Esketamine Nasal Spray Plus Oral Antidepressant in Patients With Treatment-Resistant Depression: Assessment of Long-Term Safety in a Phase 3, Open-Label Study (SUSTAIN-2)

Increasing the bioavailability of oral esketamine by a single dose of cobicistat: A case study

Background

Intranasal esketamine is an approved drug for treatment‐resistant depression (TRD); however, it is costly and may result in specific adverse effects. In this single case study, we explored if oral esketamine can be a suitable alternative.

Methods

In collaboration with a 39‐year‐old female with TRD, we compared plasma concentration curves of intranasal (84 mg) and oral (1, 2 and 4 mg/kg) esketamine. Because oral esketamine has a relatively low bioavailability, it results in a different ratio between esketamine and its primary metabolite noresketamine. To increase the bioavailability of oral esketamine, we co‐administered a single dose of the cytochrome P‐450 (CYP) 3A4 inhibitor cobicistat (150 mg).

Results

For all doses administered, oral esketamine resulted in lower esketamine but higher noresketamine peak plasma concentrations compared with intranasal treatment. Using oral esketamine it was not possible to generate a similar esketamine plasma concentration curve as with the intranasal treatment, except when combined with cobicistat (esketamine 2 mg/kg plus cobicistat 150 mg).

Conclusions

Our findings demonstrate that cobicistat effectively increases the bioavailability of oral esketamine. Further research is required in a larger population, especially to investigate the clinical benefit of cobicistat as a booster drug for oral esketamine.

Efficacy of ketamine versus esketamine in the treatment of perioperative depression: A review

Depression is a significant factor contributing to postoperative occurrences, and patients diagnosed with depression have a higher risk for postoperative complications. Studies on cardiovascular surgery extensively addresses this concern. Several studies report that people who undergo coronary artery bypass graft surgery have a 20% chance of developing postoperative depression. A retrospective analysis of medical records spanning 21 years, involving 817 patients, revealed that approximately 40% o individuals undergoing coronary artery bypass grafting (CABG) were at risk of perioperative depression. Patients endure prolonged suffering from illness because each attempt with standard antidepressants requires several weeks to be effective. In addition, multi-drug combination adjuvants or combination medication therapy may alleviate symptoms for some individuals, but they also increase the risk of side effects. Conventional antidepressants primarily modulate the monoamine system, whereas different therapies target the serotonin, norepinephrine, and dopamine systems. Esketamine is a fast-acting antidepressant with high efficacy. Esketamine is the S-enantiomer of ketamine, a derivative of phencyclidine developed in 1956. Esketamine exerts its effect by targeting the glutaminergic system the glutaminergic system. In this paper, we discuss the current depression treatment strategies with a focus on the pharmacology and mechanism of action of esketamine. In addition, studies reporting use of esketamine to treat perioperative depressive symptoms are reviwed, and the potential future applications of the drug are presented.

Facts and myths about use of esketamine for treatment-resistant depression: a narrative clinical review

Introduction and aims

Treatment-resistant depression (TRD) occurs when at least two different antidepressants, taken at the right dosage, for adequate period of time and with continuity, fail to give positive clinical effects. Esketamine, the S-enantiomer of ketamine, was recently approved for TRD treatment from U.S. Food and Drug Administration and European Medicine Agency. Despite proved clinical efficacy, many misconceptions by clinicians and patients accompany this medication. We aimed to review the most common "false myths" regarding TRD and esketemine, counterarguing with evidence-based facts.

Methods

The keywords "esketamine", "treatment resistance depression", "depression", "myth", "mythology", "pharmacological treatment", and "misunderstanding" were entered in the main databases and combined through Boolean operators.

Results

Misconceptions regarding the TRD prevalence, clinical features and predictors have been found. With respect of esketamine, criteria to start treatment, dissociative symptoms, potential addiction and aspects of administration and monitoring, were found to be affected by false beliefs by clinicians and patients.

Discussion and conclusion

TRD represents a challenging condition, requiring precise diagnosis in order to achieve patient's full recovery. Esketamine has been proved as an effective medication to treat TRD, although it requires precautions. Evidence can inform clinical practice, in order to offer this innovative treatment to all patients with TRD.

Guidelines for ketamine use in clinical psychiatry practice

In this editorial, we emphasise the efficacy and challenges of using ketamine in treatment-resistant depression. We highlight the need for comprehensive evidence-based guidelines to manage the use of both licensed and off-licence ketamine formulations and discuss recent efforts by Beaglehole et al to develop ketamine guidelines in New Zealand. We finally advocate for national registries to monitor ketamine therapy, ensuring its responsible and effective use in the management of depression.

