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Although opioids have known antidepressant activity, their use in major depressive disorder (MDD) has been greatly limited by risk of abuse and addiction. Our aim was to determine whether opioid modulation achieved through a combination of a μ-opioid partial agonist, buprenorphine (BUP), and a potent μ-opioid antagonist, samidorphan (SAM), would demonstrate antidepressant activity without addictive potential. A placebo-controlled crossover study assessed the opioid pharmacodynamic profile following escalating doses of SAM co-administered with BUP in opioid-experienced adults. A subsequent 1-week, placebo-controlled, parallel-group study was conducted in subjects with MDD and an inadequate response to standard antidepressant therapy. This second study evaluated safety and efficacy of ratios of BUP/SAM that were associated with partial and with maximal blockade of opioid responses in the initial study. Pupillometry, visual analog scale assessments, and self-reported questionnaires demonstrated that increasing amounts of SAM added to a fixed dose of BUP resulted in dose-dependent reductions in objective and subjective opioid effects, including euphoria and drug liking, in opioid-experienced adults. Following 7 days of treatment in subjects with MDD, a 1 : 1 ratio of BUP and SAM, the ratio associated with maximal antagonism of opioid effects, exhibited statistically significant improvement vs placebo in HAM-D17 total score (p=0.032) and nearly significant improvement in Montgomery-Åsberg Depression Rating Scale (MADRS) total score (p=0.054). Overall, BUP/SAM therapy was well tolerated. A combination of BUP and SAM showed antidepressant activity in subjects with MDD. Balanced agonist-antagonist opioid modulation represents a novel and potentially clinically important approach to the treatment of MDD and other psychiatric disorders.

The endogenous opioid system is thought to play an important role in the regulation of mood. Buprenorphine/samidorphan (BUP/SAM) combination is an investigational opioid system modulator for adjunctive treatment of major depressive disorder (MDD). To confirm results from early studies, we report the efficacy and safety of BUP/SAM as adjunctive treatment in patients with MDD and an inadequate response to antidepressant therapy (ADT) in FORWARD-4 and FORWARD-5: two phase 3, randomized, double-blind, placebo-controlled studies that utilized the same sequential parallel-comparison design. Efficacy was measured using the Montgomery–Åsberg Depression Rating Scale (MADRS). FORWARD-5 achieved the primary endpoint and demonstrated that adjunctive BUP/SAM 2 mg/2 mg was superior to placebo (average difference change from baseline to week 3 through end of treatment [EOT] in MADRS-6 and −10 versus placebo: −1.5, P = 0.018; −1.9, P = 0.026, respectively). FORWARD-4 did not achieve the primary endpoint (change from baseline in MADRS-10 at week 5 versus placebo: –1.8, P = 0.109), although separate analyses showed significant treatment differences at other timepoints using traditional, regulatory-accepted endpoints such as reduction in MADRS-10 at EOT. The pooled analysis of the two studies demonstrated consistently greater reduction in MADRS-10 scores from baseline for BUP/SAM 2 mg/2 mg versus placebo at multiple timepoints including EOT and average change from baseline to week 3 through EOT (–1.8, P = 0.010; –1.8, P = 0.004, respectively). The overall effect size (Hedges’ g) in the pooled analyses for MADRS-10 change from baseline to EOT was 0.22. Overall, BUP/SAM was generally well tolerated, with most adverse events (AEs) being mild or moderate in severity. The most common AEs, occurring in ≥5% of patients in the BUP/SAM 2 mg/2 mg treatment group, which was more frequently than the placebo group, included nausea, constipation, dizziness, vomiting, somnolence, fatigue, and sedation. There was minimal evidence of abuse, and no evidence of dependence or opioid withdrawal by AEs or objective measures. This report describes adjunctive BUP/SAM 2 mg/2 mg combination, a therapy with a novel opioidergic mechanism of action, as a potential new treatment option for patients with MDD who have an inadequate response to currently available ADT.

