Safety, tolerability, and clinical effect of low-dose buprenorphine for treatment-resistant depression in midlife and older adults

Buprenorphine for the Treatment of Military-related PTSD With Treatment-resistant Depression and Unexpected Benefit for Chronic Pain: Case Report

The prevalence of treatment-resistant depression within global and military populations highlights the need for novel treatment approaches beyond monoamine neurotransmitter modulators. Buprenorphine (BUP), a semi-synthetic partial opioid agonist, is approved for the treatment of opioid use disorder and has shown promise in treating both depression and chronic pain. This case report discusses the use of transdermal BUP in treating a 36 year-old man with treatment-resistant depression with prominent anhedonia, military-related posttraumatic stress disorder, and chronic pain because of barosinusitis. Significant reductions in anxious and depressive symptoms, including in anhedonia, were observed with lasting effects. An unexpected finding was the discontinuation of prescribed hydromorphone for pain, suggesting the potential unique benefit of BUP in treating chronic pain and treatment resistant depression comorbidities. These findings implicate the diverse beneficial potential of BUP in psychiatric treatments for military populations.

Trends in Outpatient Buprenorphine Prescribing for Chronic Pain: A Retrospective Analysis Over 18 Months

Background

Buprenorphine, a partial opioid agonist, has gained attention for its use in chronic pain management due to its lower risk of abuse and respiratory depression compared to traditional opioids. The utilization of buprenorphine for chronic pain has increased in recent years. This study aimed to analyze trends in buprenorphine prescribing for chronic pain in an outpatient setting over an 18-month period, excluding buprenorphine-naloxone combinations used for opioid use disorder and opioid dependence.

Methods

A retrospective chart review was conducted, examining outpatient buprenorphine and long-acting opioid prescriptions issued by three pain management physicians between January 1, 2023, and June 30, 2024. Prescription data were collected from electronic medical records (EMRs) and analyzed across three six-month intervals: January 1, 2023, to June 30, 2023; July 1, 2023, to December 31, 2023; and January 1, 2024, to June 30, 2024. Only unique buprenorphine prescriptions for chronic pain management were included, while buprenorphine-naloxone prescriptions for opioid use disorder were excluded. Long-acting opioids analyzed included extended release (ER) formulations including tramadol ER, morphine ER, hydrocodone ER, oxycodone ER, fentanyl, and methadone.

Results

Over the 18-month study period, a total of 61 unique buprenorphine prescriptions for chronic pain were issued by the three physicians. The number of prescriptions increased across each six-month period: 18 prescriptions were issued between January 1, 2023, and June 30, 2023; 20 prescriptions from July 1, 2023, to December 31, 2023; and 23 prescriptions from January 1, 2024, to June 30, 2024. This represents a 27.8% increase over the entire 18-month period. During the same timeframe, 117 long-acting opioid prescriptions (excluding buprenorphine) were issued in the first six-month period, 121 prescriptions in the second period, and 108 prescriptions in the third period. Buprenorphine prescriptions accounted for 13.3% of all long-acting opioid prescriptions in the first period (18 out of 135 total prescriptions), 14.2% in the second period (20 out of 141 total prescriptions), and 17.6% in the third period (23 out of 131 total prescriptions). Notably, while the absolute number of buprenorphine prescriptions increased steadily, its proportion relative to total long-acting opioid prescriptions also grew over time.

Conclusions

The findings demonstrate a steady increase in buprenorphine prescribing for chronic pain in the outpatient setting, while long-acting opioid prescriptions exhibited a slight decline in the later periods. The proportion of buprenorphine prescriptions relative to long-acting opioids increased over time, suggesting growing acceptance of buprenorphine as a safer alternative for chronic pain management. Further research is needed to explore the factors driving these prescribing patterns and the long-term clinical outcomes associated with buprenorphine use in chronic pain management.

Evaluating the Impact of Buprenorphine on Depressive Symptoms Among Veterans with Chronic Pain

Buprenorphine has demonstrated benefit for acute and chronic pain and various psychiatric disorders. However, many studies evaluating buprenorphine's effect on psychiatric conditions are not specific to the chronic pain population. This retrospective study was conducted to assess the impact of buprenorphine on depressive symptoms in patients with chronic pain at a Veterans Affairs healthcare facility. Adults with chronic pain started on any formulation of buprenorphine or traditional opioid (non-buprenorphine opioid) with at least two depression screenings between May 1, 2016 and November 1, 2021 were included. The primary outcome was change in depressive symptoms, measured by Patient Health Questionnaire-9 (PHQ-9), from baseline to 6-18 months after starting therapy. Secondary outcomes included changes in Columbia-Suicide Severity Rating Scale and mental health services utilization. Twenty-one patients were included. Median baseline PHQ-9 in the buprenorphine and traditional opioid groups were 14 and 13, respectively. Median change in PHQ-9 was -5 in the buprenorphine group and -1.5 in the traditional opioid group. Compared to traditional opioids, buprenorphine was associated with a greater reduction in depressive symptoms among Veterans with chronic pain. Although this reduction met the threshold for clinically significant improvement, further investigation is needed to evaluate the clinical relevance of these findings.

IUPHAR review: Drug repurposing in Schizophrenia - An updated review of clinical trials

There is an urgent need for mechanistically novel and more efficacious treatments for schizophrenia, especially those targeting negative and cognitive symptoms with a more favorable side-effect profile. Drug repurposing-the process of identifying new therapeutic uses for already approved compounds-offers a promising approach to overcoming the lengthy, costly, and high-risk process of traditional CNS drug discovery. This review aims to update our previous findings on the clinical drug repurposing pipeline in schizophrenia. We examined studies conducted between 2018 and 2024, identifying 61 trials evaluating 40 unique repurposed drug candidates. These encompassed a broad range of pharmacological mechanisms, including immunomodulation, cognitive enhancement, and hormonal, metabolic, and neurotransmitter modulation. A notable development is the combination of the muscarinic modulators xanomeline, a compound with antipsychotic properties, and trospium, included to mitigate peripheral side effects, now approved by the FDA as the first antipsychotic drug in decades with a fundamentally novel mechanism of action. Moving beyond the traditional dopaminergic paradigm of schizophrenia, such findings highlight opportunities to improve treatment-resistant symptoms and alleviate adverse effects. Overall, the evolving drug repurposing landscape illustrates a significant shift in the rationale for schizophrenia drug development, highlighting the potential of in silico strategies, biomarker-based patient stratification, and personalized treatments that align with underlying pathophysiological processes.

Safety in treatment: Classical pharmacotherapeutics and new avenues for addressing maternal depression and anxiety during pregnancy

We aimed to review clinical research on the safety profiles of antidepressant drugs and associations with maternal depression and neonatal outcomes. We focused on neuroendocrine changes during pregnancy and their effects on antidepressant pharmacokinetics. Pregnancy-induced alterations in drug disposition and metabolism impacting mothers and their fetuses are discussed. We considered evidence for the risks of antidepressant use during pregnancy. Teratogenicity associated with ongoing treatment, new prescriptions during pregnancy, or pausing medication while pregnant was examined. The Food and Drug Administration advises caution regarding prenatal exposure to most drugs, including antidepressants, largely owing to a dearth of safety studies caused by the common exclusion of pregnant individuals in clinical trials. We contrasted findings on antidepressant use with the lack of treatment where detrimental effects to mothers and children are well researched. Overall, drug classes such as selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors appear to have limited adverse effects on fetal health and child development. In the face of an increasing prevalence of major mood and anxiety disorders, we assert that individuals should be counseled before and during pregnancy about the risks and benefits of antidepressant treatment given that withholding treatment has possible negative outcomes. Moreover, newer therapeutics, such as ketamine and κ-opioid receptor antagonists, warrant further investigation for use during pregnancy. SIGNIFICANCE STATEMENT: The safety of antidepressant use during pregnancy remains controversial owing to an incomplete understanding of how drug exposure affects fetal development, brain maturation, and behavior in offspring. This leaves pregnant people especially vulnerable, as pregnancy can be a highly stressful experience for many individuals, with stress being the biggest known risk factor for developing a mood or anxiety disorder. This review focuses on perinatal pharmacotherapy for treating mood and anxiety disorders, highlighting the current knowledge and gaps in our understanding of consequences of treatment.