Cognitive outcomes from the randomised, active-controlled Ketamine for Adult Depression Study (KADS)

BACKGROUND

Due to its rapid antidepressant effect, ketamine has recently been clinically translated for people with treatment-resistant depression. However, its cognitive profile remains unclear, particularly with repeated and higher doses. In the present study, we report the cognitive results from a recent large multicentre randomised controlled trial, the Ketamine for Adult Depression Study (KADS).

METHODS

In this randomised, double-blind, active-controlled, parallel group, multicentre phase 3 trial study we investigated potential cognitive changes following repeated treatment of subcutaneous racemic ketamine compared to an active comparator, midazolam, over 4 weeks, which involved two cohorts; Cohort 1 involved a fixed dose treatment protocol (0.5 mg/kg ketamine), Cohort 2 involved a dose escalation protocol (0.5-0.9 mg/kg) based on mood outcomes. Participants with treatment-resistant Major Depressive Disorder (MDD) were recruited from 7 mood disorder centres and were randomly assigned to receive ketamine (Cohort 1 n = 33; Cohort 2 n = 53) or midazolam (Cohort 1 n = 35; Cohort 2 n = 53) in a 1:1 ratio. Cognitive measurements were assessed at baseline and at the end of randomised treatment.

RESULTS

Results showed that in Cohort 1, there were no differences between ketamine and midazolam in cognitive outcomes. For Cohort 2, there was similarly no difference between conditions for cognitive outcomes.

LIMITATIONS

The study included two Cohorts with different dosing regimes.

CONCLUSIONS

The findings support the cognitive safety of repeated fixed and escalating doses at least in the short-term in people with treatment resistant MDD.

Depression with comorbid borderline personality disorder - could ketamine be a treatment catalyst?

Borderline personality disorder (BPD) is diagnosed in 10-30% of patients with major depressive disorder (MDD), and the frequency of MDD among individuals with BPD reaches over 80%. The comorbidity of MDD and BPD is associated with more severe depressive symptoms and functional impairment, higher risk of treatment resistance and increased suicidality. The effectiveness of ketamine usage in treatment resistant depression (TRD) has been demonstrated in numerous studies. In most of these studies, individuals with BPD were not excluded, thus given the high co-occurrence of these disorders, it is possible that the beneficial effects of ketamine also extend to the subpopulation with comorbid TRD and BPD. However, no protocols were developed that would account for comorbidity. Moreover, psychotherapeutic interventions, which may be crucial for achieving a lasting therapeutic effect in TRD and BPD comorbidity, were not included. In the article, we discuss the results of a small number of existing studies and case reports on the use of ketamine in depressive disorders with comorbid BPD. We elucidate how, at the molecular and brain network levels, ketamine can impact the neurobiology and symptoms of BPD. Furthermore, we explore whether ketamine-induced neuroplasticity, augmented by psychotherapy, could be of use in alleviating core BPD-related symptoms such as emotional dysregulation, self-identity disturbances and self-harming behaviors. We also discuss the potential of ketamine-assisted psychotherapy (KAP) in BPD treatment. As there is no standard approach to the application of ketamine or KAP in individuals with comorbid TRD and BPD, we consider further research in the field as imperative. The priorities should include development of dedicated protocols, distinguishing subpopulations that may benefit most from such treatment and investigating factors that may influence its effectiveness and safety.

Perspectives in treatment-resistant depression: esketamine and electroconvulsive therapy

Modern electroconvulsive therapy (ECT) and the approval of nasal esketamine for clinical use have significantly improved the approach to treatment-resistant depression (TRD), which is defined as non-response to at least two different courses of antidepressants with verified adherence to treatment, adequate dosage, and duration of treatment. The goal of this literature review is to present the newest evidence regarding efficacy and safety. Furthermore, we aim to provide an overview of future perspectives in this field of research, for example, regarding structural and molecular effects. Both treatment methods will be critically evaluated for their individual advantages, disadvantages, and response rates. Firstly, we will discuss the well-established method of ECT and its different treatment modalities. Secondly, we will discuss the properties of ketamine, the discovery of its antidepressive effects and the route to clinical approval of the esketamine nasal spray. We will comment on research settings which have evaluated intravenous ketamine against ECT. The decision-making process between esketamine nasal spray or ECT should include the assessment of contraindications, age, severity of disease, presence of psychotic symptoms, patient preference and treatment accessibility. We conclude that both treatment options are highly effective in TRD. If both are indicated, pragmatically esketamine will be chosen before ECT; however, ECT studies in ketamine non-responders are missing.

The efficacy of nasal administration of esketamine in patients having moderate-to-severe pain after preoperative CT-guided needle localization: a randomized, double-blind, placebo-controlled trial

Background

Whether nasal administration of esketamine can provide effective analgesia is unclear in patients with acute pain after preoperative CT-guided needle localization.

