New directions in the treatment of opioid withdrawal

Rebound activation of 5-HT neurons following SSRI discontinuation

Cessation of therapy with a selective serotonin (5-HT) reuptake inhibitor (SSRI) is often associated with an early onset and disabling discontinuation syndrome, the mechanism of which is surprisingly little investigated. Here we determined the effect on 5-HT neurochemistry of discontinuation from the SSRI paroxetine. Paroxetine was administered repeatedly to mice (once daily, 12 days versus saline controls) and then either continued or discontinued for up to 5 days. Whereas brain tissue levels of 5-HT and/or its metabolite 5-HIAA tended to decrease during continuous paroxetine, levels increased above controls after discontinuation, notably in hippocampus. In microdialysis experiments continuous paroxetine elevated hippocampal extracellular 5-HT and this effect fell to saline control levels on discontinuation. However, depolarisation (high potassium)-evoked 5-HT release was reduced by continuous paroxetine but increased above controls post-discontinuation. Extracellular hippocampal 5-HIAA also decreased during continuous paroxetine and increased above controls post-discontinuation. Next, immunohistochemistry experiments found that paroxetine discontinuation increased c-Fos expression in midbrain 5-HT (TPH2 positive) neurons, adding further evidence for a hyperexcitable 5-HT system. The latter effect was recapitulated by 5-HT1A receptor antagonist administration although gene expression analysis could not confirm altered expression of 5-HT1A autoreceptors following paroxetine discontinuation. Finally, in behavioural experiments paroxetine discontinuation increased anxiety-like behaviour, which partially correlated in time with the measures of increased 5-HT function. In summary, this study reports evidence that, across a range of experiments, SSRI discontinuation triggers a rebound activation of 5-HT neurons. This effect is reminiscent of neural changes associated with various psychotropic drug withdrawal states, suggesting a common unifying mechanism.

Effects of inhaled low-concentration xenon gas on naltrexone-precipitated withdrawal symptoms in morphine-dependent mice

BACKGROUND

Opioid withdrawal symptoms (OWS) are highly aversive and prompt unprescribed opioid use, which increases morbidity, mortality, and, among individuals being treated for opioid use disorder (OUD), recurrence. OWS are driven by sympathetic nervous system (SNS) hyperactivity that occurs when blood opioid levels wane. We tested whether brief inhalation of xenon gas, which inhibits SNS activity and is used clinically for anesthesia and diagnostic imaging, attenuates naltrexone-precipitated withdrawal-like signs in morphine-dependent mice.

METHODS

Adult CD-1 mice were implanted with morphine sulfate-loaded (60 mg/ml) minipumps and maintained for 6 days to establish morphine dependence. On day 7, mice were given subcutaneous naltrexone (0.3 mg/kg) and placed in a sealed exposure chamber containing either 21% oxygen/balance nitrogen (controls) or 21% oxygen/added xenon peaking at 30%/balance nitrogen. After 10 minutes, mice were transferred to observation chambers and videorecorded for 45 minutes. Videos were scored in a blind manner for morphine withdrawal behaviors. Data were analyzed using 2-way ANOVAs testing for treatment and sex effects.

RESULTS AND CONCLUSIONS

Xenon-exposed mice exhibited fewer jumps (P = 0.010) and jumping suppression was detectible within the first 10-minute video segment, but no sex differences were detected. Brief inhalation of low concentration xenon rapidly and substantially attenuated naltrexone-precipitated jumping in morphine-dependent mice, suggesting that it can inhibit OWS. If xenon effects translate to humans with OUD, xenon inhalation may be effective for reducing OWS, unprescribed opioid use, and for easing OUD treatment initiation, which could help lower excess morbidity and mortality associated with OUD.

Clinical prediction model for interdisciplinary biopsychosocial rehabilitation in osteoarthritis patients

BACKGROUND

Osteoarthritis (OA) is a heterogenous condition, in which different subgroups are present. Individualized interdisciplinary multimodal pain treatments (IMPT) based on the biopsychosocial model have resulted in positive improvement of pain, health and disability in OA patients. Moreover, predictive factors for treatment success of IMPT in different musculoskeletal pain populations have been examined, but a clinical prediction model which informs whether an OA patient is expected to benefit or not from IMPT is currently lacking.

AIM

The aim was to develop and internally validate a clinical prediction model to inform patient-tailored care based on identified predictors for positive or negative outcomes of IMPT in patients with OA.

DESIGN

Longitudinal prospective cohort study.

SETTING

Center for Integral Rehabilitation at six locations in the Netherlands.

POPULATION

Chronic OA patients.

METHODS

Data in this study were collected during January 2019 until January 2022. Participants underwent a 10-week IMPT program based on the biopsychosocial model. Treatment success was defined by a minimal decrease from baseline of 9 points on the Pain Disability Index (PDI). Candidate predictors were selected by experts in IMPT and literature review. Backward logistic regression analysis was performed to develop the clinical predication model and bootstrap validation was performed for internal validation.

RESULTS

Overall, 599 OA patients were included, of which 324 experienced treatment success. Thirty-four variables were identified as possible predictors for good IMPT outcome. Age, gender, number of pain locations, PDI baseline score, maximal pain severity, use of pain medication and alcohol, work ability, brief illness perceptions questionnaire subscales timeline, consequences, identity and treatment control, pain catastrophizing scale and self-efficacy questionnaire score were found as predictors for treatment success. The internally validated model has an acceptable discriminative power of 0.71.

CONCLUSIONS

This study reports a specific clinical prediction model for good outcome of IMPT in patients with OA. The internally validated model has an acceptable discriminative power of 0.71.

CLINICAL REHABILITATION IMPACT

After external validation, this model could be used to develop a clinically useful decision tool.

Novel Use of Clonidine Patch to Treat Tizanidine Withdrawal

Tizanidine is commonly prescribed for muscle spasticity and pain. Yet, withdrawal is rarely reported. Tizanidine stimulates presynaptic α-2 adrenergic and imidazoline receptors decreasing norepinephrine release. Abrupt cessation can cause withdrawal. Current treatment strategies include tapering oral tizanidine or substituting oral clonidine. A 52-year-old male with a history of hypertension, diabetes, coronary artery disease, and chronic back pain presented with altered mental status, agitation, hypertensive emergency (blood pressure: 250/145 mmHg), and tachycardia. The patient had been prescribed tizanidine for chronic back pain for two years and had recently run out with suspicion of misuse. Tizanidine withdrawal was diagnosed, and he improved with 0.1 mg oral clonidine three times daily weaned over five days while hospitalized. One month later the patient was admitted for persistent hypertension, tachycardia, diaphoresis, and anxiety. Alpha-2 agonist withdrawal was again diagnosed. Utilizing a clonidine patch taper may offer a reasonable approach in patients with tizanidine withdrawal.

Cold nociception as a measure of hyperalgesia during spontaneous heroin withdrawal in mice

Opioids are powerful analgesic drugs that are used clinically to treat pain. However, chronic opioid use causes compensatory neuroadaptations that result in greater pain sensitivity during withdrawal, known as opioid withdrawal-induced hyperalgesia (OWIH). Cold nociception tests are commonly used in humans, but preclinical studies often use mechanical and heat stimuli to measure OWIH. Thus, further characterization of cold nociception stimuli is needed in preclinical models. We assessed three cold nociception tests-thermal gradient ring (5-30 °C, 5-50 °C, 15-40 °C, and 25-50 °C), dynamic cold plate (4 °C to -1 °C at -1 °C/min, -1 °C to 4 °C at +1 °C/min), and stable cold plate (10 °C, 6 °C, and 2 °C)-to measure hyperalgesia in a mouse protocol of heroin dependence. On the thermal gradient ring, mice in the heroin withdrawal group preferred warmer temperatures, and the results depended on the ring's temperature range. On the dynamic cold plate, heroin withdrawal increased the number of nociceptive responses, with a temperature ramp from 4 °C to -1 °C yielding the largest response. On the stable cold plate, heroin withdrawal increased the number of nociceptive responses, and a plate temperature of 2 °C yielded the most significant increase in responses. Among the three tests, the stable cold plate elicited the most robust change in behavior between heroin-dependent and nondependent mice and had the highest throughput. To pharmacologically characterize the stable cold plate test, we used μ-opioid and non-opioid receptor-targeting drugs that have been previously shown to reverse OWIH in mechanical and heat nociception assays. The full μ-opioid receptor agonist methadone and μ-opioid receptor partial agonist buprenorphine decreased OWIH, whereas the preferential μ-opioid receptor antagonist naltrexone increased OWIH. Two N-methyl-d-aspartate receptor antagonists (ketamine, MK-801), a corticotropin-releasing factor 1 receptor antagonist (R121919), a β2-adrenergic receptor antagonist (butoxamine), an α2-adrenergic receptor agonist (lofexidine), and a 5-hydroxytryptamine-3 receptor antagonist (ondansetron) had no effect on OWIH. These data demonstrate that the stable cold plate at 2 °C yields a robust, reliable, and concise measure of OWIH that is sensitive to opioid agonists.