This study investigated the safety and efficacy of subcutaneous methylnaltrexone, a μ-opioid–receptor antagonist, for treating opioid-induced constipation in patients with advanced illness. Methylnaltrexone rapidly induced laxation without affecting central analgesia or precipitating withdrawal. This study investigated the safety and efficacy of subcutaneous methylnaltrexone for treating opioid-induced constipation in patients with advanced illness. Methylnaltrexone rapidly induced laxation without affecting central analgesia or precipitating withdrawal. Clinicians often use opioids to treat moderate-to-severe pain; however, opioids frequently induce or aggravate constipation. Empirically, laxative therapy may be burdensome and ineffective and result in temporally unpredictable responses. In addition, severe opioid-induced constipation may limit opioid therapy, worsening analgesia. These drawbacks can substantially compromise the quality of life, especially in patients with advanced illness. Opioid-induced constipation is predominantly mediated by gastrointestinal μ-opioid receptors. 1 , 2 Selective blockade of these peripheral receptors might relieve constipation without compromising centrally mediated effects of opioid analgesia or precipitating withdrawal. N-methylation of the uncharged systemic opioid antagonist, naltrexone, 3 results in a charged derivative, methylnaltrexone, which . . .

INTRODUCTION:Opioids used to manage severe pain in acute pancreatitis (AP) might exacerbate the disease through effects on gastrointestinal and immune functions. Methylnaltrexone, a peripherally acting µ-opioid receptor antagonist, may counteract these effects without changing analgesia.METHODS:This double-blind, randomized, placebo-controlled trial included adult patients with AP and systemic inflammatory response syndrome at 4 Danish centers. Patients were randomized to receive 5 days of continuous intravenous methylnaltrexone (0.15 mg/kg/d) or placebo added to the standard of care. The primary end point was the Pancreatitis Activity Scoring System score after 48 hours of treatment. Main secondary outcomes included pain scores, opioid use, disease severity, and mortality.RESULTS:In total, 105 patients (54% men) were randomized to methylnaltrexone (n = 51) or placebo (n = 54). After 48 hours, the Pancreatitis Activity Scoring System score was 134.3 points in the methylnaltrexone group and 130.5 points in the placebo group (difference 3.8, 95% confidence interval [CI] −40.1 to 47.6; P = 0.87). At 48 hours, we found no differences between the groups in pain severity (0.0, 95% CI −0.8 to 0.9; P = 0.94), pain interference (−0.3, 95% CI −1.4 to 0.8; P = 0.55), and morphine equivalent doses (6.5 mg, 95% CI −2.1 to 15.2; P = 0.14). Methylnaltrexone also did not affect the risk of severe disease (8%, 95% CI −11 to 28; P = 0.38) and mortality (6%, 95% CI −1 to 12; P = 0.11). The medication was well tolerated.DISCUSSION:Methylnaltrexone treatment did not achieve superiority over placebo for reducing the severity of AP.

RationaleAlcohol use disorder is a common and devastating mental illness for which satisfactory treatments are still lacking. Nalmefene, as an opioid receptor modulator, could pharmacologically support the reduction of drinking by reducing the (anticipated) rewarding effects of alcohol and expanding the range of treatment options. It has been hypothesized that nalmefene acts via an indirect modulation of the mesolimbic reward system. So far, only a few imaging findings on the neuronal response to nalmefene are available.ObjectivesWe tested the effect of a single dose of 18 mg nalmefene on neuronal cue-reactivity in the ventral and dorsal striatum and subjective craving.MethodsEighteen non-treatment-seeking participants with alcohol use disorder (67% male, M = 50.3 ± 13.9 years) with a current high-risk drinking level (M = 76.9 ± 52 g of pure alcohol per day) were investigated using a cue-reactivity task during functional magnetic resonance imaging (fMRI) in a double-blind, placebo-controlled, cross-over study/design. In addition, self-reported craving was assessed before and after exposure to alcohol cues.ResultsAn a priori defined region of interest (ROI) analysis of fMRI data from 15 participants revealed that nalmefene reduced alcohol cue-reactivity in the ventral, but not the dorsal striatum. Additionally, the subjective craving was significantly reduced after the cue-reactivity task under nalmefene compared to placebo.ConclusionIn the present study, reduced craving and cue-reactivity to alcohol stimuli in the ventral striatum by nalmefene indicates a potential anti-craving effect of this drug via attenuation of neural alcohol cue-reactivity.

