Comparative efficacy of racemic ketamine and esketamine for depression: A systematic review and meta-analysis

Subcutaneous ketamine infusion in palliative patients for major depressive disorder (SKIPMDD)-Phase II single-arm open-label feasibility study

BACKGROUND

Ketamine at subanaesthetic dosages (≤0.5mg/kg) exhibits rapid onset (over hours to days) antidepressant effects against major depressive disorder in people who are otherwise well. However, its safety, tolerability and efficacy are not known for major depressive disorder in people with advanced life-limiting illnesses.

OBJECTIVE

To determine the feasibility, safety, tolerability, acceptability and any antidepressant signal/activity to justify and inform a fully powered study of subcutaneous ketamine infusions for major depressive disorder in the palliative setting.

METHODS

This was a single arm, open-label, phase II feasibility study (Australian New Zealand Clinical Trial Registry Number-ACTRN12618001586202). We recruited adults (≥ 18-years-old) with advanced life-limiting illnesses referred to four palliative care services in Sydney, Australia, diagnosed with major depressive disorder from any care setting. Participants received weekly subcutaneous ketamine infusion (0.1-0.4mg/kg) over two hours using individual dose-titration design. Outcomes assessed were feasibility, safety, tolerability and antidepressant activity.

RESULTS

Out of ninety-nine referrals, ten participants received ketamine and were analysed for responses. Accrual rate was 0.54 participants/month across sites with 50% of treated participants achieving ≥ 50% reduction in baseline Montgomery-Åsberg Depression Rating Scale, meeting feasibility criteria set a priori. There were no clinically relevant harms encountered.

CONCLUSIONS

A future definitive trial exploring the effectiveness of subcutaneous infusion of ketamine for major depressive disorder in the palliative care setting may be feasible by addressing identified study barriers. Individual dose-titration of subcutaneous ketamine infusions over two hours from 0.1mg/kg can be well-tolerated and appears to produce transient antidepressant signals over hours to days.

Courtes A, Jones G, Soares JC, Machado-Vieira R. Pharmacotherapies Targeting GABA-Glutamate Neurotransmission for Treatment-Resistant Depression

Treatment-resistant depression (TRD) is a term used to describe a particular type of major depressive disorder (MDD). There is no consensus about what defines TRD, with various studies describing between 1 and 4 failures of antidepressant therapies, with or without electroconvulsive therapy (ECT). That is why TRD is such a growing concern among clinicians and researchers, and it explains the necessity for investigating novel therapeutic targets beyond conventional monoamine pathways. An imbalance between two primary central nervous system (CNS) neurotransmitters, L-glutamate and γ-aminobutyric acid (GABA), has emerged as having a key role in the pathophysiology of TRD. In this review, we provide an evaluation and comprehensive review of investigational antidepressants targeting these two systems, accessing their levels of available evidence, mechanisms of action, and safety profiles. N-methyl-D-aspartate (NMDA) receptor antagonism has shown the most promise amongst the glutamatergic targets, with ketamine and esketamine (Spravato) robustly generating responses across trials. Two specific NMDA-glycine site modulators, D-cycloserine (DCS) and apimostinel, have also generated promising initial safety and efficacy profiles, warranting further investigation. Combination dextromethorphan-bupropion (AXS-05/Auvelity) displays a unique mechanism of action and demonstrated positive results in particular applicability in subpopulations with cognitive dysfunction. Currently, the most promising GABA modulators appear to be synthetic neurosteroid analogs with positive GABAA receptor modulation (such as brexanolone). Overall, advances in the last decade provide exciting perspectives for those who do not improve with conventional therapies. Of the compounds reviewed here, three are approved by the Food and Drug Administration (FDA): esketamine (Spravato) for TRD, Auvelity (dextromethorphan-bupropion) for major depressive disorder (MDD), and brexanolone (Zulresso) for post-partum depression (PPD). Notably, some concerns have arisen with esketamine and brexanolone, which will be detailed in this study.

Transcranial magnetic stimulation and ketamine: implications for combined treatment in depression

Drug-resistant mental disorders, particularly treatment-resistant depression, pose a significant medical and social problem. To address this challenge, modern psychiatry is constantly exploring the use of novel treatment methods, including biological treatments, such as transcranial magnetic stimulation (TMS), and novel rapid-acting antidepressants, such as ketamine. While both TMS and ketamine demonstrate high effectiveness in reducing the severity of depressive symptoms, some patients still do not achieve the desired improvement. Recent literature suggests that combining these two methods may yield even stronger and longer-lasting results. This review aims to consolidate knowledge in this area and elucidate the potential mechanisms of action underlying the increased efficacy of combined treatment, which would provide a foundation for the development and optimization of future treatment protocols.

The Study of Ketamine for Youth Depression (SKY-D): study protocol for a randomised controlled trial of low-dose ketamine for young people with major depressive disorder

BACKGROUND

Existing treatments for young people with severe depression have limited effectiveness. The aim of the Study of Ketamine for Youth Depression (SKY-D) trial is to determine whether a 4-week course of low-dose subcutaneous ketamine is an effective adjunct to treatment-as-usual in young people with major depressive disorder (MDD).

METHODS

SKY-D is a double-masked, randomised controlled trial funded by the Australian Government's National Health and Medical Research Council (NHMRC). Participants aged between 16 and 25 years (inclusive) with moderate-to-severe MDD will be randomised to receive either low-dose ketamine (intervention) or midazolam (active control) via subcutaneous injection once per week for 4 weeks. The primary outcome is change in depressive symptoms on the Montgomery-Åsberg Depression Rating Scale (MADRS) after 4 weeks of treatment. Further follow-up assessment will occur at 8 and 26 weeks from treatment commencement to determine whether treatment effects are sustained and to investigate safety outcomes.

DISCUSSION

Results from this trial will be important in determining whether low-dose subcutaneous ketamine is an effective treatment for young people with moderate-to-severe MDD. This will be the largest randomised trial to investigate the effects of ketamine to treat depression in young people.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ID: ACTRN12619000683134. Registered on May 7, 2019. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377513 .

Subanesthetic Ketamine Infusion Reducing Symptoms of Depression in a Patient With End-Stage Heart Failure Enrolled in Hospice Care: A Case Report

Background: The development of major depressive disorder in patients at end of life often goes undiagnosed, as it is difficult to distinguish from preparatory grief and/or hypoactive delirium in this unique patient population. If this preliminary barrier of appropriate diagnosis is overcome, it can be quite difficult to properly select and adjust pharmacological therapy. Many well-established antidepressants take four to five weeks for maximal effectiveness (which may be far too long of a titration period for patients at end of life), have various contraindications to patients' comorbid chronic conditions (particularly patients with cardiovascular disease), or may simply be ineffective. Case: We present a case report of severe treatment-resistant depression in an end-stage heart failure patient enrolled in hospice care. Discussion: We discuss the potential use of a single low-dose intravenous racemic ketamine infusion to reduce end-of-life suffering related to depression, despite the theoretical contraindication of ketamine use in such patients, in part, due to its sympathomimetic secondary effect.

Activation of σ1-Receptors by R-Ketamine May Enhance the Antidepressant Effect of S-Ketamine

Ketamine is a racemic mixture composed of two enantiomers, S-ketamine and R-ketamine. In preclinical studies, both enantiomers have exhibited antidepressant effects, but these effects are attributed to distinct pharmacological activities. The S-enantiomer acts as an NMDA-channel blocker and as an opioid μ-receptor agonist, whereas the R-enantiomer binds to σ1-receptors and is believed to act as an agonist. As racemate, ketamine potentially triggers four biochemical pathways involving the AGC-kinases, PKA, Akt (PKB), PKC and RSK that ultimately lead to inhibitory phosphorylation of GSK3β in microglia. In patients with major depressive disorder, S-ketamine administered as a nasal spray has shown clear antidepressant activity. However, when compared to intravenously infused racemic ketamine, the response rate, duration of action and anti-suicidal activity of S-ketamine appear to be less pronounced. The σ1-protein interacts with μ-opioid and TrkB-receptors, whereas in preclinical experiments σ1-agonists reduce μ-receptor desensitization and improve TrkB signal transduction. TrkB activation occurs as a response to NMDA blockade. So, the σ1-activity of R-ketamine may not only enhance two pathways via which S-ketamine produces an antidepressant response, but it furthermore provides an antidepressant activity in its own right. These two factors could explain the apparently superior antidepressant effect observed with racemic ketamine compared to S-ketamine alone.