Management of Critically Ill Patients Receiving Medications for Opioid Use Disorder

TOPIC IMPORTANCE

Critical care clinicians are likely to see an increasing number of patients admitted to the ICU who are receiving US Food and Drug Administration-approved medications for opioid use disorder (MOUDs) given the well-documented benefits of these agents. Oral methadone, multiple formulations of buprenorphine, and extended-release naltrexone are the three types of MOUD most likely to be encountered by ICU clinicians; however, these drugs vary with respect to formulations, pharmacokinetics, and adverse effects.

REVIEW FINDINGS

No published clinical practice guidelines or consensus statements are available to guide decision-making in patients admitted to the ICU setting who are receiving MOUDs before admission. Additionally, no randomized trials and limited observational studies have evaluated issues related to MOUD use in the ICU. Therefore, ICU clinicians caring for patients admitted who are taking MOUDs must base their decision-making on data extrapolation from pharmacokinetic, pharmacologic, and clinical studies performed in non-ICU settings.

SUMMARY

Despite the challenges in administering MOUDs in critically ill patients, extrapolation of data from other hospital settings suggests that the benefits of continuing MOUD therapy outweigh the risks in patients able to continue therapy. This article provides guidance for critical care clinicians caring for patients admitted to the ICU already receiving methadone, buprenorphine, or extended-release naltrexone. The guidance includes algorithms to aid clinicians in the clinical decision-making process, recognizing the inherent limitations of the existing evidence on which the algorithms are based and the need to account for patient-specific considerations.

Characterizing Opioid Withdrawal Experiences and Consequences Among a Community Sample of People Who Use Opioids

BACKGROUND

Opioid withdrawal symptoms are a highly salient and consequential health condition experienced by people who use opioids (PWUO). This study utilized qualitative interviews to explore opioid withdrawal experiences and consequences among PWUO in Los Angeles County, USA.

METHODS

Semi-structured qualitative interviews were conducted with 22 PWUO (aged 27-63 years) between May 2021 and May 2022. Participants self-reported opioid and injection drug use in the last 30 days. We employed an inductive thematic approach to systematically code and synthesize textual interview data.

RESULTS

Participants experienced withdrawal symptoms frequently, with many going to great lengths to avoid them. Withdrawal pain was described as incapacitating and interfered with PWUO's ability to sustain regular employment and ensure stable housing. Avoiding withdrawal was described as influential in driving decisions to continue using opioids. Mechanisms for managing withdrawal included using other substances to the point of sedation. PWUO who transitioned from heroin to fentanyl use revealed more frequent, painful, and faster onset of withdrawal symptoms. Adverse withdrawal experiences and fear of precipitated withdrawal from buprenorphine were barriers to treatment initiation and continuation.

CONCLUSION

Withdrawal symptoms among PWUO increase health risk. Improved strategies to treat opioid withdrawal are urgently needed. Solutions such as safe supply and intentional opioid withdrawal interventions (educational trainings, withdrawal comfort kits) are needed to improve withdrawal management and reduce opioid-related harm.

Low dose lofexidine for medically directed outpatient opioid tapering in adults with chronic pain: a prospective case series

BACKGROUND

In adults with chronic pain, mild-to-moderate withdrawal symptoms during medically directed opioid tapering in the outpatient setting may not be accompanied by hypertension or tachycardia. This clinical scenario could limit the use of lofexidine at dosages reported in clinical trials of opioid withdrawal precipitated by abrupt opioid discontinuation. Thus, the primary aim of this prospective case series is to describe the use of low dose lofexidine for opioid withdrawal in patients with chronic pain undergoing medically directed opioid tapering in an outpatient setting.

METHODS

Six patients (white 5, Latino 1) admitted to an outpatient interdisciplinary pain rehabilitation program met inclusion and exclusion criteria. Patients self-selected to undergo medically directed opioid tapering, and the medication the patients were prescribed upon admission was used in the taper schedule. Upon initiation of the opioid taper, patients received 0.18 mg of lofexidine every 6 hours.

RESULTS

Five of the six patients were women, and the median morphine milligram equivalents at baseline were 36.9. The median taper duration was 15 days, and the median duration of lofexidine administration was 14 days. Withdrawal scores were mild throughout the taper in four patients, and two patients with fibromyalgia experienced single episodes of moderately severe withdrawal symptoms at the median morphine milligram equivalent midpoint of the taper. No hypotension or sustained bradycardia were observed, and no adverse effects related to lofexidine were reported.

CONCLUSION

The observations from this prospective case series suggest that low-dose lofexidine may be a feasible adjunct medication to attenuate withdrawal symptoms in adults with chronic pain undergoing outpatient opioid tapering.

The Role of Estrogen Signaling and Exercise in Drug Abuse: A Review

BACKGROUND

Discovering how sex differences impact the efficacy of exercise regimens used for treating drug addiction is becoming increasingly important. Estrogen is a hormone believed to explain a large portion of sex differences observed during drug addiction, and why certain exercise regimens are not equally effective between sexes in treatment. Addiction is currently a global hindrance to millions, many of whom are suffering under the influence of their brain's intrinsic reward system coupled with external environmental factors. Substance abuse disorders in the U.S. alone cost billions of dollars annually.

REVIEW SUMMARY

Studies involving the manipulation of estrogen levels in female rodents, primarily via ovariectomy, highlight its impact regarding drug addiction. More specifically, female rodents with higher estrogen levels during the estrus phase increase cocaine consumption, whereas those in the non-estrus phase (low estrogen levels) decrease cocaine consumption. If estrogen is reintroduced, self-administration increases once again. Exercise has been proven to decrease relapse tendency, but its effect on estrogen levels is not fully understood.

CONCLUSIONS

Such findings and results discussed in this review suggest that estrogen influences the susceptibility of females to relapse. Therefore, to improve drug-abuse-related treatment, exercise regimens for females should be generated based on key sex differences with respect to males.

Repeated measures analysis of opioid use disorder treatment on clinical opiate withdrawal scale in a randomized clinical trial: sex differences

PURPOSE

Sex differences may exist in opioid use disorder (OUD) treatment. This study examined the treatment effects of buprenorphine/naloxone (BUP/NX) and methadone (MET) on the Clinical Opiate Withdrawal Scale (COWS) score in individuals with OUD and tested whether the associations differ by sex.

METHOD

We performed a secondary analysis of the data from the National Drug Abuse Treatment Clinical Trials Network (CTN) protocol-0027. A total of 1269 participants (861 males and 408 females) being aged 18 or older with OUD were randomly assigned to receive BUP/NX (n = 740) or MET (n = 529). The paired t test was initially used to compare the COWS scores between pre-dose and post-dose for BUP/NX and MET treatments, separately. The linear mixed model was used to examine the changes in COWS score adjusted for baseline demographic, substance use, and mental health disorders. The interaction of sex and treatment was detected and stratified analysis by sex was conducted.

RESULTS

The paired t test showed that both BUP/NX and MET treatments significantly reduced the COWS scores (p values <0.0001). BUP/NX revealed higher COWS scores than MET (p = 0.0008) and females demonstrated significantly higher COWS scores than males (p = 0.0169). Stratified by sex, BUP/NX compared with MET revealed higher COWS scores only in males (p = 0.0043), whereas baseline amphetamines use disorder and major depressive disorder were significantly associated with COWS scores in females (p = 0.0158 and 0.0422, respectively).

CONCLUSIONS

Both BUP/NX and MET are effective in decreasing opioid withdrawal symptoms via COWS scores, however, treatment plans for OUD by clinical providers should consider sex differences.

AKAP150 from nucleus accumbens dopamine D1 and D2 receptor-expressing medium spiny neurons regulates morphine withdrawal

Dopamine D1 receptor-expressing medium spiny neurons (D1R-MSNs) and dopamine D2 receptor-expressing MSNs (D2R-MSNs) in nucleus accumbens (NAc) have been demonstrated to show different effects on reward and memory of abstinence. A-kinase anchoring protein 150 (AKAP150) expression in NAc is significantly upregulated and contributes to the morphine withdrawal behavior. However, the underlying mechanism of AKAP150 under opioid withdrawal remains unclear. In this study, AKAP150 expression in NAc is upregulated in naloxone-precipitated morphine withdrawal model, and knockdown of AKAP150 alleviates morphine withdrawal somatic signs and improves the performance of conditioned place aversion (CPA) test. AKAP150 in NAc D1R-MSNs is related to modulation of the performance of morphine withdrawal CPA test, while AKAP150 in NAc D2R-MSNs is relevant to the severity of somatic responses. Our results suggest that AKAP150 from D1R-MSNs or D2R-MSNs in NAc contributes to the developmental process of morphine withdrawal but plays different roles in aspects of behavior or psychology.

