those with a known history of nausea and vomiting after opioid use or a history of travel sickness, may benefit from the use of prophylactic antiemetic when being treated with parenteral opioids.

Local drug delivery from surgical thread for area-specific anesthesia

The application of surgical suture-thread and the systemic analgesics regimens for pain control in the postoperative surgery remain the criterion standard. However, these medications have daunting adverse effects on the body's innate pain management system. To address this issue, we have developed a local analgesic-loaded suture system which could be efficiently used for surgical repair with localized sedation effect. The drug-loaded conventional suture has modified by adhesive poly-dopamine coating with the local anesthetic lidocaine. The surface modifications have been ascertained by FE-SEM imaging. The tensile strength of suture ensures required elasticity to use in surgical skin closure. In vitro drug release and the in vivo local analgesia was achieved one day after surgery and persisted approximately for one week in 80% of treated animals. Our pre-clinical results suggest that drug-loaded surgical thread may be an effective strategy for improving the overall outcome.

Comparison of Sufentanil- and Fentanyl-based Intravenous Patient-controlled Analgesia on Postoperative Nausea and Vomiting after Laparoscopic Nephrectomy: A Prospective, Double-blind, Randomized-controlled Trial

Background: The incidence of postoperative nausea and vomiting (PONV) remains high. The effects of sufentanil for PONV is not firmly confirmed. The aim of this study was to compare the effect of sufentanil- and fentanyl-based intravenous patient-controlled analgesia (IV-PCA) on the incidence of PONV after laparoscopic nephrectomy. Methods: Eighty-six patients were randomly allocated to receive either the sufentanil (n =43) or fentanyl (n =43). IV-PCA was prepared using either sufentanil 3 µg/kg or fentanyl 20 µg/kg, ramosetron 0.3 mg, and ketorolac 120 mg. The primary outcome of was the incidence of PONV during 24 h after post anesthesia care unit (PACU) discharge. The secondary outcomes were the modified Rhodes index and patient satisfaction scores at 24 h after PACU discharge, need for rescue antiemetics, pain score, need for additional analgesics, and cumulative consumption of IV-PCA Results: The incidence of PONV was comparable between the sufentanil and fentanyl groups (64.3% vs. 65%, p = 0.946; respectively). The number of patients who required antiemetics (p = 0.946) and the modified Rhodes index at 24 h after post-anesthesia care unit discharge (p = 0.668) were also comparable in both groups. No significant differences were found in the secondary outcomes, including the analgesic profiles and adverse events between the groups. Conclusions: In conclusion, sufentanil- and fentanyl-based IV-PCA showed similar incidence of PONV with comparable analgesic effects after laparoscopic nephrectomy. Based on these results, we suggest that sufentanil and fentanyl may provide comparable effects for IV-PCA after laparoscopic nephrectomy.

Cross-talk between Human Spinal Cord μ-opioid Receptor 1Y Isoform and Gastrin-releasing Peptide Receptor Mediates Opioid-induced Scratching Behavior

BACKGROUND

Although spinal opioids are safe and effective, pruritus is common and distressing. The authors previously demonstrated in mouse spinal cord that interactions between μ-opioid receptor isoform 1D and gastrin releasing peptide receptor mediate morphine-induced scratch. The C-terminal of 1D inhibits morphine-induced scratch without affecting analgesia. The authors hypothesize that human spinal cord also contains itch-specific μ-opioid receptor isoforms which interact with gastrin releasing peptide receptor.

METHODS

Reverse transcription polymerase chain reaction was performed on human spinal cord complimentary DNA from two human cadavers. Calcium responses to morphine (1 μM) were examined using calcium imaging microscopy on human cells (HEK293) coexpressing gastrin releasing peptide receptor and different human μ-opioid receptor isoforms. The authors assessed morphine-induced scratching behavior and thermal analgesia in mice following intrathecal injection of morphine (0.3 nmol) and a transactivator of transcription peptide designed from C-terminal sequences of 1Y isoform (0, 0.1, and 0.4 nmol).

RESULTS

The authors demonstrated 1Y expression in the spinal cord dorsal horn. Morphine administration evoked a calcium response (mean ± SD) (57 ± 13 nM) in cells coexpressing both gastrin releasing peptide receptor and the 1Y isomer. This was blocked by 10 μM naltrexone (0.7 ± 0.4 nM; P < 0.0001), 1 μM gastrin-releasing peptide receptor antagonist (3 ± 2 nM; P < 0.0001), or 200 μM 1Y-peptide (2 + 2 nM; P < 0.0001). In mice, 0.4 nmol 1Y-peptide significantly attenuated morphine-induced scratching behaviors (scratching bouts, vehicle vs. 1Y-peptide) (92 ± 31 vs. 38 ± 29; P = 0.011; n = 6 to 7 mice per group), without affecting morphine antinociception in warm water tail immersion test (% of maximum possible effect) (70 ± 21 vs. 67 ± 22; P = 0.80; n = 6 mice per group).

CONCLUSIONS

Human μ-opioid receptor 1Y isomer is a C-terminal splicing variant of Oprm1 gene identified in human spinal cord. Cross-talk between 1Y and gastrin releasing peptide receptor is required for mediating opioid-induced pruritus. Disrupting the cross talk may have implications for therapeutic uncoupling of desired analgesic effects from side effects of opioids.