Predicting outcome with Intranasal Esketamine treatment: A machine-learning, three-month study in Treatment-Resistant Depression (ESK-LEARNING)

Treatment-resistant depression (TRD) represents a severe clinical condition with high social and economic costs. Esketamine Nasal Spray (ESK-NS) has recently been approved for TRD by EMA and FDA, but data about predictors of response are still lacking. Thus, a tool that can predict the individual patients' probability of response to ESK-NS is needed. This study investigates sociodemographic and clinical features predicting responses to ESK-NS in TRD patients using machine learning techniques. In a retrospective, multicentric, real-world study involving 149 TRD subjects, psychometric data (Montgomery-Asberg-Depression-Rating-Scale/MADRS, Brief-Psychiatric-Rating-Scale/BPRS, Hamilton-Anxiety-Rating-Scale/HAM-A, Hamilton-Depression-Rating-Scale/HAMD-17) were collected at baseline and at one month/T1 and three months/T2 post-treatment initiation. We trained three different random forest classifiers, able to predict responses to ESK-NS with accuracies of 68.53% at T1 and 66.26% at T2 and remission at T2 with 68.60% of accuracy. Features like severe anhedonia, anxious distress, mixed symptoms as well as bipolarity were found to positively predict response and remission. At the same time, benzodiazepine usage and depression severity were linked to delayed responses. Despite some limitations (i.e., retrospective study, lack of biomarkers, lack of a correct interrater-reliability across the different centers), these findings suggest the potential of machine learning in personalized intervention for TRD.

A Comprehensive Overview of the Role of Visual Cortex Malfunction in Depressive Disorders: Opportunities and Challenges

Major depressive disorder (MDD) is a highly heterogeneous mental disorder, and its complex etiology and unclear mechanism are great obstacles to the diagnosis and treatment of the disease. Studies have shown that abnormal functions of the visual cortex have been reported in MDD patients, and the actions of several antidepressants coincide with improvements in the structure and synaptic functions of the visual cortex. In this review, we critically evaluate current evidence showing the involvement of the malfunctioning visual cortex in the pathophysiology and therapeutic process of depression. In addition, we discuss the molecular mechanisms of visual cortex dysfunction that may underlie the pathogenesis of MDD. Although the precise roles of visual cortex abnormalities in MDD remain uncertain, this undervalued brain region may become a novel area for the treatment of depressed patients.

Anhedonia and Depressive Disorders

Anhedonia is a core symptom of depression and of several psychiatric disorders. Anhedonia has however expanded from its original definition to encompass a spectrum of reward processing deficits that received much interest in the last decades. It is a relevant risk factor for possible suicidal behaviors, and that it may operate as an independent risk factor for suicidality apart from the episode severity. Anhedonia has also been linked to inflammation with a possible reciprocal deleterious effect on depression. Its neurophysiological bases mainly include alterations in striatal and prefrontal areas, with dopamine being the most involved neurotransmitter. Anhedonia is thought to have a significant genetic component and polygenic risk scores are a possible tool for predicting an individual's risk for developing anhedonia. Traditional antidepressants, such as selective serotonin reuptake inhibitors, showed a limited benefit on anhedonia, also considering their potential pro-anhedonic effect in some subjects. Other treatments may be more effective in treating anhedonia, such as agomelatine, vortioxetine, ketamine and transcranial magnetic stimulation. Psychotherapy is also widely supported, with cognitive-behavioral therapy and behavioral activation both showing benefit. In conclusion, a large body of evidence suggests that anhedonia is, at least partially, independent from depression, therefore it needs careful assessment and targeted treatment.

Intraoperative Esketamine Is Effective at Reducing Acute Postoperative Pain in Bariatric Surgery Patients: a Randomized Control Trial

BACKGROUND

The analgesic effect and postoperative effects of esketamine are not yet clear in bariatric surgeries. Many bariatric surgery patients suffer from acute abdominal pain after surgery which leads to increased opioid use. This study aimed to determine whether intraoperative use of esketamine could reduce acute postoperative pain in bariatric surgery patients.

METHODS

We designed a randomized double-blinded controlled trial. Included patients between the ages of 18 and 50 years with a body mass index ≥27 kg/m2 and American Society of Anesthesiologists Physical Status of I-III, scheduled to undergo sleeve gastrectomy. We divided them into two groups, the control group which received a placebo, and the esketamine group which received a loading dose of esketamine 0.2 mg/kg and a maintenance dose of 0.2 mg/(kg·h) along with other anesthetic drugs during the surgery. After the surgery, they were assessed for Numerical Rating Scale (NRS) pain scores and Post Operative Nausea and Vomiting (PONV) scores, while other surgical data were recorded during the surgery.

RESULTS

We enrolled 68 patients, 52 females, and 16 males. The 0.5 h, 1 h, 2 h, 6 h, and 12 h NRS scores were significantly lower in the esketamine group compared to the control group, and the extra painkillers administered were significantly lower in the esketamine group (p<0.05).

CONCLUSION

Intraoperative use of esketamine can reduce acute postoperative pain in bariatric surgery patients. Further studies should explore whether the reduced pain is due to the anti-depressive effect of esketamine or purely the analgesic effect.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2100054038, https://www.chictr.org.cn/com/25/showproj.aspx?proj=142806 ).

Therapeutic and Safety Outcomes of Intravenous Ketamine for Treatment-refractory Depression in a Veteran Population: A Case Series

INTRODUCTION

Major depressive disorder is a serious, recurrent, and disabling psychiatric illness. Despite many proven treatments with multiple medications or therapies, approximately 30% of patients fail to achieve remission and are considered to have treatment-refractory depression (TRD). Recently, there has been a growing interest in the use of intravenous (IV) ketamine for the treatment of TRD. There is limited yet increasing evidence to support the use of ketamine, a glutamate receptor antagonist, in the management of depression; however, the lack of data regarding the safety and tolerability of therapy has limited its clinical use. By analyzing a cohort of veterans with TRD and comorbid psychiatric conditions treated with IV ketamine infusions for a 24-month study period, we aim to provide critical information about ketamine's clinical effectiveness and safety.

MATERIALS AND METHODS

Based on a retrospective chart review, we identified eight veterans with TRD receiving treatment with repeated-dose IV ketamine from 2018 to 2020. The magnitude of clinical response was based on the Beck Depression Inventory self-report scale and the Patient Health Questionnaire-9, both measured at the initial patient consultation and before the beginning of each ketamine infusion treatment. Safety analysis included changes to pre- and post-ketamine infusion on vital signs, effects on alertness and sedation, and potential psychosis-like effects. For all outcomes, we estimated a linear mixed-effects model that allowed heterogeneous residual variances for each veteran. The effect of continuous predictor variables was estimated using restricted cubic splines with knot points specified at the 5th, 35th, 65th, and 95th percentiles. All the analyses were conducted using SAS v.9.4, with P < .05 indicating the statistical significance. This study had institutional review board approval: 1220.

RESULTS

During the study period, the median number of ketamine infusions was 15 across a median of 164 days of treatment follow-up with a median time between ketamine infusions of 4 days. For both Beck Depression Inventory and Patient Health Questionnaire-9 scores, there was a statistically significant reduction across infusions (both P < .001), but the strongest reduction occurred before day 40. The change was statistically significant for decreased heart rate (P = .019) but not for systolic blood pressure (P = .612), diastolic blood pressure (P = .942), respiratory rate (P = .822), oxygen saturation (P = .070), and temperature (P = .943). Side effects were reported in six patients (75%); however, the only side effect reported was excessive sedation or dizziness immediately after infusion.

CONCLUSIONS

In this study, repeated-dose IV ketamine infusions over a 24-month study period resulted in a significant reduction in depression scores in a group of veterans with TRD. The rapid onset of significant response, absence of psychosis-like effects or dissociative symptoms despite psychiatric comorbidities, and minimal effects on vital signs support the clinical efficacy and safety of this exciting new treatment option for patients with TRD. Limitations include a 2-year study period, lack of information on long-term effects, and the retrospective nature of the study. Prospective studies of longer duration are needed to assess the long-term efficacy and safety of IV ketamine for TRD.

Can old drugs learn new tricks? Achieving registration and public subsidy listing for off-patent medicines with novel therapeutic applications

With the increasing costs of drug development, repurposing of low-cost medicines for new indications has never been more important. However, there are multiple barriers to repurposing, particularly for off-patent medicines, and limited incentives for the pharmaceutical industry to sponsor registration and public subsidy listing. Here, we explore these barriers and their consequences and provide examples of successful repurposing strategies.