Erythrocytic metabolism of ATLX-0199: An agent that increases minute ventilation

Both L- and D-isomers of S-nitrosocysteine (CSNO) can bind to the intracellular domain of voltage-gated potassium channels in vitro. CSNO binding inhibits these channels in the carotid body, leading to increased minute ventilation in vivo. However, only the l-isomer is active in vivo because it requires the l-amino acid transporter (LAT) for transmembrane transport. In rodents and dogs, the esterified D-CSNO precursor-d-cystine dimethyl ester (ATLX-0199)-overcomes opioid- and benzodiazepine-induced respiratory depression while maintaining analgesia. Although ATLX-0199 can enter cells independently of LAT because it is an ester, its stability in plasma is limited by the presence of esterases. Here, we hypothesized that the drug could be sequestered in erythrocytes to avoid de-esterification in circulation. We developed a liquid chromatography-mass spectrometry method for detecting ATLX-0199 and characterized a new metabolite, S-nitroso-d-cysteine monomethyl ester (DNOCE), which is also a D-CSNO precursor. We found that both ATLX-0199 and DNOCE readily enter erythrocytes and neurons and remain stable over 20 min; thus ATLX-0199 can enter cells where the ester is stable, but the thiol is reduced. Depending on hemoglobin conformation, the reduced ester can be S-nitrosylated and enter carotid body neurons, where it then increases minute ventilation. These data may help explain the paradox that ATLX-0199, a dimethyl ester, can avoid de-esterification in plasma and exert its effects at the level of the carotid body.

Prevalence and correlates of DSM-5 opioid withdrawal syndrome in U.S. adults with non-medical use of prescription opioids: results from a national sample

Background: In the U.S. non-medical use of prescription opioids (NMOU) is prevalent and often accompanied by opioid withdrawal syndrome (OWS). OWS has not been studied using nationally representative data.Objectives: We examined the prevalence and clinical correlates of OWS among U.S. adults with NMOU.Methods: We used data from 36,309 U.S. adult participants in the 2012-2013 National Epidemiologic Survey on Alcohol and Related Conditions-III, 1,527 of whom reported past 12-month NMOU. Adjusted linear and logistic regression models examined associations between OWS and its clinical correlates, including psychiatric disorders, opioid use disorder (OUD; excluding the withdrawal criterion), medical conditions, and healthcare utilization among people with regular (i.e. ≥3 days/week) NMOU (n = 534).Results: Over half (50.4%) of the sample was male. Approximately 9% of people with NMOU met criteria for DSM-5 OWS, with greater prevalence of OWS (∼20%) among people with regular NMOU. Individuals with bipolar disorder, dysthymia, panic disorder, and borderline personality disorder had greater odds of OWS (aOR range = 2.71-4.63). People with OWS had lower mental health-related quality of life (β=-8.32, p < .001). Individuals with OUD also had greater odds of OWS (aOR range = 26.02-27.77), an association that increased with more severe OUD. People using substance use-related healthcare services also had greater odds of OWS (aOR range = 6.93-7.69).Conclusion: OWS was prevalent among people with OUD and some psychiatric disorders. These findings support screening for OWS in people with NMOU and suggest that providing medication- assisted treatments and behavioral interventions could help to reduce the burden of withdrawal in this patient population.

Gender Differences in Civil Commitment Hearing Experience for Persons Who Use Opioids

OBJECTIVES

Civil commitment has increasingly served as a court-based legal intervention for severe opioid use, but little research has examined the civil commitment (CC) hearing process from the perspective of the person who is committed. Despite documented gender differences in opioid use and experiences within the legal system, past research has also not investigated gender differences in perceptions of the CC process for persons who use opioids.

METHODS

Participants were 121 persons (43% female) with opioid use who were interviewed upon arrival at the CC facility about their experience of the CC hearing process in Massachusetts.

RESULTS

Two thirds of participants were taken to the commitment hearing by police, and 59.5% shared a cell with others while waiting. Overall, the commitment intake process at the courthouse took over 5 hours. Participants spent, on average, less than 15 minutes with their lawyer before the hearing, and a majority of CC hearings lasted less than 15 minutes. Once transferred to a CC facility, opioid withdrawal management began within 4 hours. Compared with women, men reported longer wait times between the hearing and transfer, as well as longer wait times for withdrawal management at the facility ( P < 0.05). Women perceived worse interactions with the judge and greater dissatisfaction with the commitment process compared with men ( P < 0.05).

CONCLUSIONS

There were few gender differences in the experience of CC. However, overall, participants reported a lengthy court process and low levels of perceived procedural justice.

Case report: The lesson from opioid withdrawal symptoms mimicking paraganglioma recurrence during opioid deprescribing in cancer pain

Pain is one of the predominant and troublesome symptoms that burden cancer patients during their whole disease trajectory: adequate pain management is a fundamental component of cancer care. Opioid are the cornerstone of cancer pain relief therapy and their skillful management must be owned by physicians approaching cancer pain patients. In light of the increased survival of cancer patients due to advances in therapy, deprescription should be considered as a part of the opioid prescribing regime, from therapy initiation, dose titration, and changing or adding drugs, to switching or ceasing. In clinical practice, opioid tapering after pain remission could be challenging due to withdrawal symptoms' onset. Animal models and observations in patients with opioid addiction suggested that somatic and motivational symptoms accompanying opioid withdrawal are secondary to the activation of stress-related process (mainly cortisol and catecholamines mediated). In this narrative review, we highlight how the lack of validated guidelines and tools for cancer patients can lead to a lower diagnostic awareness of opioid-related disorders, increasing the risk of developing withdrawal symptoms. We also described an experience-based approach to opioid withdrawal, starting from a case-report of a symptomatic patient with a history of metastatic pheochromocytoma-paraganglioma.

Developing non-opioid therapeutics to alleviate pain among persons with opioid use disorder: a review of the human evidence

The opioid crisis remains a major public health concern, causing significant morbidity and mortality worldwide. Pain is frequently observed among individuals with opioid use disorder (OUD), and the current opioid agonist therapies (OAT) have limited efficacy in addressing the pain needs of this population. We reviewed the most promising non-opioid analgesic therapies for opioid-dependent individuals synthesising data from randomised controlled trials in the Medline database from December 2022 to March 2023. Ketamine, gabapentin, serotoninergic antidepressants, and GABAergic drugs were found to be the most extensively studied non-opioid analgesics with positive results. Additionally, we explored the potential of cannabinoids, glial activation inhibitors, psychedelics, cholecystokinin antagonists, alpha-2 adrenergic agonists, and cholinergic drugs. Methodological improvements are required to advance the development of novel analgesic strategies and establish their safety profile for opioid-dependent populations. We highlight the need for greater integration of experimental pain methods and abuse liability assessments, more granular assessments of prior opioid exposure, greater uniformity of pain types within study samples, and a particular focus on individuals with OUD receiving OAT. Finally, future research should investigate pharmacokinetic interactions between OAT and various non-opioid analgesics and perform reverse translation basic experiments, particularly with methadone and buprenorphine, which remain the standard OUD treatment.

Molecular mechanisms of morphine tolerance and dependence; novel insights and future perspectives

Drug addiction is a devastating condition that poses a serious burden on the society. The use of some drugs like morphine for their tremendous analgesic properties is also accompanied with developing tolerance, dependence and the withdrawal symptoms. These symptoms are frequently severe enough to reinforce the person in recovery to start over the use of drug again and hinder the clinical use of drugs like morphine for chronic pain. Research into opioid receptors and related molecular pathways has seen resurgence in the wake of the growing opioid epidemic. The current study provides a comprehensive scientific exploration of the molecular mechanisms and underlying signalling in morphine tolerance and dependence. It also critically evaluates current therapeutic approaches, shedding light on their efficacy and limitations, and future prospects. The graphical abstract depicts an overview of the pathways involved in the emergence of morphine-related tolerance and dependence including NMDA, Nitric oxide, and PPAR, as well as behavioural sensitization along with present and future innovative treatment strategies including stem cell therapy that have been discussed in the current manuscript.

Acupuncture for protracted opioid abstinence syndrome: study protocol for a systematic review and meta-analysis

INTRODUCTION

Protracted opioid abstinence syndrome (POAS) refers to a series of physical discomforts and neuropsychiatric symptoms after discontinuation of opioid-type substances for a certain amount of time and is one of the main causes of relapse. Studies have shown that acupuncture is effective in the treatment of POAS. We plan to conduct this systematic review and meta-analysis to assess the efficacy and safety of acupuncture for POAS.

METHODS AND ANALYSIS

A comprehensive search of studies will be carried out in the following databases from inception to 31 January 2023: Web of Science, Embase, PubMed, Chinese Biology Medicine, China National Knowledge Infrastructure, Wan Fang Database and Chinese Scientific Journal Database (VIP). WHO International Clinical Trials Registry Platform, ClinicalTrials.gov and Chinese Clinical Trial Registry will also be searched for ongoing relevant trials, and 'grey literatures' will be identified from GreyNet International, OpenGrey and Google Scholar. Randomised controlled trials regarding acupuncture therapy for treatment of POAS will be included. The primary outcome is the severity of protracted withdrawal symptoms. Two reviewers will screen studies using the inclusion criteria, extract data and assess the risk of bias, respectively. The quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation. Data synthesis will be performed using RevMan V.5.4.1.