Emerging Medications for Treatment-Resistant Depression: A Review with Perspective on Mechanisms and Challenges

Background/Objectives: Non-response to initial treatment options for major depressive disorder (MDD) is a common clinical challenge with profound deleterious impacts for affected patients. Few treatments have received regulatory approval for treatment-resistant depression (TRD). Methods: A systematic search of United States and European Union clinical trials registries was conducted to identify Phase II, III, or IV clinical trials, with a last update posted on or after 1 January 2020, that were evaluating medications for TRD. For both the US and EU registries, the condition term "treatment resistant depression" and associated lower-level terms (per registry search protocol) were used. For the US registry, a secondary search using the condition term "depressive disorders" and the modifying term "inadequate" was also performed to capture registrations not tagged as TRD. Two additional searches were also conducted in the US registry for the terms "suicide" and "anhedonia" as transdiagnostic targets of investigational medications. Trials were categorized based on the primary mechanism of action of the trial's investigational medication. Results: Fifty clinical trials for TRD, 20 for anhedonia, and 25 for suicide were identified. Glutamate system modulation was the mechanism currently with the most compounds in development, including antagonists and allosteric modulators of NMDA receptors, AMPA receptors, metabotropic type 2/3 glutamate receptors, and intracellular effector molecules downstream of glutamate signaling. Psychedelics have seen the greatest surge among mechanistic targets in the past 5 years, however, with psilocybin in particular garnering significant attention. Other mechanisms included GABA modulators, monoamine modulators, anti-inflammatory/immune-modulating agents, and an orexin type 2 receptor antagonist. Conclusions: These investigations offer substantial promise for more efficacious and potentially personalized medication approaches for TRD. Challenges for detecting efficacy in TRD include the heterogeneity within the TRD population stemming from the presumed variety of biological dysfunctions underlying the disorder, comorbid disorders, chronic psychosocial stressors, and enduring effects of prior serotonergic antidepressant medication treatments.

Is buprenorphine maternal dose associated with neonatal opioid withdrawal syndrome severity?

BACKGROUND

Neonatal opioid withdrawal syndrome (NOWS) is a drug withdrawal syndrome occurring mainly after in utero opioid exposure. Buprenorphine is commonly used for opioid withdrawal. Studies are conflicted about a potential dose effect OBJECTIVE: The aim of our study was to investigate the impact of buprenorphine maternal maintenance therapy on the NOWS based on NOWS duration, birth weight and therapy.

STUDY DESIGN

We conducted a retrospective study analysing data from infants admitted for NOWS in two Neonatal Intensive Care Unit between January 2010 and December 2020.

INCLUSION CRITERIA

Nonpreterm infants born to mothers who were treated with buprenorphine or therapy during pregnancy and who had a Lipsitz score of 4 or higher.

RESULTS

A total of 75 term newborns were hospitalized for the treatment of NOWS from mother substituted with buprenorphine during the study inclusion period. The duration of NOWS differed significantly between all dose cohorts, with higher doses of maternal buprenorphine maintenance correlating with longer length of NOWS duration. Infants exposed to high doses required 17 days [10; 23], while infants exposed to intermediate doses required 7 days [2; 16] and infants exposed to low doses required 3 days [2; 5], with p-values < .003. Infants exposed to high doses required a longer time to regain their birth weight and higher morphine doses as therapy compared to others. Infants exposed to low doses, intermediate doses, and high doses of buprenorphine demonstrated dose-dependent increases in the durations of hospitalization, respectively.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Increased doses of maternal buprenorphine during pregnancy are correlated with NOWS severity. Our study shows that increased doses of maternal buprenorphine during pregnancy are correlated with NOWS severity. Exploring low doses and having different ranges are a new argument to define the impact of maternal buprenorphine consumption.

Pharmacological Strategies to Decrease Long-Term Prescription Opioid Use: A Systematic Review

Background/Objectives: As long-term prescription opioid use is associated with increased morbidity and mortality, timely dose reduction of prescription opioids should be considered. However, most research has been conducted on patients using heroin. Given the differences between prescription and illicit opioid use, the aim of this review was to provide an overview of pharmacological strategies to reduce prescription opioid use or improve clinical outcomes for people who experience long-term prescription opioid use, including those with opioid use disorder. Methods: We conducted a systematic database search of PubMed, Embase, CINAHL, and the Cochrane Library. Outcomes included dose reduction, treatment dropout, pain, addiction, and outcomes relating to quality of life (depression, functioning, quality of life). Results: We identified thirteen studies (eight randomized controlled trials and five observational studies). Pharmacological strategies were categorized into two categories: (1) deprescribing (tapering) opioids or (2) opioid agonist treatment (OAT) with long-acting opioids. Tapering strategies decreased opioid dosage and had mixed effects on pain and addiction. OAT with buprenorphine or methadone led to improvements in pain relief and quality of life, with a slight (non-significant) preference for methadone in terms of treatment retention (RR = 1.10 [CI: 0.89-1.37]) but not for other outcomes. Most studies had high dropout rates and a serious risk of bias. Conclusions: Tapering reduced prescription opioid doses had mixed effects on pain. OAT improved clinical outcomes without dose reduction. Based on our review findings, there is no clear preference for either tapering or OAT. Tapering may be considered first as it reduces dependency, tolerance, and side effects, but is associated with adverse events and not always feasible. OAT can be a suitable alternative. Non-pharmacological interventions may facilitate tapering. Further research is needed to identify novel pharmacological strategies to facilitate opioid tapering. Registration: PROSPERO 2022 CRD42022323468.

Brain region-specific neural activation by low-dose opioid promotes social behavior

The opioid system plays crucial roles in modulating social behaviors in both humans and animals. However, the pharmacological profiles of opioids regarding social behavior and their therapeutic potential remain unclear. Multiple pharmacological, behavioral, and immunohistological c-Fos mapping approaches were used to characterize the effects of μ-opioid receptor agonists on social behavior and investigate the mechanisms in naive mice and autism spectrum disorder-like (ASD-like) mouse models, such as prenatally valproic acid-treated mice and Fmr1-KO mice. Here, we report that low-dose morphine, a μ-opioid receptor agonist, promoted social behavior by selectively activating neurons in prosocial brain regions, including the nucleus accumbens, but not those in the dorsomedial periaqueductal gray (dmPAG), which are only activated by analgesic high-dose morphine. Critically, intra-dmPAG morphine injection counteracted the prosocial effect of low-dose morphine, suggesting that dmPAG neural activation suppresses social behavior. Moreover, buprenorphine, a μ-opioid receptor partial agonist with less abuse liability and a well-established safety profile, ameliorated social behavior deficits in two mouse models recapitulating ASD symptoms by selectively activating prosocial brain regions without dmPAG neural activation. Our findings highlight the therapeutic potential of brain region-specific neural activation induced by low-dose opioids for social behavior deficits in ASD.

Therapeutic Potential of Buprenorphine in Depression: A Meta-Analysis of Current Evidence

BACKGROUND

Emerging research indicates buprenorphine, used in management of opioid use disorder, has attracted interest for its potential in treating a variety of psychiatric conditions. This meta-analysis aimed to determine the efficacy of buprenorphine in treating symptoms of depression.

METHODS

Using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, a search was conducted of several databases until April 25, 2022, for English language articles related to buprenorphine and its use in treating various mental health conditions. Standardized mean differences (SMDs) and its 95% confidence intervals (CIs) were reported for the Hamilton Rating Scale for Depression (HAM-D) and the Montgomery-Asberg Depression Rating Scale (MADRS) scores. Statistical analyses were performed using Cochrane RevMan 5.

RESULTS

Of the 1,347 identified studies, six clinical trials were included. MADRS-10 least square mean difference (LSMD) inter-group assessment favored buprenorphine over placebo, but it lacked statistical significance. Similarly, MADRS scores as well as HAM-D inter-group assessment were in favor of buprenorphine, however, were not statistically significant. These findings suggest a potential therapeutic role for buprenorphine in treating depression, albeit with caution due to the observed lack of statistical significance and the potential for confounding factors.

CONCLUSIONS

Preliminary evidence suggests potential efficacy of buprenorphine at lower doses in improving improving outcomes specifically related to depression. However, due to limitations in statistical significance and possible confounding factors, entail cautious interpretation. Further rigorous research is needed to investigate the long-term effects, optimal dosing, and determine the role of adjuvant drug therapy.