Dysfunction of GluN3A subunit is involved in depression-like behaviors through synaptic deficits

BACKGROUND

N-methyl-d-aspartate receptor (NMDAR) has been implicated in the pathophysiology of depression. However, as the unique inhibitory subunit of NMDARs, the role of GluN3A in depression is largely unclear.

METHODS

Firstly, expression of GluN3A was examined in a mouse model of depression induced by chronic restraint stress (CRS). Then, rescue experiment with rAAV-Grin3a injection into hippocampus of CRS mice was carried out. Lastly, GluN3A knockout (KO) mouse was generated via CRISPR/Cas9 technique, and the molecular mechanism underlying involvement of GluN3A in depression was initially explored using RNA-seq technique, RT-PCR and western blotting.

RESULTS

GluN3A expression in hippocampus was significantly decreased in CRS mice. Depression-like behaviors induced by CRS were ameliorated when the decrease of GluN3A expression in mice exposed to CRS was restored. GluN3A KO mice exhibited symptoms of anhedonia reported as reduced sucrose preference, and symptoms of despair assayed by a longer immobility time in FST. Transcriptome analysis revealed genetic ablation of GluN3A was associated with downregulation of genes implicated in synapse and axon development. Postsynaptic protein PSD95 was decreased in GluN3A KO mice. More importantly, reduction of PSD95 in CRS mice can be rescued by viral mediated Grin3a re-expression.

LIMITATIONS

The mechanism underlying GluN3A involvement in depression is not fully determined.

CONCLUSIONS

Our data suggested that GluN3A dysfunction is involved in depression, which might be mediated by synaptic deficits. These findings will facilitate the understanding of the role of GluN3A in depression, and they might provide a new strategy for the development of subunit-selective NMDAR antagonists as antidepressant drugs.

Suicide prevention and ketamine: insights from computational modeling

Suicide is a pressing public health issue, with over 700,000 individuals dying each year. Ketamine has emerged as a promising treatment for suicidal thoughts and behaviors (STBs), yet the complex mechanisms underlying ketamine's anti-suicidal effect are not fully understood. Computational psychiatry provides a promising framework for exploring the dynamic interactions underlying suicidality and ketamine's therapeutic action, offering insight into potential biomarkers, treatment targets, and the underlying mechanisms of both. This paper provides an overview of current computational theories of suicidality and ketamine's mechanism of action, and discusses various computational modeling approaches that attempt to explain ketamine's anti-suicidal effect. More specifically, the therapeutic potential of ketamine is explored in the context of the mismatch negativity and the predictive coding framework, by considering neurocircuits involved in learning and decision-making, and investigating altered connectivity strengths and receptor densities targeted by ketamine. Theory-driven computational models offer a promising approach to integrate existing knowledge of suicidality and ketamine, and for the extraction of model-derived mechanistic parameters that can be used to identify patient subgroups and personalized treatment approaches. Future computational studies on ketamine's mechanism of action should optimize task design and modeling approaches to ensure parameter reliability, and external factors such as set and setting, as well as psychedelic-assisted therapy should be evaluated for their additional therapeutic value.

The use of esketamine in the treatment of patients with oral antidepressant-resistant depression: systematic review and meta-analysis

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field to standardize how to conduct, and to assist in the reasoning and decision-making of doctors. The information provided by this project must be critically evaluated by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical condition of each patient. Guideline conclusion: April 2023. Societies: Brazilian Medical Association.

Arketamine for bipolar depression: Open-label, dose-escalation, pilot study

There are significantly fewer options for the treatment of bipolar depression than major depressive disorder, with an urgent need for alternative therapies. In this pilot study, we treated six subjects with bipolar disorder types I and II (according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria) who had been in a current depressive episode for at least four weeks. Four subjects were female (66.66%), and the mean age was 45.33 (±12.32). Subjects received adjunct treatment with two arketamine intravenous infusions one week apart-0.5 mg/kg first and then 1 mg/kg. The mean baseline Montgomery-Åsberg Depression Rating Scale (MADRS) total score was 36.66, which decreased to 27.83 24h after the first infusion of 0.5 mg/kg of arketamine (p = 0.036). In respect of the 1 mg/kg dose, the mean MADRS total score before the second infusion was 32.0, which dropped to 17.66 after 24h (p < 0.001). Arketamine appears to have rapid-acting antidepressant properties, consistent with previous animal studies on major depression. All individuals tolerated both doses, exhibiting nearly absent dissociation, and no manic symptoms. To the best of our knowledge, this pilot trial is the first to test the feasibility and safety of the (R)-enantiomer of ketamine (arketamine) for bipolar depression.

Pharmacotherapy: Ketamine and Esketamine

Ketamine and esketamine have rapid-onset antidepressant effects and may be considered for the management of treatment-resistant depression. Intranasal esketamine has regulatory approval in the United States and European Union. Intravenous ketamine is often administered off-label as an antidepressant, though no standard operating procedures exist. Repeated administrations and the use of a concurrent standard antidepressant may maintain antidepressant effects of ketamine/esketamine. Possible adverse effects of ketamine and esketamine include psychiatric, cardiovascular, neurologic and genitourinary effects, and the potential for abuse. The long-term safety and efficacy of ketamine/esketamine as antidepressants require further study.

The antidepressant actions of ketamine and its enantiomers

Ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist first developed as an anesthetic, has shown significant promise as a medication with rapid antidepressant properties in treatment-resistant depression. However, concerns such as adverse side effects and potential misuse liability have limited its widespread use. Racemic ketamine has two enantiomers-(S)- and (R)-ketamine-that appear to have disparate underlying mechanisms. This brief review summarizes some of the most recent preclinical and clinical research regarding the convergent and divergent prophylactic, immediate, and sustained antidepressant effects of (S)- and (R)-ketamine while addressing potential differences in their side effect and misuse liability profiles. Preclinical research suggests divergent mechanisms underlying (S)- and (R)-ketamine, with (S)-ketamine more directly affecting mechanistic target of rapamycin complex 1 (mTORC1) signaling and (R)-ketamine more directly affecting extracellular signal-related kinase (ERK) signaling. Clinical research suggests that (R)-ketamine has a milder side effect profile than (S)-ketamine and decreases depression rating scale scores, but recent randomized, controlled trials found that it had no significant antidepressant efficacy compared to placebo, suggesting that caution is warranted in interpreting its therapeutic potential. Future preclinical and clinical research is needed to maximize the efficacy of each enantiomer, either by optimizing dose, route of administration, or administration paradigm.

Case report: Intramuscular ketamine or intranasal esketamine as a treatment in four patients with major depressive disorder and comorbid anorexia nervosa

Introduction

A comorbid diagnosis of a depressive disorder is a negative prognostic factor for individuals with AN, and novel treatments are needed to target depressive symptoms in this population. One emerging promising treatment for depressive disorders is ketamine, although there is less research investigating the use of ketamine for alleviating depression in people with AN.

Case report

This study reports on four patients with a lifetime diagnosis of AN and a comorbid diagnosis of major depressive disorder who received either intramuscular ketamine (n = 2) or intranasal esketamine (n = 2) treatment from a private psychiatric clinic. Depressive symptomatology (PHQ-9) was measured prior to (es)ketamine administration on every dosing session and adverse effects were recorded during and after dosing. All patients reported a subjective decrease in depression, although only those administered intranasal esketamine showed a reduction in PHQ-9 depression scores over time. Number of doses ranged from 3 to 23. All patients tolerated treatment well and no serious adverse effects emerged, however nausea/vomiting was experienced by one patient on one dosing session. Weight remained stable in all cases, although notably across all patients, weight at the beginning of treatment was within a "healthy" range.

Discussion

These findings suggest that (es)ketamine may reduce depressive symptoms in people with major depressive disorder and a comorbid diagnosis of AN. Future feasibility and pilot trials are warranted in order to elicit robust data on efficacy, acceptability, safety and tolerability.

Evaluation of clinical effects of Esketamine on depression in patients with missed miscarriage: A randomized, controlled, double-blind trial

BACKGROUND

Patients with missed miscarriages are usually accompanied by varying degrees of depression, which is closely related to the patient's prognosis. We investigated whether Esketamine could alleviate postoperative depression symptoms in patients with missed miscarriages who underwent painless curettage.