ETHICS AND DISSEMINATION

This study will not invade patients' personal privacy, and so ethical review is not required. The results will be disseminated in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022382978.

Substance Use and the Nervous System

OBJECTIVE

This article informs and updates the practicing neurologist on the current landscape of known neurologic injuries linked to the use of illicit drugs, focusing on emerging agents.

LATEST DEVELOPMENTS

Synthetic opioids such as fentanyl and similar derivatives have exploded in prevalence, becoming the leading cause of overdose fatalities. The higher potency of synthetic opioids compared with semisynthetic and nonsynthetic opiates poses an increased risk for unintentional overdose when found as an adulterant in other illicit drug supplies such as heroin. Conversely, misinformation about the risk of symptomatic exposure to fentanyl through casual contact with the skin and ambient air has led to misdirected fear and stigma that threatens to impede valid harm-reduction measures for fentanyl users at risk of actual overdose. Finally, during the COVID-19 pandemic, overdose rates and deaths continued to climb, especially among those who use opioids and methamphetamine.

ESSENTIAL POINTS

A variety of potential neurologic effects and injuries can occur with illicit drug use owing to the diverse properties and mechanisms of action of the various classes. Many high-risk agents are not detected on standard drug screens, including so-called designer drugs, and the practicing neurologist is best served by recognizing the clinical features of the traditional toxidrome and other potential idiosyncratic effects of various illicit agents.

A randomized controlled trial on the seeds of Sophora alopecuroides var. alopecuroides for the treatment of acute heroin withdrawal syndrome

BACKGROUND

and purpose: The seeds of Sophora alopecuroides var. alopecuroides have attenuated the acute opium withdrawal syndrome in humans. Therefore, the efficacy and safety of a standardized extract of the plant for the treatment of acute heroin withdrawal syndrome was evaluated in abstinent heroin addicts.

MATERIALS AND METHODS

The patients were randomized to take three 400 mg extract capsules (N = 50) or placebo (N = 50) once per day orally for eight days. The severity of withdrawal syndrome was assessed by the clinical opiate withdrawal scale (COWS) as the primary outcome measure at the baseline and on the days 3 and 8. The hepatic and renal functions and complete blood count were the secondary outcome measures tested at the baseline and end of the study.

RESULTS

The COWS score decreased in both groups after eight days, but the decrease was significantly higher in the experimental group (p < 0.001); the effect size of the decrease was 2.64. The groups had significant differences in the COWS scores on the days 3 and 8 (p < 0.001 for both). The extract had no significant effect on the other parameters. No side effect was noted.

CONCLUSION

The extract seems to alleviate acute heroin withdrawal syndrome safely.

Feasibility study of a Behavioural Intervention for Opioid Reduction (BIOR) for patients with chronic non-cancer pain in primary care: a protocol

INTRODUCTION

Around 30%-50% of adults suffer moderate to severe chronic pain not caused by cancer. Significant numbers are treated with opioids which over time may cease to be effective and produce side effects (eg, nausea, drowsiness and constipation). Stopping taking opioids abruptly can cause unpleasant withdrawal effects. Tapering in small steps is recommended, though some patients might struggle and need support, particularly if they have limited access to pain management alternatives. Awareness of the potential risks as well as benefits of tapering should be explored with patients.

METHODS AND ANALYSIS

A randomised controlled pilot feasibility study to investigate the effectiveness and feasibility of reducing high doses of opioids through a tapering protocol, education and support in primary care. Working with NHS Knowsley Place, we will identify patients taking 50 mg or above morphine equivalent dose of opioids per day to be randomly allocated to either the tapering group or tapering with support group. At an initial joint appointment with a pain consultant and General Practitioner (GP) GP tapering will be discussed and negotiated. Both groups will have their opioid reduced by 10% per week. The taper with support group will have access to additional support, including motivational counselling, realistic goal setting and a toolkit of resources to promote self-management. Some patients will successfully reduce their dose each week. For others, this may be more difficult, and the tapering reduction will be adjusted to 10% per fortnight. We assess opioid use, pain and quality of life in both groups at the start and end of the study to determine which intervention works best to support people with chronic pain who wish to stop taking opioids.

ETHICS AND DISSEMINATION

The Behavioural Intervention for Opioid Reduction feasibility study has been granted full approval by Liverpool Central Research Ethics Committee on 7 April 2022 (22/NW/0047). The current protocol version is V.1.1, date 6 July 2022. Results will be published in peer-reviewed journals and disseminated to patient stakeholders in a lay summary report available on the project website and in participating GP surgeries.

TRIAL REGISTRATION NUMBER

ISRCTN 30201337.

The gut microbiome contributes to somatic morphine withdrawal behavior and implicates a TLR2 mediated mechanism

The ongoing opioid epidemic has left millions of people suffering from opioid use disorder due to the over-prescription of highly addictive substances. Chronic opioid exposure leads to dependence, where the absence of the drug results in negative symptoms of withdrawal, often driving patients to continue drug use; however, few therapeutic strategies are currently available to combat the cycle of addiction and the severity of morphine withdrawal. This study investigates the microbiome as a potential therapeutic target for morphine withdrawal, as gut dysbiosis caused by morphine use has been proven to contribute to other aspects of opioid use disorders, such as tolerance. Results show that although the microbiome during morphine withdrawal trends toward recovery from morphine-induced dysbiosis, there continues to be a disruption in the alpha and beta diversity as well as the abundance of gram-positive bacteria that may still contribute to the severity of morphine withdrawal symptoms. Germ-free mice lacking the microbiome did not develop somatic withdrawal symptoms, indicating that the microbiome is necessary for the development of somatic withdrawal behavior. Notably, only TLR2 but not TLR4 whole-body knockout models display less withdrawal severity, implicating that the microbiome, through a gram-positive, TLR2 mediated mechanism, drives opioid-induced somatic withdrawal behavior.

Identifying Clinically Relevant Drug-Drug Interactions With Methadone and Buprenorphine: A Translational Approach to Signal Detection

Methadone and buprenorphine have pharmacologic properties that are concerning for a high risk of drug-drug interactions (DDIs). We performed high-throughput screening for clinically relevant DDIs with methadone or buprenorphine by combining pharmacoepidemiologic and pharmacokinetic approaches. We conducted pharmacoepidemiologic screening via a series of self-controlled case series studies (SCCS) in Optum claims data from 2000 to 2019. We included persons 18 years or older who experienced an outcome of interest during target drug treatment. Exposures were all overlapping medications (i.e., the candidate precipitants) during target drug treatment. Outcomes were opioid overdose, non-overdose adverse effects, and cardiac arrest. We used conditional Poisson regression to calculate rate ratios, accounting for multiple comparisons with semi-Bayes shrinkage. We explored the impact of key study design choices in analyses that varied the exposure definitions of the target drugs and the candidate precipitant drugs. Pharmacokinetic screening was conducted by incorporating published data on CYP enzyme metabolism into an equation-based static model. In SCCS analysis, 1,432 events were included from 248,069 new users of methadone or buprenorphine. In the primary analysis, statistically significant DDIs included gabapentinoids with either methadone or buprenorphine; baclofen with methadone; and benzodiazepines with methadone. In sensitivity analysis, additional statistically significant DDIs included methocarbamol, quetiapine, or simvastatin with methadone. Pharmacokinetic screening identified two moderate-to-strong potential DDIs (clonidine and fluconazole with buprenorphine). The combination of clonidine and buprenorphine was also associated with a significantly increased risk of opioid overdose in pharmacoepidemiologic screening. These DDI signals may be the most important targets for future confirmation studies.

Hypermethylation in the promoter region of the ADRA1A gene is associated with opioid use disorder in Han Chinese

Opioid use disorder is a chronic brain disease influenced by genetic and epigenetic factors, accounting for approximately 50% of the liability. Adrenergic signaling is involved in opioid use disorder. To demonstrate the associations between methylation alterations in the alpha-1-adrenergic receptor (ADRA1A) gene and opioid use disorder, in the present study, we first examined and compared the methylation levels of 97 CpG sites in the promoter region of the ADRA1A gene in the peripheral blood in 120 patients with heroin use disorder and 111 healthy controls. Correlations between methylation levels and duration of heroin/methadone use were then analyzed. Finally, the predicted binding transcription factors (TFs) and their target sequences in the promoter region of the ADRA1A gene, which include the selected CpG sites, were screened in the JASPAR database. Our results demonstrated that hypermethylation in the promoter region of the ADRA1A gene in the blood was associated with opioid use disorder. Correlations between methylation levels of several CpG sites and duration of heroin/methadone use were observed. TFs TFAP2A and RUNX1 were predicted to bind to the target sequences, which include the CpG sites selected in the current study, in the promoter region of the ADRA1A gene. Our findings further extend the associations between methylation alterations in the ADRA1A gene and opioid use disorder potentially through mechanisms of gene expression regulations in the ADRA1A gene.