Converged avenues: depression and Alzheimer's disease- shared pathophysiology and novel therapeutics

Depression, a highly prevalent disorder affecting over 280 million people worldwide, is comorbid with many neurological disorders, particularly Alzheimer's disease (AD). Depression and AD share overlapping pathophysiology, and the search for accountable biological substrates made it an essential and intriguing field of research. The paper outlines the neurobiological pathways coinciding with depression and AD, including neurotrophin signalling, the hypothalamic-pituitary-adrenal axis (HPA), cellular apoptosis, neuroinflammation, and other aetiological factors. Understanding overlapping pathways is crucial in identifying common pathophysiological substrates that can be targeted for effective management of disease state. Antidepressants, particularly monoaminergic drugs (first-line therapy), are shown to have modest or no clinical benefits. Regardless of the ineffectiveness of conventional antidepressants, these drugs remain the mainstay for treating depressive symptoms in AD. To overcome the ineffectiveness of traditional pharmacological agents in treating comorbid conditions, a novel therapeutic class has been discussed in the paper. This includes neurotransmitter modulators, glutamatergic system modulators, mitochondrial modulators, antioxidant agents, HPA axis targeted therapy, inflammatory system targeted therapy, neurogenesis targeted therapy, repurposed anti-diabetic agents, and others. The primary clinical challenge is the development of therapeutic agents and the effective diagnosis of the comorbid condition for which no specific diagnosable scale is present. Hence, introducing Artificial Intelligence (AI) into the healthcare system is revolutionary. AI implemented with interdisciplinary strategies (neuroimaging, EEG, molecular biomarkers) bound to have accurate clinical interpretation of symptoms. Moreover, AI has the potential to forecast neurodegenerative and psychiatric illness much in advance before visible/observable clinical symptoms get precipitated.

Opioid Mechanisms and the Treatment of Depression

Opioid receptors are widely expressed in the brain, and the opioid system has a key role in modulating mood, reward processing and stress responsivity. There is mounting evidence that the endogenous opioid system may be dysregulated in depression and that drug treatments targeting mu, delta and kappa opioid receptors may show antidepressant potential. The mechanisms underlying the therapeutic effects of opioid system engagement are complex and likely multi-factorial. This chapter explores various pathways through which the modulation of the opioid system may influence depression. These include impacts on monoaminergic systems, the regulation of stress and the hypothalamic-pituitary-adrenal axis, the immune system and inflammation, brain-derived neurotrophic factors, neurogenesis and neuroplasticity, social pain and social reward, as well as expectancy and placebo effects. A greater understanding of the diverse mechanisms through which opioid system modulation may improve depressive symptoms could ultimately aid in the development of safe and effective alternative treatments for individuals with difficult-to-treat depression.

Buprenorphine for Chronic Pain Management: a Narrative Review

PURPOSE OF REVIEW

The aim of this review is to educate healthcare professionals regarding buprenorphine for the use of opioid use disorder (OUD) as well as for chronic pain management. This review provides physicians and practitioners with updated information regarding the distinct characteristics and intricacies of prescribing buprenorphine.

RECENT FINDINGS

Buprenorphine is approved by the US Food and Drug Administration (FDA) for acute pain, chronic pain, opioid use disorder (OUD), and opioid dependence. When compared to most other opioids, buprenorphine offers superior patient tolerability, an excellent half-life, and minimal respiratory depression. Buprenorphine does have notable side effects as well as pharmacokinetic properties that require special attention, especially if patients require future surgical interventions. Many physicians are not trained to initiate or manage patients on buprenorphine. However, buprenorphine offers a potentially safer alternative for medication management for patients who require chronic opioid therapy for pain or have OUD. This review provides updated information on buprenorphine for both chronic pain and OUD.

Quality of life and associated factors of heroin-dependent patients receiving methadone and buprenorphine maintenance treatment

AIM

Although studies in Western countries have investigated the quality of life (QoL) of heroin users, limited research on this topic has been conducted in Asia. The present study assessed QoL in patients with heroin dependence receiving medications to treat opioid use disorder.

METHODS

We performed a cross-sectional study of patients with heroin dependence receiving methadone and buprenorphine treatment. The demographic and substance use variables of patients receiving methadone and buprenorphine were compared. The Chinese Health Questionnaire (CHQ-12), Obsessive Compulsive Drug Use Scale (OCDUS), and World Health Organization Quality of Life Short Form Taiwan version (WHOQOL-BREF-T) were administered to measure patient mental health problems, addiction severity, and QoL, respectively. Multivariate regression was used to identify the factors associated with QoL.

RESULTS

A total of 149 patients receiving methadone and 31 receiving buprenorphine completed the questionnaires. Individuals in the buprenorphine group were more likely to be married (p = 0.024) or employed (p = 0.024), have a higher educational level (p = 0.013), have lower drug craving (OCDUS: p = 0.035), or have higher QoL (WHOQOL-BREF-T: p = 0.004) than those in the methadone group. After adjustment for other variables, employment was positively associated with the physical, psychological, and environmental domains of QoL. Receiving buprenorphine treatment (p = 0.032) and longer treatment duration (p = 0.016) were associated with higher psychological QoL.

CONCLUSION

Several factors were associated with QoL in patients with heroin dependence. Some measures may improve their QoL, such as reducing employment barriers, improving treatment adherence, or increasing accessibility to buprenorphine treatment.

A synopsis of multitarget therapeutic effects of anesthetics on depression

Depression is a profound mental disorder that dampens the mood and undermines volition, which exhibited an increased incidence over the years. Although drug-based interventions remain the primary approach for depression treatment, the available medications still can't satisfy the patients. In recent years, the newly discovered therapeutic targets such as N-methyl-D-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor, and tyrosine kinase B (TrkB) have brought new breakthroughs in the development of antidepressant drugs. Moreover, it has come to light that certain anesthetics possess pharmacological mechanisms intricately linked to the aforementioned therapeutic targets for depression. At present, numerous preclinical and clinical studies have explored the therapeutic effects of anesthetic drugs such as ketamine, isoflurane, N2O, and propofol, on depression. These investigations suggested that these drugs can swiftly ameliorate patients' depression symptoms and engender long-term effects. In this paper, we provide a comprehensive review of the research progress and potential molecular mechanisms of various anesthetic drugs for depression treatment. By shedding light on this subject, we aim to facilitate the development and clinical implementation of new antidepressant drugs based on anesthetic medications.

A Review of Therapeutics for Treatment-Resistant Depression in the Older Adult

One-third of older adults with depression meet criteria for treatment resistance, typically defined as a lack of response to two or more adequate trials of an antidepressant. Treatment resistance contributes to an unfavorable prognosis, compromised medical outcomes, heightened disability, accelerated cognitive decline, and an elevated risk of developing dementia. Despite this significant morbidity, evidence is sparse for how to proceed with treatment in this population. Non-pharmacologic therapy (e.g., diet, psychotherapy) can be utilized as adjunctive therapy, despite little published evidence of benefit, given that the risks are low. Pharmacotherapy trials in the treatment-resistant late-life depression population lack strong methods and external validity; however, the use of venlafaxine as monotherapy and add-on therapy, as well as lithium, bupropion, or aripiprazole as add-on therapy to standard antidepressant therapy, have enough evidence that a trial with appropriate monitoring is a prudent strategy. Electroconvulsive therapy remains a well-studied safe therapy, especially when used as maintenance treatment once an initial cycle is completed but is traditionally underutilized in the treatment-resistant late-life depression population. Ensuring non-pharmacologic and pharmacologic strategies are optimized and given a sufficient trial in those with treatment-resistant late-life depression is the best we can do for this vulnerable population.

Effects of Buprenorphine/Naloxone and Methadone on Depressive Symptoms in People with Prescription Opioid Use Disorder: A Pragmatic Randomised Controlled Trial

OBJECTIVE

This study aimed to evaluate the effectiveness of flexible take-home dosing of buprenorphine/naloxone (BUP/NX) and methadone standard model of care in reducing depressive symptoms in people with prescription-type opioid use disorder (POUD). This trial also evaluated whether improvements in depressive symptoms were mediated by opioid use.

METHODS

Analyzed data came from the OPTIMA study (clinicaltrials.gov identifier: NCT03033732), a pragmatic randomised controlled trial comparing flexible take-home dosing of BUP/NX and methadone standard model of care for reducing opioid use in people with POUD. A total of 272 participants were recruited in four Canadian provinces. Participants were randomised 1:1 to BUP/NX or methadone. After treatment induction, past two-week opioid use was measured using the Timeline Followback every two weeks for a total of 24 weeks. Depressive symptoms were measured with the Beck Depression Inventory at baseline, weeks 12 and 24.

RESULTS

Both BUP/NX and methadone significantly reduced depressive symptoms at week 12 (aβ ± SE = -3.167 ± 1.233; P < 0.001) and week 24 (aβ ± SE = -7.280 ± 1.285; P < 0.001), with no interaction between type of treatment and time (P = 0.284). Improvements in depressive symptoms were only partially mediated by a reduction in opioid use (proportion mediated = 36.8%; 95% confidence interval = -1.158 to -0.070; P = 0.015).

CONCLUSIONS

BUP/NX and methadone showed similar effectiveness in decreasing comorbid depressive symptoms in people with POUD. This effect was partially explained by a reduction in opioid use. As both treatments seem equally effective, clinicians are encouraged to tailor the selection of OAT to patients' needs and characteristics.