METHODS

This study was a randomized, parallel-controlled, double-blind, single-center trial. A total of 105 patients with preoperative 1d (EPDS) ≥ 10 were randomly assigned to the Propofol; Dezocine; Esketamine group. Patients record EPDS at 7 and 42 days after the operation. Secondary outcomes included VAS for 1 h postoperation, total propofol usage, adverse reactions, And the expressions of inflammatory factors of TNF-α, IL-1β, IL-6, IL-8, and IL-10.

RESULTS

Compared with the P and D group, patients in the S group had lower EPDS scores at 7 day (8.63 ± 3.14, 9.17 ± 3.23 vs. 6.34 ± 2.87 P = 0.0005) and 42 days (9.40 ± 2.67, 8.49 ± 3.05 vs.5.31 ± 2.49 P < 0.0001) after the operation. Respectively, Compared with the P group, the VAS scores (3.51 ± 1.12 vs. 2.80 ± 0.83, 2.40 ± 0.81, P = 0.0035) and the dosage of propofol used during operation (198.7 ± 47.48 vs. 145.5 ± 19.31, 142.9 ± 21.01 P < 0.0001) were lower in the D and S groups, and lower postoperative inflammatory response at 1 day after surgery. Other outcomes among the three groups were not found to the difference.

CONCLUSIONS

Esketamine effectively treated postoperative depressive symptoms of patients with a missed miscarriage, decreasing propofol consumption and inflammatory response.

ERAS Protocol Options for Perioperative Pain Management of Substance Use Disorder in the Ambulatory Surgical Setting

Even prior to the COVID-19 pandemic, rates of ambulatory surgeries and ambulatory patients presenting with substance use disorder were increasing, and the end of lockdown has further catalyzed the increasing rates of ambulatory patients presenting for surgery with substance use disorder (SUD). Certain subspecialty groups of ambulatory procedures have already established protocols to optimize early recovery after surgery (ERAS), and these groups have subsequently enjoyed improved efficiency and reduced adverse outcomes as a result. In this present investigation, we review the literature as it relates to substance use disorder patients, with a particular focus on pharmacokinetic and pharmacodynamic profiles, and their resulting impact on the acute- or chronic user ambulatory patient. The systematic literature review findings are organized and summarized. We conclude by identifying areas of opportunity for further study, specifically with the aim of developing a dedicated ERAS protocol for substance use disorder patients in the ambulatory surgery setting. - Healthcare in the USA has seen an increase in rates of both substance use disorder patients and separately in ambulatory surgery cases. - Specific perioperative protocols to optimize outcomes for patients who suffer from substance use disorder have been described in recent years. - Agents of interest like opioids, cannabis, and amphetamines are the top three most abused substances in North America. - A protocol and recommend further work should be done to integrate with concrete clinical data, in which strategies should be employed to confer benefits to patient outcomes and hospital quality metrics like those enjoyed by ERAS protocol in other settings.

Pharmacological Mechanism of Ketamine in Suicidal Behavior Based on Animal Models of Aggressiveness and Impulsivity: A Narrative Review

Around 700,000 people die from suicide each year in the world. Approximately 90% of suicides have a history of mental illness, and more than two-thirds occur during a major depressive episode. Specific therapeutic options to manage the suicidal crisis are limited and measures to prevent acting out also remain limited. Drugs shown to reduce the risk of suicide (antidepressants, lithium, or clozapine) necessitate a long delay of onset. To date, no treatment is indicated for the treatment of suicidality. Ketamine, a glutamate NMDA receptor antagonist, is a fast-acting antidepressant with significant effects on suicidal ideation in the short term, while its effects on suicidal acts still need to be demonstrated. In the present article, we reviewed the literature on preclinical studies in order to identify the potential anti-suicidal pharmacological targets of ketamine. Impulsive-aggressive traits are one of the vulnerability factors common to suicide in patients with unipolar and bipolar depression. Preclinical studies in rodent models with impulsivity, aggressiveness, and anhedonia may help to analyze, at least in part, suicide neurobiology, as well as the beneficial effects of ketamine/esketamine on reducing suicidal ideations and preventing suicidal acts. The present review focuses on disruptions in the serotonergic system (5-HT_B receptor, MAO-A enzyme), neuroinflammation, and/or the HPA axis in rodent models with an impulsive/aggressive phenotype, because these traits are critical risk factors for suicide in humans. Ketamine can modulate these endophenotypes of suicide in human as well as in animal models. The main pharmacological properties of ketamine are then summarized. Finally, numerous questions arose regarding the mechanisms by which ketamine may prevent an impulsive-aggressive phenotype in rodents and suicidal ideations in humans. Animal models of anxiety/depression are important tools to better understand the pathophysiology of depressed patients, and in helping develop novel and fast antidepressant drugs with anti-suicidal properties and clinical utility.

Designing Clinical Trials to Assess the Impact of Pharmacological Treatment for Suicidal Ideation/Behavior: Issues and Potential Solutions

Suicide is a serious and growing public health concern yet randomized controlled trials (RCTs) that inform pharmacologic treatment remain limited. We emphasize the overall need for such trials and review the literature to highlight examples of trials that have aimed to study patients at elevated risk of suicide. We discuss key examples of existing psychotropic medication trials as well as psychotherapy intervention studies that can yield important design insights. Medications that have been studied in individuals at risk for suicide include lithium, clozapine, zolpidem, prazosin, ketamine, esketamine, and aripiprazole. While important design challenges should be considered-RCTs to study suicide are feasible and much needed. Issues such as overall trial design, patient-selection criteria, and the scales/tools used to assess suicidality are discussed.

Diagnosis and management of bipolar disorders

Bipolar disorders (BDs) are recurrent and sometimes chronic disorders of mood that affect around 2% of the world's population and encompass a spectrum between severe elevated and excitable mood states (mania) to the dysphoria, low energy, and despondency of depressive episodes. The illness commonly starts in young adults and is a leading cause of disability and premature mortality. The clinical manifestations of bipolar disorder can be markedly varied between and within individuals across their lifespan. Early diagnosis is challenging and misdiagnoses are frequent, potentially resulting in missed early intervention and increasing the risk of iatrogenic harm. Over 15 approved treatments exist for the various phases of bipolar disorder, but outcomes are often suboptimal owing to insufficient efficacy, side effects, or lack of availability. Lithium, the first approved treatment for bipolar disorder, continues to be the most effective drug overall, although full remission is only seen in a subset of patients. Newer atypical antipsychotics are increasingly being found to be effective in the treatment of bipolar depression; however, their long term tolerability and safety are uncertain. For many with bipolar disorder, combination therapy and adjunctive psychotherapy might be necessary to treat symptoms across different phases of illness. Several classes of medications exist for treating bipolar disorder but predicting which medication is likely to be most effective or tolerable is not yet possible. As pathophysiological insights into the causes of bipolar disorders are revealed, a new era of targeted treatments aimed at causal mechanisms, be they pharmacological or psychosocial, will hopefully be developed. For the time being, however, clinical judgment, shared decision making, and empirical follow-up remain essential elements of clinical care. This review provides an overview of the clinical features, diagnostic subtypes, and major treatment modalities available to treat people with bipolar disorder, highlighting recent advances and ongoing therapeutic challenges.

The Missing Piece? A Case for Microglia's Prominent Role in the Therapeutic Action of Anesthetics, Ketamine, and Psychedelics

There is much excitement surrounding recent research of promising, mechanistically novel psychotherapeutics - psychedelic, anesthetic, and dissociative agents - as they have demonstrated surprising efficacy in treating central nervous system (CNS) disorders, such as mood disorders and addiction. However, the mechanisms by which these drugs provide such profound psychological benefits are still to be fully elucidated. Microglia, the CNS's resident innate immune cells, are emerging as a cellular target for psychiatric disorders because of their critical role in regulating neuroplasticity and the inflammatory environment of the brain. The following paper is a review of recent literature surrounding these neuropharmacological therapies and their demonstrated or hypothesized interactions with microglia. Through investigating the mechanism of action of psychedelics, such as psilocybin and lysergic acid diethylamide, ketamine, and propofol, we demonstrate a largely under-investigated role for microglia in much of the emerging research surrounding these pharmacological agents. Among others, we detail sigma-1 receptors, serotonergic and γ-aminobutyric acid signalling, and tryptophan metabolism as pathways through which these agents modulate microglial phagocytic activity and inflammatory mediator release, inducing their therapeutic effects. The current review includes a discussion on future directions in the field of microglial pharmacology and covers bidirectional implications of microglia and these novel pharmacological agents in aging and age-related disease, glial cell heterogeneity, and state-of-the-art methodologies in microglial research.