Methods

In this double-blind, randomized, placebo-controlled trial, patients were assigned to receive either nasal administration of esketamine (0.3 mg/kg or 0.5 mg/kg) or saline (identical in appearance to esketamine) when they had visual analog scale (VAS) pain scores >3/10 during deep breathing after preoperative CT-guided needle localization. The primary outcome was the percentage of patients with satisfactory pain relief, which was defined as VAS pain scores ≤3/10 measured 15 min after intranasal of esketamine or saline. Secondary outcomes included VAS measured following esketamine or saline, the incidence and cumulative dose of rescue hydromorphone use, and related adverse events.

Results

A total of 90 patients were included in the final analysis. Following intranasal treatment, the percentage of patients with satisfactory pain relief was 16.7% (5/30) in the saline group, 56.7% (17/30) in the 0.3 mg/kg esketamine group, and 53.3% (16/30) in the 0.5 mg/kg esketamine group (p = 0.002). The median VAS during deep breathing was less after the intranasal administration of esketamine {median (IQR), 3 (3, 5) in 0.3 mg/kg or 0.5 mg/kg esketamine compared to the saline group [5 (4, 6)], p = 0.009}. The incidence of rescue hydromorphone use was detected less in the esketamine group compared to the saline group (43.3% in the 0.3 mg/kg esketamine group, 36.7% in the 0.5 mg/kg esketamine group, and 73.3% in the saline group, p = 0.010). The adverse events were similar among the three groups (p > 0.05).

Conclusion

Intranasal administration of esketamine is easier and more effective in alleviating acute pain in patients after preoperative CT-guided needle localization without significant adverse effects.

The rapid antidepressant effectiveness of repeated dose of intravenous ketamine and intranasal esketamine: A post-hoc analysis of pooled real-world data

INTRODUCTION

Intravenous ketamine (KET-IV) and intranasal esketamine (ESK-NS) are effective in the acute treatment of Treatment-Resistant Depression (TRD). Studies comparing KET-IV and ESK-NS concerning their action, safety, and tolerability are currently lacking.

MATERIALS AND METHODS

We combined patients' data from two unipolar TRD cohorts that received KET-IV (n = 171) at the Canadian Rapid Treatment Center of Excellence in Toronto, Canada, or ESK-NS (n = 140) at several TRD clinics in Italy. The Quick Inventory for Depression Symptomatology-Self-Report-16/QIDS-SR16 in the KET-IV group and Montgomery-Åsberg Depression Rating Scale/MADRS in the ESK-NS group measured depressive symptoms at baseline (T0) and after the acute treatment phase (T1) (i.e., four infusions of KET-IV and eight administrations of ESK-NS). As different scales were used, the primary outcome was to compare the improvement in depression severity in the two cohorts by measuring effect sizes, response and remission rates. Finally, we compare side effects and discontinuation rates.

RESULTS

At T1, KET-IV and ESK-NS significantly reduced depressive symptoms (respectively: QIDS-SR16 mean reduction = 5.65, p < 0.001; MADRS mean reduction = 11.41, p = 0.025). KET-IV showed larger effect sizes compared to ESK-NS (1.666 vs. 1.244). KET-IV had higher response rates (36 % vs. 25 %; p = 0.042) but not superior remission rates (13 % vs. 12 %; p = 0.845) than ESK-NS at T1. Despite more reported side effects, KET-IV did not cause more discontinuations for adverse events (4.6 % vs. 2.12 %; p = 0.228) than ESK-NS.

CONCLUSION

KET-IV showed a higher short-term antidepressant effect, whereas ESK-NS exhibited lower side effects. Both were generally well tolerated. Future head-to-head studies should consider the long-term efficacy of these treatments.

Recent Advances in the Treatment of Treatment-Resistant Depression: A Narrative Review of Literature Published from 2018 to 2023

PURPOSE OF REVIEW

We review recent advances in the treatment of treatment-resistant depression (TRD), a disorder with very limited treatment options until recently. We examine advances in psychotherapeutic, psychopharmacologic, and interventional psychiatry approaches to treatment of TRD. We also highlight various definitions of TRD in recent scientific literature.

RECENT FINDINGS

Recent evidence suggests some forms of psychotherapy can be effective as adjunctive treatments for TRD, but not as monotherapies alone. Little recent evidence supports the use of adjunctive non-antidepressant pharmacotherapies such as buprenorphine and antipsychotics for the treatment of TRD; side effects and increased medication discontinuation rates may outweigh the benefits of these adjunctive pharmacotherapies. Finally, a wealth of recent evidence supports the use of interventional approaches such as electroconvulsive therapy, ketamine/esketamine, and transcranial magnetic stimulation for TRD. Recent advances in our understanding of how to treat TRD have largely expanded our knowledge of best practices in, and efficacy of, interventional psychiatric approaches. Recent research has used a variety of TRD definitions for study inclusion criteria; research on TRD should adhere to inclusion criteria based on internationally defined guidelines for more meaningfully generalizable results.