Contribution of the opioid system to depression and to the therapeutic effects of classical antidepressants and ketamine

Major depressive disorder (MDD) afflicts approximately 5 % of the world population, and about 30-50 % of patients who receive classical antidepressant medications do not achieve complete remission (treatment resistant depressive patients). Emerging evidence suggests that targeting opioid receptors mu (MOP), kappa (KOP), delta (DOP), and the nociceptin/orphanin FQ receptor (NOP) may yield effective therapeutics for stress-related psychiatric disorders. As depression and pain exhibit significant overlap in their clinical manifestations and molecular mechanisms involved, it is not a surprise that opioids, historically used to alleviate pain, emerged as promising and effective therapeutic options in the treatment of depression. The opioid signaling is dysregulated in depression and numerous preclinical studies and clinical trials strongly suggest that opioid modulation can serve as either an adjuvant or even an alternative to classical monoaminergic antidepressants. Importantly, some classical antidepressants require the opioid receptor modulation to exert their antidepressant effects. Finally, ketamine, a well-known anesthetic whose extremely efficient antidepressant effects were recently discovered, was shown to mediate its antidepressant effects via the endogenous opioid system. Thus, although opioid system modulation is a promising therapeutical venue in the treatment of depression further research is warranted to fully understand the benefits and weaknesses of such approach.

Efficacy and safety of duloxetine in chronic musculoskeletal pain: a systematic review and meta-analysis

BACKGROUND

Chronic musculoskeletal pain (CMP) is a complex condition that is mainly treated with analgesic drugs. However, antidepressant intervention is also an important factor in the treatment of CMP. Duloxetine is an effective treatment option for patients with CMP as its antidepressant effect. The purpose of this article is to evaluate the efficacy and safety of duloxetine in treating CMP.

DATABASES AND DATA TREATMENT

We searched PubMed, Web of Science, Embase, Cochrane Library from inception to May, 2022. Randomized controlled trials (RCTs) evaluating the efficacy and safety of duloxetine versus placebo in patients with CMP were included. We identified 13 articles and studied a population of 4201 participants in 4 countries.

RESULTS

This meta-analysis showed that the duloxetine has statistically significant compared with the placebo control, benefits on 24-hour average pain, living quality, physical function, and global impressions and there was no difference in the incidence of serious adverse event. In general, duloxetine can improve mood and pain level at the same time.

CONCLUSIONS

This review shows a significant contribution of duloxetine to CMP symptom relief. This meta-analysis improved that duloxetine can significantly reduce the pain level of patients, improve depressive symptoms and global impression, and has no obvious serious adverse reactions. However, additional studies are required to confirm the relationship between psychological diseases and chronic pain and explore their internal links.

The switching process from buprenorphine sublingual tablets to the monthly buprenorphine subcutaneous depot injection in opioid dependent patients

The 2018 European Union (EU) approved weekly and monthly subcutaneous buprenorphine depot injection (BUP-XR), for opioid substitution medication proved to offer some specific treatment benefits. The present study examines the process of switching from buprenorphine sublingual tablets (BUP-SL) to BUP-XR from a patient's point of view. In total, nine patients were surveyed by means of an open-answer questionnaire regarding course and side effects of the medication switch. Six of these patients were surveyed in more detail under BUP-SL, as well as 4 and 16 weeks after the switch to BUP-XR by means of a test battery of questions on socio-demography, withdrawal symptoms, craving, physical well-being, treatment satisfaction and concomitant use of illegal substances. Patients reported significant worse physical well-being and lower treatment satisfaction in 4 weeks compared with 16 weeks after the medication switch to the BUP-XR. Furthermore, they reported significant more frequent co-use of illicit drugs, worse physical well-being, lower treatment satisfaction and more craving experience 4 weeks after the switch compared with the treatment under BUP-SL. Patients 16 weeks under BUP-XR reported significant more illicit co-use and lower treatment satisfaction compared with patients under BUP-SL. Connections between therapy dissatisfaction, physical discomfort, experienced craving and drug co-consumption were discovered. In the first weeks after the medication switch, patients experience potentially distressing symptoms, which, however, seem to diminish over time. Close supervision and comprehensive patient education on possible burdens of the medication switch to the BUP-XR might prevent unfavourable treatment courses and premature therapy dropouts.

The efficacy and safety of buprenorphine for the treatment of depression: A systematic review and meta-analysis

BACKGROUND

Depressive disorders are common. Many patients with major depression do not achieve remission with available treatments. Buprenorphine has been raised as a potential treatment for depression as well as suicidal behavior but may pose certain risks.

METHODS

A meta-analysis comparing the efficacy, tolerability, and safety of buprenorphine (or combinations such as buprenorphine/samidorphan) versus control in improving symptoms in patients with depression. Medline, Cochrane Database, PsycINFO, Excerpta Medica Database and The Cumulative Index to Nursing and Allied Health Literature were searched from inception through January 2, 2022. Depressive symptoms were pooled using Hedge's g with 95% Confidence Intervals (CI). Tolerability, safety, suicide outcomes were summarized qualitatively.

RESULTS

11 studies (N = 1699) met inclusion criteria. Buprenorphine had a small effect on depressive symptoms (Hedges' g 0.17, 95%CI: 0.05-0.29). Results were driven by six trials of buprenorphine/samidorphan (N = 1,343, Hedges's g 0.17, 95%CI: 0.04-0.29). One study reported significant improvement in suicidal thoughts (Least Squares Mean Change: -7.1, 95%CI: -12.0 - 2.3). Most studies found buprenorphine was well-tolerated with no evidence of abuse behavior or dependency.

CONCLUSIONS

Buprenorphine may have a small benefit for depressive symptoms. Future research should clarify the dose response relationship between buprenorphine and depression.

Changes in Psychological Outcomes after Cessation of Full Mu Agonist Long-Term Opioid Therapy for Chronic Pain

Improved understanding of psychological features associated with full mu agonist long-term opioid therapy (LTOT) cessation may offer advantages for clinicians. This preliminary study presents changes in psychological outcomes in patients with chronic, non-cancer pain (CNCP) after LTOT cessation via a 10-week multidisciplinary program which included treatment with buprenorphine. Paired t-tests pre- and post-LTOT cessation were compared in this retrospective cohort review of data from electronic medical records of 98 patients who successfully ceased LTOT between the dates of October 2017 to December 2019. Indicators of quality of life, depression, catastrophizing, and fear avoidance, as measured by the 36-Item Short Form Survey, the Patient Health Questionnaire-9-Item Scale, the Pain Catastrophizing Scale, and the Fear Avoidance Belief Questionnaires revealed significant improvement. Scores did not significantly improve for daytime sleepiness, generalized anxiety, and kinesiophobia, as measured by the Epworth Sleepiness Scale, the Generalized Anxiety Disorder 7-Item Scale, and the Tampa Scale of Kinesiophobia. The results suggest that successful LTOT cessation may be interconnected with improvements in specific psychological states.

Endogenous opioid systems alterations in pain and opioid use disorder

Decades of research advances have established a central role for endogenous opioid systems in regulating reward processing, mood, motivation, learning and memory, gastrointestinal function, and pain relief. Endogenous opioid systems are present ubiquitously throughout the central and peripheral nervous system. They are composed of four families, namely the μ (MOPR), κ (KOPR), δ (DOPR), and nociceptin/orphanin FQ (NOPR) opioid receptors systems. These receptors signal through the action of their endogenous opioid peptides β-endorphins, dynorphins, enkephalins, and nociceptins, respectfully, to maintain homeostasis under normal physiological states. Due to their prominent role in pain regulation, exogenous opioids-primarily targeting the MOPR, have been historically used in medicine as analgesics, but their ability to produce euphoric effects also present high risks for abuse. The ability of pain and opioid use to perturb endogenous opioid system function, particularly within the central nervous system, may increase the likelihood of developing opioid use disorder (OUD). Today, the opioid crisis represents a major social, economic, and public health concern. In this review, we summarize the current state of the literature on the function, expression, pharmacology, and regulation of endogenous opioid systems in pain. Additionally, we discuss the adaptations in the endogenous opioid systems upon use of exogenous opioids which contribute to the development of OUD. Finally, we describe the intricate relationship between pain, endogenous opioid systems, and the proclivity for opioid misuse, as well as potential advances in generating safer and more efficient pain therapies.

Buprenorphine/naloxone versus methadone opioid rotation in patients with prescription opioid use disorder and chronic pain: study protocol for a randomized controlled trial

BACKGROUND

Opioids are effective in pain-management, but long-term opioid users can develop prescription opioid use disorder (OUD). One treatment strategy in patients with OUD is rotating from a short-acting opioid to a long-acting opioid (buprenorphine/naloxone (BuNa) or methadone). Both BuNa and methadone have been shown to be effective strategies in patients with OUD reducing opioid misuse, however data on head-to-head comparison in patients with chronic non-malignant pain and prescription OUD are limited.