Pharmacologic Approaches to Suicide Prevention

Suicide is a leading cause of death that is often preventable. This article reviews the role of medications in treating suicidal behavior and in preventing suicide. For an acute suicidal crisis, ketamine, and perhaps esketamine, are emerging as important tools. For patients with chronic suicidality, clozapine remains the only U.S. Food and Drug Administration (FDA) approved antisuicidal medication, and its use is predominantly for patients with schizophrenia and schizoaffective disorder. An abundance of literature supports the use of lithium among patients with mood disorders, including those with major depressive disorder. Despite the black box warning regarding antidepressants and suicide risk among children, adolescents, and young adults, antidepressants are widely used and remain helpful in reducing suicidal thoughts and behaviors, primarily among patients with mood disorders. Treatment guidelines focus on the importance of optimizing treatment of the psychiatric conditions known to be associated with suicide risk. For patients with these conditions, the authors recommend focusing on suicide as an independent treatment target and using an enhanced medication management strategy that includes maintaining a supportive, nonjudgmental therapeutic relationship; flexibility; collaboration; measurement-based care; consideration of combining medications with nonpharmacologic, evidence-based strategies; and ongoing safety planning.

Efficacy, Tolerability, and Safety of Toludesvenlafaxine for the Treatment of Major Depressive Disorder-A Narrative Review

The estimated rate of treatment-resistant major depressive disorder (TRD) remains higher than 30%, even after the discovery of multiple classes of antidepressants in the last 7 decades. Toludesvenlafaxine (ansofaxine, LY03005, or LPM570065) is a first-in-class triple monoaminergic reuptake inhibitor (TRI) that has reached clinical use. The objective of this narrative review was to summarize clinical and preclinical evidence about the efficacy, tolerability, and safety of toludesvenlafaxine. Based on the results of 17 reports retrieved in the literature, the safety and tolerability profiles of toludesvenlafaxine were good in all clinical trials, and the pharmacokinetic parameters were well described in the phase 1 trials. The efficacy of toludesvenlafaxine was demonstrated in one phase 2 and one phase 3 trial, both on primary and secondary outcomes. In conclusion, this review highlights the favorable clinical results of toludesvenlafaxine in only two short-term trials that enrolled patients with major depressive disorder (MDD) (efficacy and tolerability were good for up to eight weeks), indicating the need for more good quality, larger-sample, and longer-term trials. Exploring new antidepressants, such as TRI, can be considered a priority for clinical research due to the high rates of TRD, but also due to the significant percentages of relapse in patients with MDD.

The NMDA receptor antagonists memantine and ketamine as anti-migraine agents

Migraine is a debilitating disorder affecting females more frequently than males. There is some evidence that drugs targeting glutamate receptors: memantine and ketamine might be beneficial in the therapy of this entity. Therefore, the purpose of this work is to present NMDA receptor antagonists, memantine and ketamine, as potential anti-migraine agents. We searched PubMed/MEDLINE, Embase, and clinical trials submitted to ClinicalTrials.gov to find publications describing eligible trials published between database inception and December 31, 2021. This comprehensive literature review summarizes data on the use of the NMDA receptor antagonists memantine and ketamine in the pharmacotherapy of migraine. Results from 20 previous and recent preclinical experiments are discussed and correlated with 19 clinical trials (including case series, open-label, and randomized placebo-controlled trials). For the purposes of this review, the authors hypothesized that the propagation of SD is a major mechanism in the pathophysiology of migraine. In several animal studies and in vitro studies, memantine and ketamine inhibited or reduced propagation of the SD. In addition, the results of clinical trials suggest that memantine or ketamine may be an effective treatment option for migraine. However, most studies on these agents lack control group. Although further clinical trials are needed, the results suggest that ketamine or memantine may be promising molecules for the treatment of severe migraine. Particular attention should be paid to people who have a treatment-resistant form of migraine with aura or have exhausted existing treatment options. For them, the drugs under discussion could represent an interesting alternative in the future.

Arketamine as adjunctive therapy for treatment-resistant depression: A placebo-controlled pilot study

BACKGROUND

Racemic ketamine is a mixture of (R)-ketamine (arketamine) and (S)-ketamine (esketamine), with the latter regarded as the main isomer for antidepressant effects. However, preclinical data and one open-label human trial suggest arketamine might exert a more potent and longer-lasting antidepressant effect with fewer side effects. We aimed to explore the feasibility of a randomized controlled trial of arketamine for treatment-resistant depression (TRD) and to assess its efficacy and safety compared to placebo.

METHODS

This is a, randomized, double-blind, crossover, pilot trial (n = 10). All participants received saline and arketamine (0.5 mg/kg) with a one-week interval. Treatment effects were analyzed with a linear mixed effects (LME) model.

RESULTS

Our analysis suggested the presence of a carryover effect, so the main efficacy analysis was limited to the first week, which demonstrated a main effect of time (p = 0.038) but not for treatment (p = 0.40) or their interaction (p = 0.95). This indicates that depression improved over time, but without significant difference between arketamine and placebo. Analyzing the two weeks together, findings were the same. Dissociation and other adverse events were minimal.

LIMITATIONS

This was a pilot study with a small sample and underpowered.

CONCLUSIONS

Arketamine was not superior to placebo for TRD but demonstrated to be extremely safe. Our findings reinforce the importance of continuing studies with this drug, with better powered clinical trials, perhaps considering a parallel design with higher or flexible doses and repeated administrations.

Effect of pre-administration of esketamine intraoperatively on postpartum depression after cesarean section: A randomized, double-blinded controlled trial

BACKGROUND

To evaluate the effect of pre-administration of esketamine intraoperatively on the occurrence of postpartum depression after cesarean section under combined spinal-epidural anesthesia.

METHODS

A total of 120 women aged 24 to 36 years undergoing cesarean section by spinal-epidural anesthesia with American Society of Anesthesiologists physical status II were enrolled. According to the intraoperative use of esketamine, all participants were randomly divided into 2 groups: test group (group E) and control group (group C). Esketamine was administered intravenously at a dose of 0.2 mg/kg after the infant was delivered in group E and equal volume of normal saline was given in group C. The incidence of postpartum depression was recorded at 1 week and 6 weeks after the operation. The occurrence of adverse reactions such as postpartum bleeding, nausea and vomiting, drowsiness, and nightmares were also recorded at 48 hours after surgery.

RESULTS

Compared with group C, the incidence of postpartum depression was significantly lower at 1 week and 6 weeks after surgery in group E (P < .01). There was no significant difference of the adverse effects at 48 hours after the operation between the 2 groups.

CONCLUSION

Intravenous infusion of 0.2 mg/kg esketamine in women during cesarean section can significantly reduce the incidence of postpartum depression at 1 week and 6 weeks after surgery without increasing related adverse effects.

Real-world effectiveness of repeated ketamine infusions for treatment-resistant bipolar depression

BACKGROUND

Clinical trials have demonstrated rapid antidepressant effects with intravenous (IV) ketamine for major depressive disorder, with relatively less research specifically for bipolar depression. Herein, we describe the real-world effectiveness of repeated ketamine infusions for treatment-resistant bipolar depression.

METHODS

This study was conducted in a community clinic in Mississauga, Ontario (Canadian Rapid Treatment Centre of Excellence; Braxia Health). In this observational study (NCT04209296), patients with treatment-resistant bipolar I/II depression (n = 66) received four sub-anesthetic doses of IV ketamine (0.5-0.75 mg/kg) over a two-week period. Symptoms of depression, suicidality, anxiety, and functioning were assessed with validated self-report measures.

RESULTS

Statistically and clinically significant antidepressant effects were observed in the overall sample, as measured by the Quick Inventory for Depression Symptomatology-Self Report-16 (QIDS-SR16 ) with further reductions in depressive symptoms observed after each subsequent infusion (n = 66; mean QIDS-SR16 reduction of 6.08+/-1.39; p < 0.0001). Significant reductions of suicidal thoughts (QIDS-SR16 -Suicide Item) and anxiety (Generalized Anxiety Disorder-7) were also observed with functional improvements on the Sheehan Disability Scale (p < 0.0001 on all measures). Moreover, the response rate (QIDS-SR16 total score decrease ≥50% from baseline) was 35% and remission rate (QIDS-SR16 total score ≤5) was 20% after four infusions. Infusions were generally well tolerated with treatment-emergent hypomania observed in only three patients (4.5%) with zero cases of mania or psychosis.