Historical Pathways for Opioid Addiction, Withdrawal with Traditional and Alternative Treatment Options with Ketamine, Cannabinoids, and Noribogaine: A Narrative Review

Even as prescription opioid dispensing rates have begun to decrease, the use of illicit opioids such as heroin and fentanyl has increased. Thus, the end of the opioid epidemic is not in sight, and treating patients that are addicted to opioids remains of utmost importance. Currently, the primary pharmacotherapies used to treat opioid addiction over the long term are the opioid antagonist naltrexone, the partial-agonist buprenorphine, and the full agonist methadone. Naloxone is an antagonist used to rapidly reverse opioid overdose. While these treatments are well-established and used regularly, the gravity of the opioid epidemic necessitates that all possible avenues of treatment be explored. Therefore, in this narrative review, we analyze current literature regarding use of the alternative medications ketamine, noribogaine, and cannabinoids in treating patients suffering from opioid use disorder. Beyond its use as an anesthetic, ketamine has been shown to have many applications in several medical specialties. Of particular interest to the subject at hand, ketamine is promising in treating individuals addicted to opioids, alcohol, and cocaine. Therapeutically administered cannabinoids have been proposed for the treatment of multiple illnesses. These include, but are not limited to epilepsy, Parkinson's disease, multiple sclerosis, chronic pain conditions, anxiety disorders, and addiction. The cannabinoid dronabinol has been seen to have varying effects. High doses appear to reduce withdrawal symptoms but this comes at the expense of increased adverse side effects such as sedation and tachycardia. Noribogaine is a weak MOR antagonist and relatively potent KOR agonist, which may explain the clinical anti-addictive effects. More research should be done to assess the viability of these medications for the treatment of OUD and withdrawal.

Prevention, diagnosis, and treatment of opioid use disorder under the supervision of opioid stewardship programs: it's time to act now

The third opium war may have already started, not only due to illicit opioid trafficking from the Golden Crescent and Golden Triangle on the international front but also through indiscriminate opioid prescription and opioid diversion at home. Opioid use disorder (OUD), among unintentional injuries, has become one of the top 4 causes of death in the United States (U.S.). An OUD is defined as a problematic pattern of opioid use resulting in clinically significant impairment or distress, consisting of 2 or more of 11 problems within 1 year, as described by the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition. Observation of aberrant behaviors of OUD is also helpful for overworked clinicians. For the prevention of OUD, the Opioid Risk Tool and the Current Opioid Misuse Measure are appropriate screening tests before and during opioid administration, respectively. Treatment of OUD consists of 3 opioid-based U.S. Food and Drug Administration-approved medications, including methadone, buprenorphine, and naltrexone, and non-opioid-based symptomatic medications for reducing opioid withdrawal syndromes, such as α2 agonists, β-blockers, antidiarrheals, antiemetics, non-steroidal anti-inflammatory drugs, and benzodiazepines. There are at least 6 recommendable guidelines and essential terms related to OUD. Opioid stewardship programs are now critical to promoting appropriate use of opioid medications, improving patient outcomes, and reducing misuse of opioids, influenced by the successful implementation of antimicrobial stewardship programs. Despite the lack of previous motivation, now is the critical time for trying to reduce the risk of OUD.

"It's Like Your Whole Body Hates You": Experiences of Withdrawal, Distress, and Barriers to Relief Among Adults Receiving Methadone for Opioid Use Disorder

ABSTRACT

A qualitative descriptive study was conducted concurrent with a larger study investigating the effects of hyperbaric oxygen treatment on withdrawal symptoms for adults receiving daily methadone for opioid use disorder. The aims of this study were to (a) evaluate the perceptions of withdrawal symptoms and sleep characteristics of study participants and (b) explore the experiences of participation in the parent trial of hyperbaric oxygen treatment.Adults with opioid use disorder can experience distressing symptoms related to withdrawal as well as co-occurring symptoms; sleep impairment is frequently reported. Few studies have examined how adults who receive medication for opioid use disorder experience sleep. A preliminary study of adults receiving daily methadone found that withdrawal symptoms were improved after hyperbaric oxygen treatment. This study explores the narrative of opioid users who report their overall experiences with withdrawal and sleep as well as their experiences of hyperbaric therapy.A convenience sample of six participants was recruited, who represented a small subgroup of participants who completed the larger hyperbaric treatment study. Data were collected via semistructured interviews. Data were analyzed using the qualitative content analysis guidelines proposed by Schreier (2012). All participants described poor overall sleep hygiene and disturbed sleep. More than half of the respondents reported improved or eliminated withdrawal symptoms, and all reported improvement in sleep quality after participation in the sleep study.This companion study confirms that subjective sleep disturbance may be prevalent for adults with opioid use disorder. Participants felt the experience of hyperbaric oxygen treatment produced a positive effect on sleep.

Opioid tolerance and opioid-induced hyperalgesia: Is TrkB modulation a potential pharmacological solution?

Opioids are widely prescribed for moderate to severe pain in patients with acute illness, cancer pain, and chronic noncancer pain. However, long-term opioid use can cause opioid tolerance and opioid-induced hyperalgesia (OIH), contributing to the opioid misuse and addiction crisis. Strategies to mitigate opioid tolerance and OIH are needed to reduce opioid use and its sequelae. Currently, there are few effective pharmacological strategies that reduce opioid tolerance and OIH. The intrinsic tyrosine kinase receptor B (TrkB) ligand, brain-derived neurotrophic factor (BDNF), has been shown to modulate pain. The BDNF-TrkB signaling plays a role in initiating and sustaining elevated pain sensitivity; however, increasing evidence has shown that BDNF and 7,8-dihydroxyflavone (7,8-DHF), a potent blood-brain barrier-permeable ligand to TrkB, exert neuroprotective, anti-inflammatory, and antioxidant effects that may protect against opioid tolerance and OIH. As such, TrkB signaling may be an important therapeutic avenue in opioid tolerance and OIH. Here, we review 1) the mechanisms of pain, opioid analgesia, opioid tolerance, and OIH; 2) the role of BDNF-TrkB in pain modulation; and 3) the neuroprotective effects of 7,8-DHF and their implications for opioid tolerance and OIH.

Clinical Management of Opioid Withdrawal

Appropriate clinical management of opioid withdrawal is a crucial bridge to long-term treatment for opioid use disorder (OUD), because it is a high-risk time for potential opioid overdose and relapse. We provide a narrative review of evidence-based opioid withdrawal management strategies applicable to a variety of treatment settings and geographies. The goals of opioid withdrawal management include relieving suffering associated with withdrawal, providing appropriate diagnosis and screening, engaging patients in initiation of OUD treatment, and using harm reduction strategies, all guided by a patient-centered approach to care. In addition, we discuss complex cases, relapse prevention strategies, and new developments in opioid withdrawal management.

French-Canadian Translation and Cultural Adaptation of the Clinical Opiate Withdrawal Scale: The COWS-FC

OBJECTIVE

The main objective of the present study was to develop a French-Canadian translation and adaptation of the COWS (i.e., the COWS-FC) for the assessment of opioid withdrawal symptoms in clinical and research settings.

METHODS

The French-Canadian translation and cultural adaptation of the COWS was performed following guidelines for the translation and cross-cultural adaptation of self-report measures. The steps consisted of (1) initial translation from English to French, (2) synthesis of the translation, (3) back-translation from French to English, (4) expert committee meeting, (5) test of the prefinal version among healthcare professionals and (6) review of final version by the expert committee. The expert committee considered four major areas where the French-Canadian version should achieve equivalence with the original English-version of the COWS. These areas were (1) semantic equivalence; (2) idiomatic equivalence; (3) experiential equivalence and (4) conceptual equivalence.

RESULTS

Rigorous steps based on the guidelines for the translation and cultural adaptation of assessment tools were followed, which led to a semantically equivalent version of the COWS. After a pretest among healthcare professionals, members from the expert committee agreed upon slight modifications to the French-Canadian version of the COWS to yield a final COWS-FC version.

CONCLUSIONS

A French-Canadian translation and adaptation of the COWS (i.e., the COWS-FC) was developed. The COWS-FC could be used for the assessment of opioid withdrawal symptoms in clinical and research settings.

Oxycodone decreases anxiety-like behavior in the elevated plus-maze test in male and female rats

The prescription opioid oxycodone is widely used for the treatment of pain in humans. Oxycodone misuse is more common among people with an anxiety disorder than those without one. Therefore, oxycodone might be misused for its anxiolytic properties. We investigated if oxycodone affects anxiety-like behavior in adult male and female rats. The rats were treated with oxycodone (0.178, 0.32, 0.56, or 1 mg/kg), and anxiety-like behavior was investigated in the elevated plus-maze test. Immediately after the elevated plus-maze test, a small open field test was conducted to determine the effects of oxycodone on locomotor activity. In the elevated plus-maze test, oxycodone increased the percentage of time spent on the open arms, the percentage of open arm entries, time on the open arms, open arm entries, and the distance traveled. The males treated with vehicle had a lower percentage of open arm entries than the females treated with vehicle, and oxycodone treatment led to a greater increase in the percentage of open arm entries in the males than females. Furthermore, the females spent more time on the open arms, made more open arm entries, spent less time in the closed arms, and traveled a greater distance than the males. In the small open field test, treatment with oxycodone did not affect locomotor activity or rearing. Sex differences were observed; the females traveled a greater distance and displayed more rearing than the males. In conclusion, oxycodone decreases anxiety-like behavior in rats, and oxycodone has a greater anxiolytic-like effect in males than females.