METHODS

This two-armed open-label, randomized controlled trial aims to compare effectiveness between BuNa and methadone in patients with chronic non-malignant with prescription OUD (n = 100). Participants receive inpatient rotation to either BuNa or methadone with a flexible dosing regimen. The primary outcome is opioid misuse 2 months after rotation. Secondary outcomes include treatment compliance, side effects, analgesia, opioid craving, quality of life, mood symptoms, cognitive and physical functioning over 2- and 6 months follow-up. Linear mixed model analysis will be used to evaluate change in outcome parameters over time between the treatment arms.

DISCUSSION

This is one of the first studies comparing buprenorphine/naloxone and methadone for treating prescription OUD in a broad patient group with chronic non-malignant pain. Results may guide future treatment for patients with chronic pain and prescription OUD. Trial registration https://www.trialregister.nl/ , NL9781.

The Opioid System in Depression

Opioid receptors are widely distributed throughout the brain and play an essential role in modulating aspects of human mood, reward, and well-being. Accumulating evidence indicates the endogenous opioid system is dysregulated in depression and that pharmacological modulators of mu, delta, and kappa opioid receptors hold potential for the treatment of depression. Here we review animal and clinical data, highlighting evidence to support: dysregulation of the opioid system in depression, evidence for opioidergic modulation of behavioural processes and brain regions associated with depression, and evidence for opioidergic modulation in antidepressant responses. We evaluate clinical trials that have examined the safety and efficacy of opioidergic agents in depression and consider how the opioid system may be involved in the effects of other treatments, including ketamine, that are currently understood to exert antidepressant effects through non-opioidergic actions. Finally, we explore key neurochemical and molecular mechanisms underlying the potential therapeutic effects of opioid system engagement, that together provides a rationale for further investigation into this relevant target in the treatment of depression.

Mediation of the behavioral effects of ketamine and (2R,6R)-hydroxynorketamine in mice by kappa opioid receptors

Emerging evidence has implicated the endogenous opioid system in mediating ketamine's antidepressant activity in subjects with major depressive disorder. To date, mu opioid receptors have been suggested as the primary opioid receptor of interest. However, this hypothesis relies primarily on observations that the opioid antagonist naltrexone blocked the effects of ketamine in humans and rodents. This report confirms previous findings that pretreatment with naltrexone (1 mg/kg) just prior to ketamine (10 mg/kg) administration effectively blocks the behavioral effect of ketamine in the mouse forced swim test 24 h post-treatment. Furthermore, pharmacological blockade of kappa opioid receptors prior to ketamine administration with the selective, short-acting antagonist LY2444296 successfully blocked ketamine's effects in the forced swim test. Likewise, the ability of the ketamine metabolite (2R,6R)-hydroxynorketamine to reduce immobility scores in the forced swim test was also blocked following pretreatment with either naltrexone or LY2444296. These data support a potential role of kappa opioid receptors in mediating the behavioral activity of ketamine and its non-dissociate metabolite (2R,6R)-hydroxynorketamine.

Sex specific effects of buprenorphine on behavior, astrocytic opioid receptor expression and neuroinflammation after pediatric traumatic brain injury in mice

Children who suffered traumatic brain injury (TBI) often experience acute and chronic pain, which is linked to a poor quality of life. Buprenorphine (BPN) is commonly used to treat moderate to severe persistent pain in children, however, the efficacy and safety profile of BPN in the pediatric population is still inconclusive. This study investigated the sex-specific effects of BPN on body weight, motor coordination and strength, expression of opioid receptors in the white matter astrocytes, and neuroinflammation in a mouse impact acceleration model of pediatric TBI. Male and female littermates were randomized on postnatal day 20-21(P20-21) into Sham, TBI + saline and TBI + BPN groups. Mice in the TBI + saline and TBI + BPN groups underwent TBI, while the Sham group underwent anesthesia without injury. BPN (0.075 mg/kg) was administered to the TBI + BPN mice at 30 min after injury, and then every 6-12 h for 2 days. Mice in the TBI + saline group received the same amount of saline injections. The impact of BPN on body weight, motor function, opioid receptor expression, and neuroinflammation was evaluated at 1-day (d), 3-d and 7-d post-injury. We found that 1) TBI induced significant weight loss in both males and females. BPN treatment improved weight loss at 3-d post-injury in females. 2) TBI significantly impaired motor coordination and strength. BPN improved motor coordination and strength in both males and females at 1-d and 3-d post-injury. 3) TBI significantly decreased exploration activity at 1-d post-injury in males, and at 7-d post-injury in females, while BPN improved the exploration activity in females. 4) TBI significantly increased mRNA expression of mu-opioid receptors (MOR) at 7-d post-injury in males, but decreased mRNA expression of MOR at 1-d post-injury in females. BPN normalized MOR mRNA expression at 1-d post-injury in females. 5) MOR expression in astrocytes at corpus callosum significantly increased at 7-d post-injury in male TBI group, but significantly decreased at 1-d post-injury in female TBI group. BPN normalized MOR expression in both males and females. 6) TBI significantly increased the mRNA expression of TNF-α, IL-1β, IL-6 and iNOS. BPN decreased mRNA expression of iNOS, and increased mRNA expression of TGF-β1. In conclusion, this study elucidates the sex specific effects of BPN during the acute phase after pediatric TBI, which provides the rationale to assess potential effects of BPN on chronic pathological progressions after pediatric TBI in both males and females.

Anxiety treatment of methamphetamine-dependent patients with buprenorphine: A randomized, double-blind, clinical trial

Objectives

In this double-blind, randomized clinical trial, the effectiveness of buprenorphine (BUPRE) in the reduction of anxiety symptoms among the methamphetamine (MA) dependents was evaluated.

Materials and Methods

The 60 MA-dependent patients were randomly assigned to three groups (0.1 mg, 1 mg, and 8 mg of BUPRE), The Hamilton Anxiety Rating Scale was administrated to assess the anxiety symptoms daily at baseline and second to the 5^th day after intervention. The inclusion criteria were the MA dependence, age of over 18 years, and absence of any chronic physical illnesses; exclusion criteria were the presence of other drug dependence in combination with MA. The mixed-design analysis of variance was performed for data analysis.

Results

A significant main effect of time (F = 51.456, P < 0.001) and group (F = 4.572, P = 0.014) and group-by-time interaction (F = 8.475, P < 0.001) were detected.

Conclusions

This finding supports the efficacy of BUPRE to decrease anxiety. High doses of the drug (1 and 8 mg) were more effective than 0.1 mg. Here was not a significant difference between anxiety score when patients received 1 mg of BUPRE instead of 8 mg.

Patients on Buprenorphine Formulations Undergoing Surgery

PURPOSE OF REVIEW

To review the pharmacology of buprenorphine, the evolution of buprenorphine dosing recommendations, and the current literature regarding its recommendations for the perioperative period.

RECENT FINDINGS

There is a consensus that for all surgeries, buprenorphine should be continued throughout the perioperative period. If the surgery is a minimal to mild pain surgery, no dose adjustment is needed. There is no clear consensus regarding moderate to severe pain. With all surgeries, multimodal analgesia should be utilized, with regional anesthesia when possible. Patients taking buprenorphine should continue their buprenorphine perioperatively; whether to decrease or maintain dosing is up for debate. Multimodal analgesia should also be used throughout the perioperative period, and communication between the patient and all provider teams is of the utmost importance to provide adequate analgesia during the perioperative period, as well as to arrange safe analgesia upon discharge.