CONCLUSIONS

Real-world effectiveness of IV ketamine for bipolar depression was observed. Repeated doses were associated with greater symptom reduction and adequate tolerability.

The Quest for Secondary Pharmaceuticals: Drug Repurposing/Chiral-Switches Combination Strategy

Drug repurposing toward new medical uses and chiral switches are elements of secondary pharmaceuticals. The drug repurposing and chiral-switches strategies have mostly been applied independently in drug discovery. Drug repurposing has peaked in the search for therapeutic treatments of the Coronavirus Disease 2019 pandemic, whereas chiral switches have been overlooked. The current Perspective introduces the drug repurposing/chiral-switches combination strategy, overviewing representative cases of chiral drugs that have undergone this combination: ketamine, flurbiprofen, fenfluramine, and milnacipran. The deuterium-enabled chiral switches of racemic thalidomide analogs, a variation of the repurposing/chiral-switch combination strategy, is also included. Patenting and regulatory-exclusivity considerations of the combination strategy in the discovery of new medical uses are considered. The proposed combination creates a new synergy of its two elements, overcoming arguments against chiral switches, with better prospects for validation of patents and regulatory exclusivities. The combination strategy may be applied to chiral switches to paired enantiomers. Repurposing/chiral-switch drugs may be 'obvious-to-try'; however, their inventions may be unexpected and their patents nonobvious. Patenting repurposing/chiral-switch combination drugs is not 'evergreening', 'product hopping', and 'me-too'. The expected benefits and opportunities of the combined repurposing/chiral-switch strategy vis-à-vis its two elements are superior pharmacological properties, overcoming arguments against patent validities, challenges of chiral-switch patents, reduced expenses, shortened approval procedures, and higher expectations of regulatory exclusivities.

The therapeutic role of ketamine and esketamine in treating psychopathological domains of depression

Over the past two decades, ketamine has emerged as a novel effective and rapid-acting antidepressant. While the vast majority of studies on ketamine have focused on its ability to reduce the severity of depression broadly, its effectiveness in specific domains such as cognition, anhedonia, suicidality, and workplace/social/scholastic functionality has been neglected. Similarly, current treatments (e.g., SSRIs and SNRIs) aim to improve overall depression severity, which often results in the persistence of one or more residual symptom domains and prevents full recovery to premorbid functionality. In this review, we narratively synthesize the literature pertaining to the effectiveness of ketamine in treating key domains of depressive symptomatology (i.e., cognition, anhedonia, suicidality, and psychosocial functionality). Our findings suggest that ketamine is effective across domains varyingly, with the strongest evidence being for its ability to reduce suicidality. The rapid acting nature of ketamine further supports its use in treating suicidality and potentially preventing the completion of suicide. Evidence for the effectiveness of ketamine in other domains is weak, primarily due to a lack of robust studies specifically designed to assess these domains as primary outcomes. Future studies should scrutinize the effects of ketamine on specific domains of depression to optimize its implementation.

The Utility of Amino Acid Metabolites in the Diagnosis of Major Depressive Disorder and Correlations with Depression Severity

Major depressive disorder (MDD) is a highly prevalent and disabling condition with a high disease burden. There are currently no validated biomarkers for the diagnosis and treatment of MDD. This study assessed serum amino acid metabolite changes between MDD patients and healthy controls (HCs) and their association with disease severity and diagnostic utility. In total, 70 MDD patients and 70 HCs matched in age, gender, and ethnicity were recruited for the study. For amino acid profiling, serum samples were analysed and quantified by liquid chromatography-mass spectrometry (LC-MS). Receiver-operating characteristic (ROC) curves were used to classify putative candidate biomarkers. MDD patients had significantly higher serum levels of glutamic acid, aspartic acid and glycine but lower levels of 3-Hydroxykynurenine; glutamic acid and phenylalanine levels also correlated with depression severity. Combining these four metabolites allowed for accurate discrimination of MDD patients and HCs, with 65.7% of depressed patients and 62.9% of HCs correctly classified. Glutamic acid, aspartic acid, glycine and 3-Hydroxykynurenine may serve as potential diagnostic biomarkers, whereas glutamic acid and phenylalanine may be markers for depression severity. To elucidate the association between these indicators and clinical features, it is necessary to conduct additional studies with larger sample sizes that involve a spectrum of depressive symptomatology.

A Phase II, Open-Label Clinical Trial of Intranasal Ketamine for Depression in Patients with Cancer Receiving Palliative Care (INKeD-PC Study)

Antidepressants require several weeks for the onset of action, a lag time that may exceed life expectancy in palliative care. Ketamine has demonstrated rapid antidepressant effects, but has been minimally studied in cancer and palliative care populations. Herein, the objective was to determine the feasibility, safety, tolerability and preliminary efficacy of intranasal racemic ketamine for major depressive disorder (MDD) in patients with advanced cancer. We conducted a single-arm, open-label phase II trial at the Princess Margaret Cancer Centre in Toronto, ON, Canada. Participants with advanced cancer with moderate to severe MDD received three flexible doses of intranasal (IN) ketamine (50−150 mg) over a one-week period. The primary efficacy outcome was an antidepressant response and remission rates as determined by the Montgomery−Åsberg Depression Rating Scale (MADRS) from baseline to the Day 8 primary endpoint. Twenty participants were enrolled in the trial, receiving at least one dose of IN ketamine, with fifteen participants receiving all three doses. The Day 8 antidepressant response (MADRS decreased by >50%) and remission (MADRS < 10 on Day 8) rates were high at 70% and 45%, respectively. Mean MADRS scores decreased significantly from baseline (mean MADRS of 31, standard deviation 7.6) to Day 8 (11 +/− 7.4) with an overall decrease of 20 points (p < 0.001). Antidepressant effects were partially sustained in the second week in the absence of additional ketamine doses, with a Day 14 mean MADRS score of 14 +/− 9.9. Common adverse effects included fatigue, dissociation, nausea, dysgeusia and headaches; almost all adverse effects were mild and transient, resolving within 2 h of each ketamine dose with one dropout related to adverse effects (negative dissociative episode). Given these promising findings, larger, controlled trials are merited.

Ketamine and esketamine in suicidal thoughts and behaviors: a systematic review

BACKGROUND

More than 2% of the general population experience suicidal ideas each year and a large number of them will attempt suicide. Evidence-based therapeutic options to manage suicidal crisis are currently limited.

OBJECTIVES

The aim of this study was to overview the findings on the use of ketamine and esketamine for the treatment of suicidal ideas and acts.

DESIGN

Systematic review.

DATA SOURCES AND METHODS

PubMed, article references, and Clinicaltrials.gov up to June 30, 2022. Meta-analyses published within the last 2 years were also reviewed.

RESULTS

We identified 12 randomized controlled trials with reduction of suicidal ideation as the primary objective and 14 trials as secondary objectives. Intravenous racemic ketamine was superior to control drugs (placebo or midazolam) within the first 72 h, in spite of large placebo effects. Adverse events were minor and transient. In contrast, intranasal esketamine did not differ from placebo in large-scale studies. Limitations, clinical considerations, and opportunities for future research include the following points: large placebo effects when studying suicidal ideation reduction; small concerns about blinding quality due to dissociative effects; no studies on the risk/prevention of suicidal acts and mortality; lack of studies beyond affective disorders; no studies in adolescents and older people; lack of knowledge of long-term side effects, notably liability for abuse; no robust predictive markers; limited understanding of the mechanisms of ketamine on suicidal ideas; need for improved assessment of suicidal ideation in clinical trials; need for studies in outpatient settings, emergency room, and liaison consultation; need for research on ketamine administration; limited knowledge on the positive and negative effects of concomitant treatments.

CONCLUSION

Overall, there is compelling evidence for a favorable short-term benefit-risk balance with intravenous racemic ketamine but not intranasal esketamine. The place of ketamine will have to be defined within a multimodal care strategy for suicidal patients. Caution remains necessary for clinical use, and pharmacovigilance will be essential.

The Glutamatergic System in Treatment-Resistant Depression and Comparative Effectiveness of Ketamine and Esketamine: Role of Inflammation?