Delivering transcutaneous auricular neurostimulation (tAN) to improve symptoms associated with opioid withdrawal: results from a prospective clinical trial

Background

As pharmacological treatments are the primary option for opioid use disorder, neuromodulation has recently demonstrated efficacy in managing opioid withdrawal syndrome (OWS). This study investigated the safety and effectiveness of transcutaneous auricular neurostimulation (tAN) for managing OWS.

Methods

This prospective inpatient trial included a 30-minute randomized, sham-controlled, double-blind period followed by a 5-day open-label period. Adults with physical dependence on opioids were randomized to receive active or sham tAN following abrupt opioid discontinuation. The Clinical Opiate Withdrawal Scale (COWS) was used to determine withdrawal level, and participants were required to have a baseline COWS score ≥ 13 before enrollment. The double-blind period of the study occurred during the first 30-minutes to assess the acute effects of tAN therapy compared to a sham control. Group 1 received active tAN during both the 30-minute double-blind period and the 5-day open-label period. Group 2 received passive sham tAN (no stimulation) during the double-blind period, followed by active tAN during the 5-day open-label period. The primary outcome was change in COWS from baseline to 60-minutes of active tAN (pooled across groups, accounting for 30-minute delay). Secondary outcomes included difference in change in COWS scores between groups after 30-minutes of active or sham tAN, change in COWS scores after 120-minutes of active tAN, and change in COWS scores on Days 2–5. Non-opioid comfort medications were administered during the trial.

Results

Across all thirty-one participants, the mean (SD) COWS scores relative to baseline were reduced by 7.0 (4.7) points after 60-minutes of active tAN across both groups (p < 0.0001; Cohen’s d = 2.0), demonstrating a significant and clinically meaningful reduction of 45.9%. After 30-minutes of active tAN (Group 1) or sham tAN (Group 2), the active tAN group demonstrated a significantly greater COWS score reduction than the sham tAN group (41.7% vs. 24.1%; p = 0.036). Participants across both groups achieved an average COWS reduction up to 74.7% on Days 2–5.

Conclusion

Results demonstrate tAN is a safe and effective non-opioid approach for reducing symptoms of OWS. This study supported an FDA clearance.

Clinical trial registration

clinicaltrials.gov/ct2/show/NCT04075214, Identifier: NCT04075214, Release Date: August 28, 2019.

Management of opioid withdrawal and initiation of medications for opioid use disorder in the hospital setting

Opioid use disorder (OUD) has become increasingly prevalent among hospitalized patients in the United States and globally. As its prevalence increases, this provides a valuable opportunity for clinicians in the hospital setting to engage and initiate management and treatment of OUD. This article aims to provide hospitalists and other clinicians working in the hospital with a narrative review of the management of opioid withdrawal and the initiation of medications for opioid use disorder (MOUD) in the hospital and provide an update on a novel low dose approach to buprenorphine induction (also commonly referred to as the "microinduction" method). Management can initially include treating withdrawal symptoms with opioids as well as with a combination of non-opioid medications such as alpha 2 agonists, benzodiazepines, and/or antiemetics as needed. Besides simply managing withdrawal symptoms, clinicians can further improve the care of patients with OUD through initiating maintenance treatment with MOUD, ideally with opioids used in the initial management of withdrawal. Opioid detoxification is an inferior method of primary treatment and is associated with relapse and poor outcomes. In contrast, treatment with MOUD using methadone or buprenorphine is associated with superior treatment outcomes and reduced relapse compared to detoxification alone. Treatment with MOUD using methadone or buprenorphine can be successfully used in the hospital setting. A novel low dose approach to buprenorphine induction may be useful in minimizing precipitated withdrawals in patients who have recently used or received opioids, which makes this an attractive option in the hospital where patients are frequently on opioids for acutely painful conditions. The hospital setting also provides a valuable opportunity for clinicians to address harm reduction in patients with OUD. Finally, clinicians can improve the long-term outcomes of patients with OUD by ensuring a smooth discharge with adequate and timely follow-up.

Opioid Antagonist Nanodrugs Successfully Attenuate the Severity of Ischemic Stroke

The United States is in the midst of an opioid epidemic that is linked to a number of serious health issues, including an increase in cerebrovascular events, namely, stroke. Chronic prescription opioid use exacerbates the risk and severity of ischemic stroke, contributing to stroke as the fifth overall cause of death in the United States and costing the US health care system over $30 billion annually. Pathologically, opioids challenge the integrity of the blood–brain barrier (BBB), resulting in a dysregulation of tight junction (TJ) proteins that are crucial in maintaining barrier homeostasis. Despite this, treatment options for ischemic stroke are limited, and there are no pharmacological options to attenuate TJ damage, including in incidents that are linked to opioid use. Herein, we have generated carrier-free, pure “nanodrugs” or nanoparticles of naloxone and naltrexone with enhanced therapeutic properties compared to the original (parent) drugs. The generated nanoformulations of both opioid antagonists exhibited successful attenuation of morphine- or oxycodone-induced alterations of TJ protein expression and reduced oxidative stress to a greater extent than the parent drugs (non-nano). As a proof of concept, we then proceeded to evaluate the therapeutic effectiveness of the generated nanodrugs in an ischemic stroke model of mice exposed to morphine or oxycodone. Our results demonstrate that the opioid antagonist nanoformulations reduced stroke severity in mice. Overall, this research implements advances in nanotechnology-based repurposing of FDA-approved therapeutics, and the obtained results also suggest underlying pharmacological mechanisms of opioid antagonists, further supporting these opioid antagonists and their respective nanoformulations as potential therapeutic agents for ischemic stroke.

Adrenergic receptors control frequency-dependent switching of the exocytosis mode between "full-collapse" and "kiss-and-run" in murine motor nerve terminal

AIMS

Neurotransmitter release from the synaptic vesicles can occur through two modes of exocytosis: "full-collapse" or "kiss-and-run". Here we investigated how increasing the nerve activity and pharmacological stimulation of adrenoceptors can influence the mode of exocytosis in the motor nerve terminal.

METHODS

Recording of endplate potentials with intracellular microelectrodes was used to estimate acetylcholine release. A fluorescent dye FM1-43 and its quenching with sulforhodamine 101 were utilized to visualize synaptic vesicle recycling.

KEY FINDINGS

An increase in the frequency of stimulation led to a decrease in the rate of FM1-43 unloading despite the higher number of quanta released. High frequency activity promoted neurotransmitter release via the kiss-and-run mechanism. This was confirmed by experiments utilizing (I) FM1-43 dye quencher, that is able to pass into the synaptic vesicle via fusion pore, and (II) loading of FM1-43 by compensatory endocytosis. Noradrenaline and specific α2-adrenoreceptors agonist, dexmedetomidine, controlled the mode of synaptic vesicle recycling at high frequency activity. Their applications favored neurotransmitter release via full-collapse exocytosis rather than the kiss-and-run pathway.

SIGNIFICANCE

At the diaphragm neuromuscular junctions, neuronal commands are translated into contractions necessary for respiration. During stress, an increase in discharge rate of the phrenic nerve shifts the exocytosis from the full-collapse to the kiss-and-run mode. The stress-related molecule, noradrenaline, restricts neurotransmitter release in response to a high frequency activity, and prevents the shift in the mode of exocytosis through α2-adrenoceptor activation. This may be a component of the mechanism that limits overstimulation of the respiratory system during stress.

Hyperbaric Oxygen Therapy for Pain, Opioid Withdrawal, and Related Symptoms: A Pilot Randomized Controlled Trial

BACKGROUND

Pain, drug cravings, and opioid withdrawal symptoms can interfere with substance use disorder or opioid tapering treatment goals.

AIM

This pilot study investigated the feasibility of a protocol designed to test opioid withdrawal symptom relief relative to a sham condition after two consecutive days of hyperbaric oxygen therapy (HBOT) for adults prescribed daily methadone for opioid use disorder.

METHOD

Using a double-blind protocol, eight adults were randomized to receive either a full 90-minute HBOT dose in a pressurized chamber with 100% oxygen at 2.0 atmospheres absolute (ATA) or a sham condition receiving 21% oxygen (equivalent to room air within the chamber) at a minimal pressure of ≤1.3 ATA. Measures included study retention, treatment satisfaction, and pre- and post-intervention effects for opioid withdrawal symptoms, drug cravings, pain intensity and interference, sleep quality, and mood.