A combination of olanzapine and samidorphan (OLZ/SAM) received US Food and Drug Administration approval in May 2021 for the treatment of adults with schizophrenia or bipolar I disorder. OLZ/SAM provides the efficacy of olanzapine, while mitigating olanzapine-associated weight gain. This exploratory study characterized the metabolic profile of OLZ/SAM in healthy volunteers to gain mechanistic insights. Volunteers received once-daily oral 10 mg/10 mg OLZ/SAM, 10 mg olanzapine, or placebo for 21 days. Assessments included insulin sensitivity during an oral glucose tolerance test (OGTT), hyperinsulinemic-euglycemic clamp, other measures of glucose/lipid metabolism, and adverse event (AE) monitoring. Treatment effects were estimated with analysis of covariance. In total, 60 subjects were randomized (double-blind; placebo, n = 12; olanzapine, n = 24; OLZ/SAM, n = 24). Olanzapine resulted in hyperinsulinemia and reduced insulin sensitivity during an OGTT at day 19, changes not observed with OLZ/SAM or placebo. Insulin sensitivity, measured by hyperinsulinemic-euglycemic clamp, was decreased in all treatment groups relative to baseline, but this effect was greatest with olanzapine and OLZ/SAM. Although postprandial (OGTT) glucose and fasting cholesterol concentrations were similarly increased with olanzapine or OLZ/SAM, other early metabolic effects were distinct, including post-OGTT C-peptide concentrations and aspects of energy metabolism. Forty-nine subjects (81.7%) experienced at least 1 AE, most mild or moderate in severity. OLZ/SAM appeared to mitigate some of olanzapine’s unfavorable postprandial metabolic effects (e.g., hyperinsulinemia, elevated C-peptide) in this exploratory study. These findings supplement the body of evidence from completed or ongoing OLZ/SAM clinical trials supporting its role in the treatment of schizophrenia and bipolar I disorder.

Combination olanzapine and samidorphan (OLZ/SAM), in development for schizophrenia and bipolar I disorder, is intended to provide the efficacy of olanzapine while mitigating olanzapine-associated weight gain. OLZ/SAM safety, tolerability, and efficacy from a 52-week open-label extension study in patients with schizophrenia are reported. Patients previously completing the 4-week, double-blind ENLIGHTEN-1 study switched from OLZ/SAM, olanzapine, or placebo to OLZ/SAM. Assessments included adverse events (AEs), weight, vital signs, Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impression-Severity (CGI-S) scores. Baseline was prior to first dose of OLZ/SAM in the extension study. In total, 281 patients enrolled, 277 received ≥1 OLZ/SAM dose, and 183 (66.1%) completed 52 weeks. Reasons for discontinuation included patient withdrawal (15.5%), loss to follow-up (6.9%), AEs (5.8%), and lack of efficacy (1.8%). AEs were reported in 136 (49.1%) patients; increased weight (13%) and somnolence (8%) were most common. Ten serious AEs were reported in eight patients (2.9%); none were considered treatment related. There were no deaths. Mean (SD) baseline weight was 79.1 (17.8) kg. Mean weight change from baseline to week 52 was 1.86 kg (2.79% increase). PANSS total and CGI-S scores continued to decline over 52 weeks (mean [95% CI] changes from baseline to week 52: -16.2 [-18.5, -14.0] and -0.9 [-1.0, -0.8], respectively). OLZ/SAM was generally well tolerated in this extension study; most patients completed the 52-week treatment period with sustained improvement in schizophrenia symptoms. Mean increases in weight stabilized by week 6 with limited subsequent change through end of treatment.

Abstract Objective This study evaluated the efficacy and safety of oral naldemedine 0.1 mg, 0.2 mg, or 0.4 mg once daily in patients who had opioid-induced constipation (OIC) and maintained a stable laxative regimen. Methods This four-week, phase 2b, randomized, double-blind placebo-controlled trial (clinicaltrials.gov identifier NCT01443403) enrolled patients on long-term opioid therapy for chronic noncancer pain with OIC. The primary efficacy end point was change in weekly spontaneous bowel movement (SBM) frequency from baseline to the last two weeks of treatment. Secondary end points included the proportion of SBM responders (patients with ≥3 SBMs/week and an increase of ≥1 SBM/week from baseline over the last 2 weeks of treatment). Safety parameters assessed included adverse events, effects on analgesia, and opioid withdrawal symptoms. Results Overall, 244 patients were randomized 1:1:1:1 to naldemedine 0.1 mg, 0.2 mg, 0.4 mg, or placebo. Baseline patient characteristics were comparable. Weekly SBM frequency was significantly higher with naldemedine 0.2 mg (3.37, P = 0.0014) and 0.4 mg (3.64, P = 0.0003), but not with 0.1 mg (1.98, P = 0.3504), vs placebo (1.42). The proportion of SBM responders was significantly higher with naldemedine 0.2 mg (71.2%, P = 0.0005) and 0.4 mg (66.7%, P = 0.003), but not with 0.1 mg (52.5%, P = 0.1461), vs placebo (39.3%). Treatment-emergent adverse events were generally mild to moderate in severity; incidences increased with naldemedine dose. No clinically meaningful changes in other safety parameters were observed. Conclusion Naldemedine 0.2 mg once daily is the optimal dose for future confirmatory trials in OIC.