The glutamatergic system is the primary excitatory pathway within the CNS and is responsible for cognition, memory, learning, emotion, and mood. Because of its significant importance in widespread nervous system function, it is tightly regulated through multiple mechanisms, such as glutamate recycling, microglial interactions, and inflammatory pathways. Imbalance within the glutamatergic system has been implicated in a wide range of pathological conditions including neurodegenerative conditions, neuromuscular conditions, and mood disorders including depression. Major depressive disorder (MDD) is the most common mood disorder worldwide, has a high prevalence rate, and afflicts approximately 280 million people. While there are numerous treatments for the disease, 30-40% of patients are unresponsive to treatment and deemed treatment resistant; approximately another third experience only partial improvement (World Health Organization, Depression fact sheet [Internet], 2020). Esketamine, the S-enantiomer of ketamine, was approved by the Food and Drug Administration for treatment-resistant depression (TRD) in 2019 and has offered new hope to patients. It is the first treatment targeting the glutamatergic system through a complex mechanism. Numerous studies have implicated imbalance in the glutamatergic system in depression and treatment resistance. Esketamine and ketamine principally work through inhibition of the NMDA receptor, though more recent studies have implicated numerous other mechanisms mediating the antidepressant efficacy of these agents. These mechanisms include increase in brain-derived neurotrophic factor (BDNF), activation of mammalian target of the rapamycin complex (mTORC), and reduction in inflammation. Esketamine and ketamine have been shown to decrease inflammation in numerous ways principally through reducing pro-inflammatory cytokines (e.g., TNF-α, IL-6) (Loix et al., Acta Anaesthesiol Belg 62(1):47-58, 2011; Chen et al., Psychiatry Res 269:207-11, 2018; Kopra et al., J Psychopharmacol 35(8):934-45, 2021). This anti-inflammatory effect has also been shown to be involved in the antidepressive properties of both ketamine and esketamine (Chen et al., Psychiatry Res 269:207-11, 2018; Kopra et al., J Psychopharmacol 35(8):934-45, 2021).

A unified model of ketamine's dissociative and psychedelic properties

Ketamine is an N-methyl-d-aspartate antagonist which is increasingly being researched and used as a treatment for depression. In low doses, it can cause a transitory modification in consciousness which was classically labelled as 'dissociation'. However, ketamine is also commonly classified as an atypical psychedelic and it has been recently reported that ego dissolution experiences during ketamine administration are associated with greater antidepressant response. Neuroimaging studies have highlighted several similarities between the effects of ketamine and those of serotonergic psychedelics in the brain; however, no unified account has been proposed for ketamine's multi-level effects - from molecular to network and psychological levels. Here, we propose that the fast, albeit transient, antidepressant effects observed after ketamine infusions are mainly driven by its acute modulation of reward circuits and sub-acute increase in neuroplasticity, while its dissociative and psychedelic properties are driven by dose- and context-dependent disruption of large-scale functional networks. Computationally, as nodes of the salience network (SN) represent high-level priors about the body ('minimal' self) and nodes of the default-mode network (DMN) represent the highest-level priors about narrative self-experience ('biographical' self), we propose that transitory SN desegregation and disintegration accounts for ketamine's 'dissociative' state, while transitory DMN desegregation and disintegration accounts for ketamine's 'psychedelic' state. In psychedelic-assisted psychotherapy, a relaxation of the highest-level beliefs with psychotherapeutic support may allow a revision of pathological self-representation models, for which neuroplasticity plays a permissive role. Our account provides a multi-level rationale for using the psychedelic properties of ketamine to increase its long-term benefits.

Effect of Subanesthetic Dose of Esketamine on Perioperative Neurocognitive Disorders in Elderly Undergoing Gastrointestinal Surgery: A Randomized Controlled Trial

Background

Perioperative neurocognitive disorders (PND), including delayed neurocognitive recovery (dNCR) and postoperative cognitive dysfunction (POCD), are common postoperative complications in elderly patients and adversely affect their prognosis. The study was designed to explore the effects of esketamine on postoperative cognitive function in elderly patients who underwent gastrointestinal surgery under general anesthesia and its potential mechanism.

Methods

Eighty-four patients aged 65 and above undergoing gastrointestinal surgery were randomly divided into 2 groups: the esketamine group (group S) and the control group (group C). Group S received intravenous sub-anesthetic doses of esketamine (0.15 mg/kg) 5 minutes before the initiation of surgery, while group C received the same volume of saline. A battery of neuropsychological tests was used to assess cognitive function before surgery, 7 days, and 3 months after surgery. The primary outcome was the incidence of dNCR at 7 days postoperatively and POCD at 3 months postoperatively in both groups. The secondary outcome measures included changes in the levels of serum interleukin-6 (IL-6) and calcium-binding protein β (S100β) before and 1 day after surgery.

Results

The incidence of dNCR in group S was lower than that of group C (18.15% vs 38.24% P=0.033). Contrarily, there was no difference in both groups regarding POCD 3 months postoperatively (6.06% vs 14.37% P=0.247). Plasma IL-6 and S100β levels were significantly elevated in both groups on postoperative day 1 (p<0.05), but esketamine pretreatment reduced these levels to some extent compared with group C (p<0.05).

Conclusion

Sub-anesthetic doses of esketamine might reduce the incidence of dNCR and improve early postoperative cognitive function in elderly patients undergoing gastrointestinal surgery, which might be related to the anti-neuroinflammation effects of esketamine.

The potential of ketamine for posttraumatic stress disorder: a review of clinical evidence

Posttraumatic stress disorder (PTSD) is a devastating condition, for which there are few pharmacological agents, often with a delayed onset of action and poor efficacy. Trauma-focused psychotherapies are further limited by few trained providers and low patient engagement. This frequently results in disease chronicity as well as psychiatric and medical comorbidity, with considerable negative impact on quality of life. As such, off-label interventions are commonly used for PTSD, particularly in chronic refractory cases. Ketamine, an N-methyl-D-aspartate (NDMA) receptor antagonist, has recently been indicated for major depression, exhibiting rapid and robust antidepressant effects. It also shows transdiagnostic potential for an array of psychiatric disorders. Here, we synthesize clinical evidence on ketamine in PTSD, spanning case reports, chart reviews, open-label studies, and randomized trials. Overall, there is high heterogeneity in clinical presentation and pharmacological approach, yet encouraging signals of therapeutic safety, efficacy, and durability. Avenues for future research are discussed.

Acute Effects of Intravenous Sub-Anesthetic Doses of Ketamine and Intranasal Inhaled Esketamine on Suicidal Ideation: A Systematic Review and Meta-Analysis

Purpose

Suicide is a major public health concern with currently no validated and efficacious treatments approved. Preliminary evidence suggests that intravenous ketamine has rapid and sustained antidepressant effects, making it a candidate with therapeutic potential for depressed patients at risk for suicide. We conducted a meta-analysis to evaluate the efficacy of ketamine and esketamine in reducing suicidal ideation (SI), as well as their respective onset and duration of action.

Data Sources

We searched PubMed, Embase, Ovid, Cochrane, and Web of Science databases for studies published from inception to September 29, 2022.

Study Eligibility Criteria

We conducted a systematic review of all parallel randomized controlled trials (RCTs) examining the effect and duration of ketamine or esketamine on SI. Our primary outcome measure was the Suicide Scale score, which was measured using the Scale for Suicidal Ideation (SSI), Beck Scale for Suicide Ideation (BSS), Beck Depression Inventory (BDI), or Modified Scale for Suicidal Ideation (MSSI). To obtain effect sizes (Cohen's d), we calculated the difference in Suicide Scale scores before and after administration in each group.

Results

Our study showed that intravenous sub-anesthetic doses of ketamine and intranasal inhaled esketamine had a significant anti-SI effect. Specifically, ketamine produced a large degree of anti-SI effect within the 4-6 hours (Cohen's d = 1.16, 95% CI: 0.50, 1.81) and a medium-large degree in the 24 hours (Cohen's d = 0.95, 95% CI: 0.48, 1.41). Esketamine, on the other hand, produced a small-medium degree of anti-SI effect within the 4-6 hours timeframe (Cohen's d = 0.26, 95% CI: 0.09, 0.44) and the 24 hours (Cohen's d = 0.30, 95% CI: 0.17, 0.47).

Conclusion

Intravenous sub-anesthetic doses of ketamine and intranasal inhaled esketamine could reduce SI within 4 hours and last for 24 hours.

Effects of the Different Doses of Esketamine on Postoperative Quality of Recovery in Patients Undergoing Modified Radical Mastectomy: A Randomized, Double-Blind, Controlled Trial

Purpose

This study aims to investigate the effects of the different doses of esketamine on postoperative quality of recovery in patients undergoing modified radical mastectomy.