Association of PDYN 68-bp VNTR polymorphism with sublingual buprenorphine/naloxone treatment and with opioid or alcohol use disorder: Effect on craving, depression, anxiety and age onset of first use

In this case-control study (423 Turkish subjects), the functional pro-dynorphin (PDYN) 68-bp VNTR polymorphism was genotyped in opioid users receiving sublingual buprenorphine/naloxone treatment (SBNT; n = 129, 119 males and 10 females), in opioid users (OUD; n = 99, 90 males and 9 females), in alcohol users (AUD; n = 75, 75 males) and in controls (n = 120, 109 males and 11 females) to determine the effect of this polymorphism on different treatment responses, heroin or alcohol dependence as well as age onset of first use. The PDYN 68-bp alleles were determined based on the number of repeats and genotypes were classified as "short/short (SS)", "short-long (SL)" and "long-long (LL)". The intensity of craving, withdrawal, depression and anxiety were measured by the Substance Craving Scale (SCS), the Clinical Opiate Withdrawal Scale (COWS), the Beck Depression Inventory-II (BDI-II) and Beck Anxiety Inventory (BAI), respectively. Healthy controls (5.5 ± 5.8) had significantly lower levels of depressive symptoms compared to OUD (25.4 ± 13.5), AUD (22.5 ± 11.3) and SBNT (19.29 ± 12.2) groups. In OUD group, the LL genotype was associated with decreased intensity of anxiety and depressive symptoms than the SS+SL genotype. The BDI-II scores for PDYN VNTR genotypes within the 4 groups were analysed by two-way ANOVA and statistical differences were found for the groups. SBNT group had significantly lower COWS score than OUD group (1.00 versus 3.00). There were statistically significant differences in the median BAI (11 versus 24) and BDI-II scores (17.5 versus 25) between OUD and SBNT groups, supporting the antidepressant and anxiolytic effects of SBNT in persons with OUD.

Ketamine as a therapeutic agent for depression and pain: mechanisms and evidence

Ketamine is an anesthetic drug which is now used to treat chronic pain conditions and psychiatric disorders, especially depression. It is an N-methyl-D-aspartate (NMDA) receptor antagonist with additional effects on α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, opioid receptors, and monoaminergic receptors. This article focuses on ketamine's role in treating depression and pain, two commonly comorbid challenging conditions with potentially shared neurobiologic circuitry. Many clinical trials have utilized intravenous or intranasal ketamine for treating depression and pain. Intravenous ketamine is more bioavailable than intranasal ketamine and both are effective for acute depressive episodes. Intravenous ketamine is advantageous for post-operative analgesia and is associated with a reduction in total opioid requirements. Few studies have treated chronic pain or concurrent depression and pain with ketamine. Larger, randomized control trials are needed to examine the safety and efficacy of intravenous vs. intranasal ketamine, ideal target populations, and optimal dosing to treat both depression and pain.

Buprenorphine as a Treatment for Major Depression and Opioid Use Disorder

Rates of major depressive disorder (MDD) are disproportionally high in subjects with opioid use disorder (OUD) relative to the general population. MDD is often more severe in OUD patients, leading to compliance issues with maintenance therapies and poor outcomes. A growing body of literature suggests that endogenous opioid system dysregulation may play a role in the emergence of MDD. Buprenorphine, a mixed opioid receptor agonist/antagonist approved for the treatment of OUD and chronic pain, may have potential as a novel therapeutic for MDD, especially for patients with a dual diagnosis of MDD and OUD. This paper presents a comprehensive review of papers relevant to the assessment of buprenorphine as a treatment for MDD, OUD, and/or suicide compiled using electronic databases per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The principal goal of this literature review was to compile the clinical studies that have interrogated the antidepressant activity of buprenorphine in opioid naïve MDD patients and OUD patients with comorbid MDD. Evidence supporting buprenorphine's superiority over methadone for treating comorbid OUD and MDD was also considered. Finally, recent evidence for the ability of buprenorphine to alleviate suicidal ideation in both opioid-naïve patients and opioid-experienced patients was evaluated. Synthesizing all of this information, buprenorphine emerges as a potentially effective therapeutic for the dual purposes of treating MDD and OUD.

Novel Pharmacological Approaches to the Treatment of Depression

Major depressive disorder is one of the most prevalent mental health disorders. Monoamine-based antidepressants were the first drugs developed to treat major depressive disorder. More recently, ketamine and other analogues were introduced as fast-acting antidepressants. Unfortunately, currently available therapeutics are inadequate; lack of efficacy, adverse effects, and risks leave patients with limited treatment options. Efforts are now focused on understanding the etiology of depression and identifying novel targets for pharmacological treatment. In this review, we discuss promising novel pharmacological targets for the treatment of major depressive disorder. Targeting receptors including N-methyl-D-aspartate receptors, peroxisome proliferator-activated receptors, G-protein-coupled receptor 39, metabotropic glutamate receptors, galanin and opioid receptors has potential antidepressant effects. Compounds targeting biological processes: inflammation, the hypothalamic-pituitary-adrenal axis, the cholesterol biosynthesis pathway, and gut microbiota have also shown therapeutic potential. Additionally, natural products including plants, herbs, and fatty acids improved depressive symptoms and behaviors. In this review, a brief history of clinically available antidepressants will be provided, with a primary focus on novel pharmaceutical approaches with promising antidepressant effects in preclinical and clinical studies.

Neurocircuitry basis of the opioid use disorder-post-traumatic stress disorder comorbid state: conceptual analyses using a dimensional framework

Understanding the interface between opioid use disorder (OUD) and post-traumatic stress disorder (PTSD) is challenging. By use of a dimensional framework, such as research domain criteria, convergent and targetable neurobiological processes in OUD-PTSD comorbidity can be identified. We hypothesise that, in OUD-PTSD, circuitry that is implicated in two research domain criteria systems (ie, negative valence and cognitive control) underpins dysregulation of incentive salience, negative emotionality, and executive function. We also propose that the OUD-PTSD state might be systematically investigated with approaches outlined within a neuroclinical assessment framework for addictions and PTSD. Our dimensional analysis of the OUD-PTSD state shows how first-line therapeutic approaches (ie, partial μ-type opioid receptor [MOR1] agonism) modulate overlapping neurobiological and clinical features and also provides mechanistic rationale for evaluating polytherapeutic strategies (ie, partial MOR1 agonism, κ-type opioid receptor [KOR1] antagonism, and α-2A adrenergic receptor [ADRA2A] agonism). A combination of these therapeutic mechanisms is projected to facilitate recovery in patients with OUD-PTSD by mitigating negative valence states and enhancing executive control.

Problematic Opioid Use Among Older Adults: Epidemiology, Adverse Outcomes and Treatment Considerations

With the aging population, an increasing number of older adults (> 65 years) will be affected by problematic opioid use and opioid use disorder (OUD), with both illicit and prescription opioids. Problematic opioid use is defined as the use of opioids resulting in social, medical or psychological consequences, whereas OUD is a form of problematic use that meets diagnostic criteria as defined by the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition. Problematic use of opioids by older adults is associated with a number of pertinent adverse effects, including sedation, cognitive impairment, falls, fractures and constipation. Risk factors for problematic opioid use in this population include pain, comorbid medical illnesses, concurrent alcohol use disorder and depression. Treatment of OUD consists of acute detoxification and maintenance therapy. At this time, there have been no randomized controlled trials examining the effectiveness of pharmacological interventions for OUD in this population, with recommendations based on data from younger adults. Despite this, opioid agonist therapy (OAT) is recommended for both stages of treatment in older adults with OUD. Buprenorphine is recommended as a first line agent over methadone in the older adult population, due to a more favourable safety profile and relative accessibility. Use of methadone in this population is complicated by risk of QT interval prolongation and respiratory depression. Available observational data suggests that older adults respond well to OAT and age should not be a barrier to treatment. Further research is required to inform treatment decisions in this population.

'Not at all what I had expected': Discontinuing treatment with extended-release naltrexone (XR-NTX): A qualitative study

BACKGROUND

Extended-release naltrexone (XR-NTX), an opioid antagonist, has demonstrated equal treatment outcomes, in terms of safety, opioid use, and retention, to the recommended OMT medication buprenorphine. However, premature discontinuation of XR-NTX treatment is still common and poorly understood. Research on patient experiences of XR-NTX treatment is limited. We sought to explore participants' experiences with discontinuation of treatment with XR-NTX, particularly motivation for XR-NTX, experiences of initiation and treatment, and rationale for leaving treatment.

METHODS

We conducted qualitative, semi-structured interviews with participants from a clinical trial of XR-NTX. The study participants (N = 13) included seven women and six men with opioid dependence, who had received a minimum of one and maximum of four injections of XR-NTX. The study team analyzed transcribed interviews, employing thematic analysis with a critical realist approach.

FINDINGS

The research team identified three themes, and we present them as a chronological narrative: theme 1: Entering treatment - I thought I knew what I was going into; theme 2: Life with XR-NTX - I had something in me that I didn't want; and theme 3: Leaving treatment - I want to go somewhere in life. Patients' unfulfilled expectations of how XR-NTX would lead to a better life were central to decisions about discontinuation, including unexpected physical, emotional, or mental reactions as well as a lack of expected effects, notably some described an opioid effect from buprenorphine. A few participants ended treatment because they had reached their treatment goal, but most expressed disappointment about not achieving this goal. Some also expressed renewed acceptance of OMT. The participants' motivation for abstinence from illegal substances generally remained.