PurposeConstipation can be a significant problem in critically unwell patients, associated with detrimental outcomes. Opioids are thought to contribute to the mechanism of bowel dysfunction. We tested if methylnaltrexone, a pure peripheral mu-opioid receptor antagonist, could reverse opioid-induced constipation.MethodsThe MOTION trial is a multi-centre, double blind, randomised placebo-controlled trial to investigate whether methylnaltrexone alleviates opioid-induced constipation (OIC) in critical care patients. Eligibility criteria included adult ICU patients who were mechanically ventilated, receiving opioids and were constipated (had not opened bowels for a minimum 48 h) despite prior administration of regular laxatives as per local bowel management protocol. The primary outcome was time to significant rescue-free laxation. Secondary outcomes included gastric residual volume, tolerance of enteral feeds, requirement for rescue laxatives, requirement for prokinetics, average number of bowel movements per day, escalation of opioid dose due to antagonism/reversal of analgesia, incidence of ventilator-associated pneumonia, incidence of diarrhoea and Clostridium difficile infection and finally 28 day, ICU and hospital mortality.ResultsA total of 84 patients were enrolled and randomized (41 to methylnaltrexone and 43 to placebo). The baseline demographic characteristics of the two groups were generally well balanced. There was no significant difference in time to rescue-free laxation between the groups (Hazard ratio 1.42, 95% CI 0.82–2.46, p = 0.22). There were no significant differences in the majority of secondary outcomes, particularly days 1–3. However, during days 4–28, there were fewer median number of bowel movements per day in the methylnaltrexone group, (p = 0.01) and a greater incidence of diarrhoea in the placebo group (p = 0.02). There was a marked difference in mortality between the groups, with ten deaths in the methylnaltrexone group and two in the placebo group during days 4–28 (p = 0.007).ConclusionWe found no evidence to support the addition of methylnaltrexone to regular laxatives for the treatment of opioid-induced constipation in critically ill patients; however, the confidence interval was wide and a clinically important difference cannot be excluded.

A combination of olanzapine and the opioid receptor antagonist samidorphan (OLZ/SAM) has been approved in the United States for the treatment of adults with schizophrenia or adults with bipolar I disorder. In a phase 3 study in adults with schizophrenia (ENLIGHTEN-2), OLZ/SAM treatment was associated with significantly less weight gain compared with olanzapine. Prespecified subgroup analyses explored the consistency of the weight mitigation effect of OLZ/SAM vs olanzapine across demographic subgroups in ENLIGHTEN-2. The multicenter, randomized, double-blind ENLIGHTEN-2 study (NCT02694328) included outpatients aged 18-55 years with a diagnosis of schizophrenia based on DSM-5 criteria, a body mass index (BMI) of 18 to 30 kg/m , and stable body weight (self-reported change ≤5% for ≥3 months before study entry). Patients were randomized 1:1 to receive OLZ/SAM or olanzapine for 24 weeks. Co-primary endpoints (previously reported) were percent change in body weight and proportion of patients with at least 10% weight gain from baseline at week 24. Prespecified exploratory subgroup analyses by sex, age, self-reported race, and baseline BMI were conducted. At week 24, treatment with OLZ/SAM resulted in numerically less percent weight gain than with olanzapine across all subgroups evaluated. The proportion of patients with at least 10% weight gain was smaller in each subgroup treated with OLZ/SAM vs olanzapine. In these exploratory subgroup analyses from the ENLIGHTEN-2 study, weight-mitigating effects of OLZ/SAM vs olanzapine were observed consistently across patient subgroups and were in line with results from the overall study population.