RESULTS

Study retention and treatment satisfaction was high. All measurements improved more, on average, for participants receiving full-dose HBOT treatment than among participants receiving sham treatments except for clinically observed withdrawal symptoms. The largest positive effects were observed in measurements of pain intensity and drug craving.

CONCLUSIONS

These pilot results provide evidence to support a fully powered study of HBOT as a potential treatment adjunct for adults receiving methadone for opioid use disorder. Trends towards symptom improvements were detected from pre- to post-HBOT in the full treatment arm versus sham condition. More research into novel non-pharmacologic options to relieve distressing symptoms related to pain and opioid use disorder is essential to improve clinical outcomes.

Innovating for real-world care: A systematic review of interventions to improve post-detoxification outcomes for opioid use disorder

BACKGROUND

Inpatient detoxification is a common health care entry point for people with Opioid Use Disorder (OUD). However, many patients return to opioid use after discharge and also do not access OUD treatment. This systematic review reports on the features and findings of research on interventions developed specifically to improve substance use outcomes and treatment linkage after inpatient detoxification for OUD.

METHODS

Of 6419 articles, 64 met inclusion criteria for the current review. Articles were coded on key domains including sample characteristics, study methods and outcome measures, bias indicators, intervention type, and findings.

RESULTS

Many studies did not report sample characteristics, including demographics and co-occurring psychiatric and substance use disorders, which may impact postdetoxification OUD treatment outcomes and the generalizability of interventions. Slightly more than half of studies examined interventions that were primarily medical in nature, though only a third focused on initiating medication treatment beyond detoxification. Medical and combination interventions that focused on initiating medications for OUD generally performed well, as did psychological interventions with one or more reinforcement-based components.

CONCLUSIONS

Research efforts to improve post-detoxification outcomes would benefit from clearer reporting of sample characteristics that are associated with treatment and recovery outcomes, including diagnostic comorbidities. Findings also support the need to identify ways to introduce medication for opioid use disorder (MOUD) and other effective treatments including reinforcement-based interventions during detoxification or soon after.

Using Named Entity Recognition to Identify Substances Used in the Self-medication of Opioid Withdrawal: Natural Language Processing Study of Reddit Data

BACKGROUND

The cessation of opioid use can cause withdrawal symptoms. People often continue opioid misuse to avoid these symptoms. Many people who use opioids self-treat withdrawal symptoms with a range of substances. Little is known about the substances that people use or their effects.

OBJECTIVE

The aim of this study is to validate a methodology for identifying the substances used to treat symptoms of opioid withdrawal by a community of people who use opioids on the social media site Reddit.

METHODS

We developed a named entity recognition model to extract substances and effects from nearly 4 million comments from the r/opiates and r/OpiatesRecovery subreddits. To identify effects that are symptoms of opioid withdrawal and substances that are potential remedies for these symptoms, we deduplicated substances and effects by using clustering and manual review, then built a network of substance and effect co-occurrence. For each of the 16 effects identified as symptoms of opioid withdrawal in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, we identified the 10 most strongly associated substances. We classified these pairs as follows: substance is a Food and Drug Administration-approved or commonly used treatment for the symptom, substance is not often used to treat the symptom but could be potentially useful given its pharmacological profile, substance is a home or natural remedy for the symptom, substance can cause the symptom, or other or unclear. We developed the Withdrawal Remedy Explorer application to facilitate the further exploration of the data.

RESULTS

Our named entity recognition model achieved F1 scores of 92.1 (substances) and 81.7 (effects) on hold-out data. We identified 458 unique substances and 235 unique effects. Of the 130 potential remedies strongly associated with withdrawal symptoms, 54 (41.5%) were Food and Drug Administration-approved or commonly used treatments for the symptom, 17 (13.1%) were not often used to treat the symptom but could be potentially useful given their pharmacological profile, 13 (10%) were natural or home remedies, 7 (5.4%) were causes of the symptom, and 39 (30%) were other or unclear. We identified both potentially promising remedies (eg, gabapentin for body aches) and potentially common but harmful remedies (eg, antihistamines for restless leg syndrome).

CONCLUSIONS

Many of the withdrawal remedies discussed by Reddit users are either clinically proven or potentially useful. These results suggest that this methodology is a valid way to study the self-treatment behavior of a web-based community of people who use opioids. Our Withdrawal Remedy Explorer application provides a platform for using these data for pharmacovigilance, the identification of new treatments, and the better understanding of the needs of people undergoing opioid withdrawal. Furthermore, this approach could be applied to many other disease states for which people self-manage their symptoms and discuss their experiences on the web.

Effectiveness of non-opioid interventions to reduce opioid withdrawal symptoms in patients with chronic pain: a systematic review

BACKGROUND

Dealing with the opioid crisis, medical doctors are keen to learn how to best treat opioid dependency in patients with chronic non-cancer pain. Opioid replacement therapy is commonly used, but success rates vary widely. Since many patients still experience severe withdrawal symptoms, additional interventions are necessary.

OBJECTIVE

To review the effectiveness of interventions in the treatment of withdrawal symptoms during opioid tapering or acute withdrawal in patients with long-term non-cancer pain.

METHODS

A systematic review was conducted in Embase.com, MEDLINE, Web of Science, PsycINFO, and Cochrane CENTRAL register of trials. Studies eligible for inclusion were (non-)randomized controlled trials in adults with long-term opioid prescriptions for non-cancer pain. Included trials had to compare a non-opioid intervention to placebo, usual care, no treatment, or non-opioid drug and had to report on withdrawal symptoms as an outcome. Study quality was assessed with the 2.0 Cochrane risk of bias (RoB) tool. Evidence quality was rated following the GRADE approach.

RESULTS

One trial (n = 21, some concerns regarding RoB) compared Varenicline to placebo. There was no statistically significant between-group reduction of withdrawal symptoms (moderate-quality evidence).

CONCLUSIONS

Evidence from clinical trials on interventions reducing withdrawal symptoms is scarce. Based on one trial with a small sample size, no firm conclusion can be drawn. Meanwhile, doctors are in dire need for therapeutic options to tackle withdrawal symptoms while tapering patients with prescription opioid dependence. We hope this review draws attention to this unfortunate research gap so that future research can provide doctors with answers.

Mobile Narcotic Treatment Programs: On the Road Again?

Many Americans with opioid use disorder (OUD), do not have access to treatment. Mobile narcotic treatment programs are now under new regulations that may make treatment more accessible to more people. These mobile programs can help expand the reach of opioid agonist treatment for OUD, help reduce human immunodeficiency viruses (HIV) and hepatitis C in the OUD population, and have retention rates that are often better than those at fixed-site clinics. Mobile services can also help reach marginalized individuals, the homeless, rural communities, and other underserved communities. They may offer methadone or buprenorphine treatment. Such mobile services have been used inside and outside the United States with promising results. In particular, mobile programs can make treatment available to people who do not have insurance, who lack reliable transportation, live in chaotic situations, or may be undomiciled. The potential pairing of mobile programs together with technology, such as smartphone apps or online resources, may allow mobile patients to benefit from counseling as well. Mobile clinics must be attached to a fixed-site narcotic treatment program and may have limitations with respect to the geographic area served. Mobile programs must have policies and procedures to store, transport, deliver, account for, reconcile, and dispose of opioid waste and would be subject to audit. Mobile opioid agonist therapy is an important and innovative service of particular value to underserved communities.

Liquid chromatography-tandem mass spectrometry and confirmation by liquid chromatography-high-resolution mass spectrometry hair tests to evidence use of tizanidine by racing cyclists

Tizanidine, an imidazoline derivative close to clonidine, is a central alpha-2 adrenergic receptor agonist. Therapeutically, the drug is used as a muscle relaxant under the trade names Sirdalud™ or Zanaflex™. The drug is not prohibited by the World Anti-Doping Agency but, for therapeutic purposes, can only be obtained via a nominative temporary use authorization. The French public health police requested the laboratory to test for tizanidine in head hair specimens collected from international racing cyclists. Using Liquid chromatography-tandem mass spectrometry (LC/MS-MS) and confirmation by liquid chromatography-high-resolution mass spectrometry (LC/HRMS), after pH 9.5 borate buffer overnight incubation of 20 mg and subsequent solvents extraction, tizanidine was identified in the hair of three athletes at 1.1, 3.7, and 11.1 pg/mg. This is the first evidence that tizanidine is incorporated in human hair. However, it was not possible to interpret the data in terms of doses and frequency of use due to a lack of controlled study.

CpH methylome analysis in human cortical neurons identifies novel gene pathways and drug targets for opioid use disorder

INTRODUCTION

DNA methylation (DNAm), an epigenetic mechanism, has been associated with opioid use disorder (OUD) in preclinical and human studies. However, most of the studies have focused on DNAm at CpG sites. DNAm at non-CpG sites (mCpHs, where H indicates A, T, or C) has been recently shown to have a role in gene regulation and to be highly abundant in neurons. However, its role in OUD is unknown. This work aims to evaluate mCpHs in the human postmortem orbital frontal cortex (OFC) in the context of OUD.