CONCLUSION

Our findings emphasize that a dynamic understanding of discontinuation of treatment is necessary to achieve a long-term approach to recovery: the field should understand discontinuation as a feature of typical treatment trajectories, and discontinuation can be followed by re-initiation of treatment.

Novel drug developmental strategies for treatment-resistant depression

Major depressive disorder is a leading cause of disability worldwide. Because conventional therapies are ineffective in many patients, novel strategies are needed to overcome treatment‐resistant depression (TRD). Limiting factors of successful drug development in the last decades were the lack of (1) knowledge of pathophysiology, (2) translational animal models and (3) objective diagnostic biomarkers. Here, we review novel drug targets and drug candidates currently investigated in Phase I–III clinical trials. The most promising approaches are inhibition of glutamatergic neurotransmission by NMDA and mGlu₅ receptor antagonists, modulation of the opioidergic system by κ receptor antagonists, and hallucinogenic tryptamine derivates. The only registered drug for TRD is the NMDA receptor antagonist, S‐ketamine, but add‐on therapies with second‐generation antipsychotics, certain nutritive, anti‐inflammatory and neuroprotective agents seem to be effective. Currently, there is an intense research focus on large‐scale, high‐throughput omics and neuroimaging studies. These results might provide new insights into molecular mechanisms and potential novel therapeutic strategies.

Illicit Drug Use in Older Adults: An Invisible Epidemic?

Illicit drug use/misuse among older adults is understudied, although current trends point to older adults being the fastest-growing segment in the United States and other developed countries. There is a need for further insight into drug use patterns in older adults, who face their own set of socioeconomic, medical, and psychiatric problems. We reviewed the literature for data related to use/misuse of heroin and stimulants (cocaine, amphetamines, and methamphetamines) among people over the age of 40 years. We focused on prevalence rates of use/misuse of these substances, comorbidities, diagnostic challenges, screening tools, and treatment recommendations specific to the geriatric population.

Antipanic-like effect of esketamine and buprenorphine in rats exposed to acute hypoxia

The antidepressant effect of ketamine has been widely acknowledged and the use of one of its enantiomers, S-ketamine (esketamine), has recently been approved for the clinical management of treatment-resistant depression. As with ketamine, the non-selective opioid receptor-interacting drug buprenorphine is reported to have antidepressant and anxiolytic properties in humans and rodents. Given the fact that antidepressant drugs are also first line treatment for panic disorder, it is surprising that the potential panicolytic effect of these compounds has been scarcely (ketamine), or not yet (buprenorphine) investigated. We here evaluated the effects of ketamine (the racemic mixture), esketamine, and buprenorphine in male Wistar rats submitted to a panicogenic challenge: acute exposure to hypoxia (7% O₂). We observed that esketamine (20 mg/kg), but not ketamine, decreased the number of escape attempts made during hypoxia, and this effect could be observed even 7 days after the drug administration. A panicolytic-like effect was also observed with MK801, which like esketamine, antagonizes NMDA glutamate receptors. Buprenorphine (0.3 mg/kg) also impaired hypoxia-induced escape, an effect blocked by the non-selective opioid receptor antagonist naloxone, indicating an interaction with classical ligand sites, such as µ and kappa receptors, but not with nociception/orphanin FQ receptors. Altogether, the results suggest that esketamine and buprenorphine cause rapid-onset panicolytic-like effects, and may be alternatives for treating panic disorder, particularly in patients who are refractory to standard pharmacological treatment.

Low-Dose Augmentation With Buprenorphine for Treatment-Resistant Depression: A Multisite Randomized Controlled Trial With Multimodal Assessment of Target Engagement

Background

The experimental therapeutics approach that combines a placebo-controlled clinical trial with translational neuroscience methods can provide a better understanding of both the clinical and physiological effects of pharmacotherapy. We aimed to test the efficacy and tolerability of low-dose augmentation with buprenorphine (BPN) for treatment-resistant depression, combined with multimodal assessment of target engagement.

Methods

In this multisite randomized clinical trial, 85 participants ≥50 years of age with a major depressive episode that had not responded to venlafaxine extended release were randomized to augmentation with BPN or placebo for 8 weeks. The primary outcome measure was the Montgomery-Åsberg Depression Rating Scale. In addition, three linked experiments were conducted to test target engagement: 1) functional magnetic resonance imaging using the monetary incentive delay task, 2) brain positron emission tomography of healthy participants using a novel kappa opioid receptor antagonist tracer [¹¹C]LY2795050, and 3) transcranial magnetic stimulation measure of cortical transmission after daily BPN administration.

Results

The mean ± SD dosage of BPN was 0.59 ± 0.33 mg/day. There were no significant differences between the BPN and placebo groups in Montgomery-Åsberg Depression Rating Scale changes over time or adverse effects. BPN administration had minimal effects on functional magnetic resonance imaging blood oxygen level-dependent responses in regions involved in reward anticipation and response, no significant displacement of kappa opioid receptor radioligand in positron emission tomography imaging, and no significant changes in transcranial magnetic stimulation measures of inhibitory and excitatory cortical transmission.

Conclusions

Our findings suggest a lack of clinical effect of low-dose BPN augmentation and lack of target engagement with this dosage and physiological probes.

Characterizing anhedonia: A systematic review of neuroimaging across the subtypes of reward processing deficits in depression

Anhedonia is a key symptom of major depressive disorder (MDD) and comprises behavioural deficits in three reward processing subtypes: reward liking, reward wanting, and reward learning. However, neuroimaging findings regarding the neural abnormalities underpinning these deficits are complex. We have conducted a systematic review to update, reframe and summarize neuroimaging findings across the three subtypes of anhedonia in MDD. Using PubMed, The Cochrane Library, PsycINFO, and Web of Science databases, we identified 59 fMRI studies comparing participants with current or remitted MDD with controls, using reward processing tasks. For reward liking and wanting, striatal hypoactivation was observed, alongside hypoactivation and hyperactivation across frontal regions. For reward learning, blunted frontostriatal sensitivity to positive feedback was observed. These findings highlight the importance of studying anhedonia not only as a clinical manifestation but also as a neurobiological mechanism underlying depressive disorder and other broader psychiatric conditions.

Beneficial Effects of Opioid Rotation to Buprenorphine/Naloxone on Opioid Misuse, Craving, Mental Health, and Pain Control in Chronic Non-Cancer Pain Patients with Opioid Use Disorder

Patients with chronic non-cancer pain (CNCP) often use opioids for long periods of time. This may lead to opioid use disorder (OUD) and psychiatric symptoms: mainly depression and anxiety. The current study investigated the effect of buprenorphine/naloxone (BuNa) rotation on opioid misuse, craving, psychiatric symptoms and pain in patients with CNCP and OUD. Forty-three participants with CNCP and OUD were converted from a full mu-receptor agonist opioid (mean morphine equivalent dose: 328.3 mg) to BuNa, in an inpatient setting. Opioid misuse, craving, co-occurring psychiatric symptoms, and pain perception were determined at baseline and after a two-month follow-up, using the following self-report questionnaires: Current Opioid Misuse Measurement (COMM), Visual Analog Scale (VAS-craving and VAS-pain) and Depression, Anxiety and Stress Scale (DASS), respectively. VAS-craving and VAS-pain were also determined immediately after conversion. A total of 37 participants completed the protocol. The mean COMM decreased from 17.1 to 6.7 (F = 36.5; p < 0.000), the mean VAS-craving decreased from 39.3 to 5.3 (−86.6%; F = 26.5, p < 0.000), the mean DASS decreased from 12.1 to 6.6 (F = 56.3, p < 0.000), and the mean VAS-pain decreased from 51.3 to 37.2 (−27.4%, F = 3.3; p = 0.043). Rotation to BuNa in patients with CNCP and OUD was accompanied by reductions in (i) opioid misuse, (ii) opioid craving, (iii) the severity of co-occurring psychiatric symptoms, and (iv) self-reported pain. BuNa as opioid agonist treatment may therefore be a beneficial strategy in CNCP patients with OUD. The limited sample size and the observational nature of this study underline the need for the replication of the current findings in large-scale, controlled studies.

Mechanisms Underlying the Anti-Suicidal Treatment Potential of Buprenorphine

Death by suicide is a global epidemic with over 800 K suicidal deaths worlwide in 2012. Suicide is the 10th leading cause of death among Americans and more than 44 K people died by suicide in 2019 in the United States. Patients with chronic pain, including, but not limited to, those with substance use disorders, are particularly vulnerable. Chronic pain patients have twice the risk of death by suicide compared to those without pain, and 50% of chronic pain patients report that they have considered suicide at some point due to their pain. The kappa opioid system is implicated in negative mood states including dysphoria, depression, and anxiety, and recent evidence shows that chronic pain increases the function of this system in limbic brain regions important for affect and motivation. Additionally, dynorphin, the endogenous ligand that activates the kappa opioid receptor is increased in the caudate putamen of human suicide victims. A potential treatment for reducing suicidal ideation and suicidal attempts is buprenorphine. Buprenorphine, a partial mu opioid agonist with kappa opioid antagonist properties, reduced suicidal ideation in chronic pain patients with and without an opioid use disorder. This review will highlight the clinical and preclinical evidence to support the use of buprenorphine in mitigating pain-induced negative affective states and suicidal thoughts, where these effects are at least partially mediated via its kappa antagonist properties.