Methods

Ninety-nine female patients were randomly allocated to three groups: the low-dose esketamine group (group E₁) (0.5 mg/kg loading, 2 µg/kg/h infusion), the high-dose esketamine group (group E₂) (0.5 mg/kg loading, 4 µg/kg/h infusion), the control group (group C) (received normal saline). The primary outcome was the quality of recovery-15 (QoR-15) scores on postoperative day 1 (POD1) and days 3 (POD3). The secondary outcomes were the sleep quality scores on POD1, bispectral index (BIS) value at 10, 30, and 60 min after operation, numeric rating scale (NRS) pain scores within 24 h after surgery, nausea, vomiting, drowsiness, nightmare, and intraoperative awareness.

Results

The total QoR-15 scores were higher in group E₁ and group E₂ than in group C on POD1 and POD3 (P<0.05). The sleep quality scores on POD1 and BIS value at 10, 30, and 60 min after operation were higher in group E₁ and group E₂ than in group C (P<0.05). The NRS pain scores at 2, 4 and 6 h after surgery in group E₁ and at 2, 4, 6, 12 and 24 h after surgery in group E₂ were lower than in group C (P<0.05). The NRS pain scores at 6, 12 and 24 h after surgery in group E₂ were lower than in group E₁ (P<0.05). The incidence of drowsiness was higher in group E₁ and group E₂ than in group C (P<0.05).

Conclusion

Esketamine infusion improved to some extent the quality of recovery on POD1 and POD3 in patients undergoing modified radical mastectomy, especially 4 µg/kg/h esketamine was better, but the BIS value and incidence of drowsiness were significantly increased.

Cost-effectiveness of esketamine nasal spray compared to intravenous ketamine for patients with treatment-resistant depression in the US utilizing clinical trial efficacy and real-world effectiveness estimates

OBJECTIVE

The aim of this study was to estimate the cost-effectiveness of esketamine nasal spray relative to intravenous ketamine for patients with treatment-resistant depression (TRD) in the US.

METHODS

We used a Markov model with a 1-month cycle length, and we estimated quality-adjusted life years (QALYs), costs (2020 USD), and incremental cost-effectiveness ratios (ICER) of esketamine relative to ketamine over a 3-year time horizon, from both the healthcare sector and patient perspectives. We ran the model using efficacy estimates from both clinical trial and real-world effectiveness (RWE) data. One-way and probabilistic sensitivity analyses (PSAs) were performed to evaluate the robustness of findings.

RESULTS

Over a 3-year time horizon, the use of esketamine yielded 1.98 QALYs (RWE/clinical trial efficacy), and the use of ketamine yielded 2.03 QALYs (clinical trial efficacy) or 1.99 QALYs (RWE). Esketamine was dominated by ketamine using the healthcare perspective. ICERs were above $150,000/QALY threshold with the patient perspective. Under the healthcare perspective, PSA showed there are no scenarios where esketamine was cost-effective compared to ketamine. With the patient's perspective, the probability that esketamine was cost-effective compared to ketamine was 0.0055 (clinical trial efficacy) and 0.35 (RWE).

LIMITATIONS

The data utilized for efficacy have limitations. The time horizon may fail to capture longer-term costs and benefits.

CONCLUSIONS

In this decision analytic model evaluating esketamine versus ketamine for TRD, we found esketamine unlikely to be cost-effective under a healthcare sector perspective. Under a patient perspective, esketamine had similar effectiveness and was less costly than ketamine due to insurance coverage.

Esketamine-A quick-acting novel antidepressant without the disadvantages of ketamine

Esketamine, which is an S-enantiomer of ketamine, is better than conventional antidepressants and even better than R-ketamine. This article discusses the mechanism of action of Esketamine, how different it is from other antidepressants, its side effect profile, indications for use, various routes of administration and the review of existing literature on Esketamine.

Association between peripheral biomarkers and clinical response to IV ketamine for unipolar treatment-resistant depression: An open label study

BACKGROUND

Major Depression is the leading cause of disability worldwide. A cohort of patients do not respond adequately to available antidepressants, leading to treatment-resistant depression (TRD). We evaluated the antidepressant efficacy of an acute intravenous ketamine treatment (0.5 mg/kg) for patients with unipolar TRD, and measured peripheral blood-based biomarkers associated with response to treatment.

METHODS

Fifteen adults diagnosed with TRD completed an open label study of ten infusions of subanesthetic ketamine over four weeks. Out of fifteen patients, blood was collected from eleven patients at three timepoints to analyze peripheral biomarkers in isolated plasma, including IL-6, IL-10, TNF-α, BDNF, and irisin. Irisin analysis was completed using an ELISA assay, and the remaining biomarkers were analyzed together simultaneously using a multiplex immunoassay.

RESULTS

Repeated ketamine infusions produced a significant decrease in total average depressive symptoms (MADRS) at all timepoints. Improvements in depressive symptoms were significant at one week, and continued to significantly decrease until two weeks, where it was maintained. Ketamine was generally well tolerated, and we observed improvements in functional impairment, anhedonia, and psychiatric symptoms, with no increases in manic symptoms. Levels of BDNF throughout treatment inversely correlated to decreases in MADRS scores, and higher levels of baseline BDNF predicted mood responses at one- and four weeks.

LIMITATIONS

The study was observational and uncontrolled, with a sample size of 15. Outpatients remained on their course of medications, unless they were pharmacological agents that have previously been identified to block ketamine's effects.

CONCLUSIONS

Ketamine may be an efficacious and safe pharmacological option for the acute treatment of patients suffering from severe TRD. BDNF has the potential to function as a prognostic biomarker for predicting response to ketamine treatments.

Does route of administration affect antidepressant efficacy of ketamine? A meta-analysis of double-blind randomized controlled trials comparing intravenous and intranasal administration

Intranasal (IN) and intravenous (IV) applications of ketamine have been proven effective for the treatment of depression, but direct comparative trials or meta-analyses on whether both differ in their antidepressant efficacy are lacking. We aimed to meta-analytically compare the short-term efficacy of a single dose of IV and IN ketamine in adult patients with major depressive disorder (MDD) and included double-blind, randomized controlled trials published until February 2022 in our analyses. The main outcome was a response 24 h after the administration of a single dose of ketamine. A random-effects model was used to calculate odds ratios and confidence intervals. Differences in efficacy between intranasal and intravenous application were statistically assessed by calculating a z-test. A total of eleven studies, comprising 1340 patients, were included. Results showed, that while both IN and IV ketamine were associated with increased response rates, efficacy did not differ significantly between these routes. Heterogeneity and funnel plot asymmetry was found in the intranasal sample only. The results of the present meta-analysis corroborate the efficacy of both IN and IV application of ketamine for the treatment of MDD but suggest no difference between both routes of administration. Accordingly, future large-scale trials as well as direct comparative trials are needed to further investigate this question.

Dose-dependent effects of esketamine on brain activity in awake mice: A BOLD phMRI study

Pharmacological magnetic resonance imaging (phMRI) is a noninvasive method used to evaluate neural circuitry involved in the behavioral effects of drugs like ketamine, independent of their specific biochemical mechanism. The study was designed to evaluate the immediate effect of esketamine, the S-isomer of (±) ketamine on brain activity in awake mice using blood oxygenation level dependent (BOLD) imaging. It was hypothesized the prefrontal cortex, hippocampus, and brain areas associated with reward and motivation would show a dose-dependent increase in brain activity. Mice were given vehicle, 1.0, 3.3, or 10 mg/kg esketamine I.P. and imaged for 10 min post-treatment. Data for each treatment were registered to a 3D MRI mouse brain atlas providing site-specific information on 134 different brain areas. There was a global change in brain activity for both positive and negative BOLD signal affecting over 50 brain areas. Many areas showed a dose-dependent decrease in positive BOLD signal, for example, cortex, hippocampus, and thalamus. The most common profile when comparing the three doses was a U-shape with the 3.3 dose having the lowest change in signal. At 1.0 mg/kg there was a significant increase in positive BOLD in forebrain areas and hippocampus. The anticipated dose-dependent increase in BOLD was not realized; instead, the lowest dose of 1.0 mg/kg had the greatest effect on brain activity. The prefrontal cortex and hippocampus were significantly activated corroborating previous imaging studies in humans and animals. The unexpected sensitivity to the 1.0 mg/kg dose of esketamine could be explained by imaging in fully awake mice without the confound of anesthesia and/or its greater affinity for the N-methyl-d-aspartate receptor (NMDAR) receptor than (±) ketamine.