METHODS

A total of 38 Postmortem OFC samples were obtained from the VA Brain Bank (OUD = 12; Control = 26). mCpHs were assessed using reduced representation oxidative bisulfite sequencing in neuronal nuclei. Differential analysis was performed using the "methylkit" R package. Age, ancestry, postmortem interval, PTSD, and smoking status were included as covariates. Significant mCpHs were set at q-value < 0.05. Gene Ontology (GO) and KEGG enrichment analyses were performed for the annotated genes of all differential mCpH loci using String, ShinyGO, and amiGO software. Further, all annotated genes were analyzed using the Drug gene interaction database (DGIdb).

RESULTS

A total of 2,352 differentially methylated genome-wide significant mCpHs were identified in OUD, mapping to 2,081 genes. GO analysis of genes with differential mCpH loci showed enrichment for nervous system development (p-value = 2.32E-19). KEGG enrichment analysis identified axon guidance and glutamatergic synapse (FDR 9E-4-2.1E-2). Drug interaction analysis found 3,420 interactions between the annotated genes and drugs, identifying interactions with 15 opioid-related drugs, including lofexidine and tizanidine, both previously used for the treatment of OUD-related symptoms.

CONCLUSION

Our findings suggest a role of mCpHs for OUD in cortical neurons and reveal important biological pathways and drug targets associated with the disorder.

How Do We Taper and Discontinue Opioids in Cancer Patients? Considerations from the Activities of a Palliative Care Team at a University Hospital

Background: The more the cancer treatments progress, the more the needs increase to taper and discontinue opioids in cancer patients. Furthermore, opioid dependence of cancer survivors has become a bigger problem. However, a safe opioid tapering and discontinuation method has not yet been established in cancer patients.

Objective: To suggest a safe opioid tapering and discontinuation method in cancer patients.

Design: We reviewed opioid type, dose, administration route, administration duration, reason for tapering and discontinuation, and presence/absence of opioid withdrawal symptoms in cancer patients whose opioids needed to be tapered and discontinued.

Setting/Subjects: We recruited cancer patients referred to the palliative care team of Kyoto University Hospital-Japan whose opioids were tapered and discontinued.

Measurements: Opioid withdrawal symptoms were assessed by two physicians, one nurse, and one pharmacist of palliative care team.

Results: Opioids were tapered and discontinued in 25 out of 145 cancer patients (17%). Opioid withdrawal symptoms were observed in 3 of the 25 cases (12%). In withdrawal symptom cases and nonwithdrawal symptom cases, the mean maximum oral morphine-equivalent doses of opioids were 352.0 and 55.7 mg/day, and the mean administration duration of opioid were 82.3 and 28.7 days, respectively. Withdrawal symptoms occurred in patients receiving higher-dose opioids with longer administration duration and their symptoms tended to appear at approximately 10% of the maximum dose.

Conclusions: We suggest that withdrawal symptoms may be prevented by using a two-stage method rather than a monotonous tapering method in cancer patients whose higher-dose opioid with longer administration duration needed to be tapered and discontinued.

Complex Interactions Between Sex and Stress on Heroin Seeking

Rationale: Stress plays a dual role in substance use disorders as a precursor to drug intake and a relapse precipitant. With heroin use at epidemic proportions in the United States, understanding interactions between stress disorders and opioid use disorder is vital and will aid in treatment of these frequently comorbid conditions. Objectives: Here, we combine assays of stress and contingent heroin self-administration (SA) to study behavioral adaptations in response to stress and heroin associated cues in male and female rats. Methods: Rats underwent acute restraint stress paired with an odor stimulus and heroin SA for subsequent analysis of stress and heroin cue reactivity. Lofexidine was administered during heroin SA and reinstatement testing to evaluate its therapeutic potential. Rats also underwent tests on the elevated plus maze, locomotor activity in a novel environment, and object recognition memory following stress and/or heroin. Results: A history of stress and heroin resulted in disrupted behavior on multiple levels. Stress rats avoided the stress conditioned stimulus and reinstated heroin seeking in response to it, with males reinstating to a greater extent than females. Lofexidine decreased heroin intake, reinstatement, and motor activity. Previous heroin exposure increased time spent in the closed arms of an elevated plus maze, activity in a round novel field, and resulted in object recognition memory deficits. Discussion: These studies report that a history of stress and heroin results in maladaptive coping strategies and suggests a need for future studies seeking to understand circuits recruited in this pathology and eventually help develop therapeutic approaches.

Pain Management Considerations in Patients with Opioid Use Disorder Requiring Critical Care

The opioid epidemic has resulted in increased opioid-related critical care admissions, presenting challenges in acute pain management. Limited guidance exists in the management of critically ill patients with opioid use disorder (OUD). This narrative review provides the intensive care unit (ICU) clinician with guidance and treatment options, including non-opioid analgesia, for patients receiving medications for opioid use disorder (MOUD) and for patients actively misusing opioids. Verification and continuation of the patient's outpatient MOUD regimen, specifically buprenorphine and methadone formulations, assessment of pain and opioid withdrawal, and treatment of acute pain with non-opioid analgesia, nonpharmacologic strategies, and short-acting opioids as needed, are all essential to adequate management of acute pain in patients with OUD. A multidisciplinary approach to treatment and discharge planning in patients with OUD may be beneficial to engage patients with OUD early in their hospital stay to prevent withdrawal, stabilize their OUD, and to reduce the risk of unplanned discharge and other associated morbidity. This article is protected by copyright. All rights reserved.

How to Manage Withdrawal of Sedation and Analgesia in Mechanically Ventilated COVID-19 Patients?

COVID-19 patients suffering from severe acute respiratory distress syndrome (ARDS) require mechanical ventilation (MV) for respiratory failure. To achieve these ventilatory goals, it has been observed that COVID-19 patients in particular require high regimens and prolonged use of sedatives, analgesics and neuromuscular blocking agents (NMBA). Withdrawal from analgo-sedation may induce a "drug withdrawal syndrome" (DWS), i.e., clinical symptoms of anxiety, tremor, agitation, hallucinations and vomiting, as a result of adrenergic activation and hyperalgesia. We describe the epidemiology, mechanisms leading to this syndrome and our strategies to prevent and treat it.

Drug repurposing for opioid use disorders: integration of computational prediction, clinical corroboration, and mechanism of action analyses

Morbidity and mortality from opioid use disorders (OUD) and other substance use disorders (SUD) is a major public health crisis, yet there are few medications to treat them. There is an urgency to accelerate SUD medication development. We present an integrated drug repurposing strategy that combines computational prediction, clinical corroboration using electronic health records (EHRs) of over 72.9 million patients and mechanisms of action analysis. Among top-ranked repurposed candidate drugs, tramadol, olanzapine, mirtazapine, bupropion, and atomoxetine were associated with increased odds of OUD remission (adjusted odds ratio: 1.51 [1.38-1.66], 1.90 [1.66-2.18], 1.38 [1.31-1.46], 1.37 [1.29-1.46], 1.48 [1.25-1.76], p value < 0.001, respectively). Genetic and functional analyses showed these five candidate drugs directly target multiple OUD-associated genes including BDNF, CYP2D6, OPRD1, OPRK1, OPRM1, HTR1B, POMC, SLC6A4 and OUD-associated pathways, including opioid signaling, G-protein activation, serotonin receptors, and GPCR signaling. In summary, we developed an integrated drug repurposing approach and identified five repurposed candidate drugs that might be of value for treating OUD patients, including those suffering from comorbid conditions.

Validation and characterization of oxycodone physical dependence in C57BL/6J mice

Opioid use disorder is a growing concern in the United States. Mice were used to investigate the mechanisms involving opioid physical dependence and for evaluating medications for treating opioid use disorders. While there are many preclinical reports describing protocols for inducing physical dependence upon morphine, there are fewer preclinical reports describing more contemporary abused prescription opiates. The goal of this study was to characterize and validate a mouse model of oxycodone dependence. Male C57BL/6J mice were injected with saline or increasing doses of oxycodone (9-33 mg/kg) twice daily for 8 days. On the 9th day, mice were challenged with 1 mg/kg naloxone and observed for somatic signs. Mice were pretreated with oxycodone (17, 33, or 75 mg/kg) prior to withdrawal to determine if it could attenuate somatic withdrawal signs. Additional mouse groups were pretreated with 1 mg/kg clonidine. Lastly, we measured somatic signs for 6, 24, and 48 h post-withdrawal during spontaneous and precipitated withdrawal. Pretreating with oxycodone or clonidine dose-dependently prevented the emergence of withdrawal signs. Mice chronically treated with oxycodone exhibited more withdrawal signs than vehicle at 24 h after the final injection during spontaneous withdrawal. In contrast, mice that received repeated naloxone challenges showed peak withdrawal signs at 6 h, and withdrawal signs were significantly greater at all time points compared to vehicle. Reversal of withdrawal effects by positive controls, and establishing spontaneous and precipitated withdrawal paradigms, serve as validation of this model and provide a means to examine novel therapeutics to treat opioid withdrawal.