Explaining differential effects of medication for opioid use disorder using a novel approach incorporating mediating variables

BACKGROUND AND AIMS

A recent study found that homeless individuals with opioid use disorder (OUD) had a lower risk of relapse on extended-release naltrexone (XR-NTX) versus buprenorphine-naloxone (BUP-NX), whereas non-homeless individuals had a lower risk of relapse on BUP-NX. This secondary study examined differences in mediation pathways to medication effect between homeless and non-homeless participants.

DESIGN

Secondary analysis of an open-label randomized controlled, 24-week comparative effectiveness trial, 2014-17.

SETTING

Eight community addiction treatment programs in the United States.

PARTICIPANTS

English-speaking adults with DSM-5 OUD, recruited during inpatient admission (n = 570).

INTERVENTION(S)

Randomization to monthly injection of XR-NTX or daily sublingual BUP-NX.

MEASUREMENTS(S)

Mediation analysis estimated the direct effect of XR-NTX versus BUP-NX on relapse and indirect effect through mediators of medication adherence, use of illicit opioids, depressive symptoms and pain, separately by homeless status.

FINDINGS

For the homeless subgroup, the protective indirect path contributed a 3.4 percentage point reduced risk of relapse [95% confidence interval (CI) = -12.0, 5.3] comparing XR-NTX to BUP-NX (explaining 21% of the total effect). For the non-homeless subgroup, the indirect path contributed a 9.4 percentage point increased risk of relapse (95% CI = 3.1, 15.7) comparing XR-NTX to BUP-NX (explaining 57% of the total effect).

CONCLUSIONS

A novel approach to mediation analysis shows that much of the difference in medication effectiveness (extended-release naltrexone versus buprenorphine-naloxone) on opioid relapse among non-homeless adults with opioid use disorder appears to be explained by mediators of adherence, illicit opioid use, depressive symptoms and pain.

Can pharmacotherapy improve treatment outcomes in people with co-occurring major depressive and cocaine use disorders?

Introduction: Major depressive disorder (MDD) and cocaine use disorder (CUD) are prevalent and frequently co-occur. When co-occurring, the presence of one disorder typically negatively impacts the prognosis for the other. Given the clinical relevance, we sought to examine pharmacotherapies for co-occurring CUD and MDD. While multiple treatment options have been examined in the treatment of each condition individually, studies exploring pharmacological options for their comorbidity are fewer and not conclusive.Areas Covered: For this review, the authors searched the literature in PubMed using clinical query options for therapies and keywords relating to each condition. Then, they described potentially promising pharmacologic therapeutic options based on shared mechanisms between the two conditions and/or results from individual clinical trials conducted to date.Expert opinion: Medications like stimulants, dopamine (D3) receptors partial agonists or antagonists, antagonists of kappa opioid receptors, topiramate, and ketamine could be promising as there is significant overlap relating to reward deficiency models, antireward pathways, and altered glutamatergic systems. However, the available clinical literature on any one of these types of agents is mixed. Additionally, for some agents there is possible concern related to abuse potential (e.g. ketamine and stimulants).

Novel Targets to Treat Depression: Opioid-Based Therapeutics

After participating in this activity, learners should be better able to:• Identify the effects of dysregulated opioid signalling in depression• Evaluate the use of opioid compounds and ketamine in patients with depression ABSTRACT: Major depressive disorder (MDD) remains one of the leading causes of disability and functional impairment worldwide. Current antidepressant therapeutics require weeks to months of treatment prior to the onset of clinical efficacy on depressed mood but remain ineffective in treating suicidal ideation and cognitive impairment. Moreover, 30%-40% of individuals fail to respond to currently available antidepressant medications. MDD is a heterogeneous disorder with an unknown etiology; novel strategies must be developed to treat MDD more effectively. Emerging evidence suggests that targeting one or more of the four opioid receptors-mu (MOR), kappa (KOR), delta (DOR), and the nociceptin/orphanin FQ receptor (NOP)-may yield effective therapeutics for stress-related psychiatric disorders. Furthermore, the effects of the rapidly acting antidepressant ketamine may involve opioid receptors. This review highlights dysregulated opioid signaling in depression, evaluates clinical trials with opioid compounds, and considers the role of opioid mechanisms in rapidly acting antidepressants.

The administration of the opioid buprenorphine decreases motivational error signals

While opioid addiction has reached pandemic proportions, we still lack a good understanding of how the administration of opioids interacts with cognitive functions. Error processing - the ability to detect erroneous actions and correct one's behaviour afterwards - is one such cognitive function that might be susceptible to opioidergic influences. Errors are hypothesised to induce aversive negative arousal, while opioids have been suggested to reduce aversive arousal induced by unpleasant and stressful stimuli. Thus, this study investigated whether the acute administration of an opioid would affect error processing. In a double-blind between-subject study, 42 male volunteers were recruited and received either 0.2 mg buprenorphine (a partial µ-opioid receptor agonist and κ-opioid receptor antagonist) or a placebo pill before they performed a stimulus-response task provoking errors. Electroencephalograms (EEG) were recorded while participants performed the task. We observed no group differences in terms of reaction times, error rates, and affective state ratings during the task between buprenorphine and control participants. Additional measures of adaptive control, however, showed interfering effects of buprenorphine administration. On the neural level, decreased Pe (Error Positivity) amplitudes were found in buprenorphine compared to control participants following error commission. Further, frontal delta oscillations were decreased in the buprenorphine group after all responses. Our neural results jointly demonstrate a general reduction in error processing in those participants who received an opioid before task completion, thereby suggesting that opioids might have indeed the potential to dampen motivational error signals. Importantly, the effects of the opioid were evident in more elaborate error processing stages, thereby impacting on processes of conscious error appraisal and evidence accumulation.

Benefit-Risk Analysis of Buprenorphine for Pain Management

Health care providers in the United States are facing challenges in selecting appropriate medication for patients with acute and chronic pain in the midst of the current opioid crisis and COVID-19 pandemic. When compared with conventional opioids, the partial µ-opioid receptor agonist buprenorphine has unique pharmacologic properties that may be more desirable for pain management. The formulations of buprenorphine approved by the US Food and Drug Administration for pain management include intravenous injection, transdermal patch, and buccal film. A comparison of efficacy and safety data from studies of buprenorphine and conventional opioids suggests that buprenorphine may be a better-tolerated treatment option for many patients that provides similar or superior analgesia. Our benefit-risk assessment in this narrative review suggests that health care providers should consider that buprenorphine may be an appropriate alternative for pain management over other opioids.

Opioid use during pregnancy can impair maternal behavior and the Maternal Brain Network: A literature review

Opioid Use Disorder (OUD) is a global epidemic also affecting women of reproductive age. A standard form of pharmacological treatment for OUD is Opioid Maintenance Therapy (OMT) and buprenorphine has emerged as the preferred treatment for pregnant women with OUD relative to methadone. However, the consequences of BUP exposure on the developing Maternal Brain Network and mother-infant dyad are not well understood. The maternal-infant bond is dependent on the Maternal Brain Network, which is responsible for the dynamic transition from a "nulliparous brain" to a "maternal brain". The Maternal Brain Network consists of regions implicated in maternal care (e.g., medial preoptic area, nucleus accumbens, ventral pallidum, ventral tegmentum area) and maternal defense (e.g., periaqueductal gray). The endogenous opioid system modulates many of the neurochemical changes in these areas during the transition to motherhood. Thus, it is not surprising that exogenous opioid exposure during pregnancy can be disruptive to the Maternal Brain Network. Though less drastic than misused opioids, OMTs may not be without risk of disrupting the neural and molecular structures of the Maternal Brain Network. This review describes the Maternal Brain Network as a framework for understanding how pharmacological differences in exogenous opioid exposure can disrupt the onset and maintenance of the maternal brain and summarizes opioid and OMT (in particular buprenorphine) use in the context of pregnancy and maternal behavior. This review also highlights future directions for evaluating exogenous opioid effects on the Maternal Brain Network in the hopes of raising awareness for the impact of the opioid crisis not only on exposed infants, but also on mothers and subsequent mother-infant bonds.