Patterns of ketamine use among people with substance use disorder in France: Multisource analysis of the data from the French Addictovigilance Network

BACKGROUND

Due to its psychoactive effects, ketamine has become a drug used for non-medical purpose.

OBJECTIVES

To assess the latest trends in ketamine use among people with substance use disorder and to characterize its clinical complications using complementary health data sources of the French Addictovigilance Network.

METHODS

First, we extracted all reports involving ketamine from 2012 to 2021 from the database of the OPPIDUM program (i.e., a multicentric program conducted in collaboration with hundreds of substance abuse treatment facilities that collects data on drugs used by subjects with substance use disorders). We described the reports globally and the changes from 2012 to 2021. Second, we extracted all cases involving ketamine from July 2020 to December 2022 from the French National Pharmacovigilance Database (BNPV). We identified the cases related to ketamine use among people with substance use disorder and described them.

RESULTS

There was a 2.5-fold increase in the number of ketamine users with substance use disorder in the OPPIDUM program, from 35 (0.7%) subjects in 2012 to 89 (1.7%) subjects in 2021. There was an increase in the proportion of subjects who were daily users, had distress upon discontinuation, and presented addiction. There were 238 cases related to ketamine use among people with substance use disorder in the French National Pharmacovigilance Database from July 2020 to December 2022. Among them, 94 (39.5%) cases involved ketamine use disorder, 20 (8.4%) cases involved urinary tract and kidney symptoms, and 13 (5.5%) cases involved hepatobiliary symptoms.

CONCLUSION

The trend observed over 10 years reflects the growth in ketamine use among people with substance use disorder, although it does not allow to estimate the rates of non-medical use of ketamine in the general population. Ketamine-induced uropathy and cholangiopathy are reported in ketamine users with substance use disorder, especially in case of repeated and/or prolonged use of high doses.

Combination of Acute and Maintenance Esketamine Treatment With Adjunctive Long-Term Vagus Nerve Stimulation in Difficult-to-Treat Depression

INTRODUCTION

The antidepressant effect of N-methyl-D-aspartate antagonists is often short lasting, raising the question of the best maintenance strategy, which has remained unanswered. Vagus nerve stimulation (VNS) as a treatment option for refractory and chronic major depression was shown to reduce the need for maintenance treatment sessions in patients receiving electroconvulsive therapy. To our knowledge, there are no published data on the combination of VNS and esketamine in the literature.

MATERIALS AND METHODS

This is a naturalistic prospective and retrospective observational study in patients treated with long-term VNS owing to difficult-to-treat depression. These patients also have received esketamine maintenance sessions in addition to short-term treatment. We have investigated the need for maintenance esketamine sessions per month after VNS implantation (number of sessions/number of months between visits), the change in depression severity (mean Montgomery-Asberg Depression Rating Scale [MADRS] score), and the number of hospitalizations per month (number of hospitalizations/number of postoperative observation months). Follow-up visits have been scheduled every three months after VNS implantation (follow-up period 12-24 months, mean 17).

RESULTS

All patients (n = 8, mean age 53.1 years) had severe difficult-to-treat depression (DTD) (mean MADRS at baseline 30.9). Mean number of hospitalizations per month decreased from 0.17 to 0.11 after VNS implantation (p = 0.041, T = 2.030, df = 7). Mean MADRS at 12 months was 18.3 (40.8% MADRS reduction, p = 0.008, T = 3.146, df = 7). Six of eight patients were offered maintenance esketamine treatment. Mean number of esketamine treatment sessions per month and case decreased from 2.3 at the six-month visit to 0.8 at 12 months (p = 0.076, T = 1,690, df = 5) after VNS implantation. Termination of maintenance esketamine was possible in four cases after a mean of 11.5 months.

CONCLUSIONS

Combination of esketamine and VNS was effective in patients with DTD to relieve disease severity and reduce hospitalizations. The need for esketamine treatment sessions decreased after 6 months of VNS. No safety concerns arose in this study regarding the combination treatment.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT03320304.

The mechanistic basis for the rapid antidepressant-like effects of ketamine: From neural circuits to molecular pathways

Conventional antidepressants that target monoaminergic receptors require several weeks to be efficacious. This lag represents a significant problem in the currently available treatments for serious depression. Ketamine, acting as an N-methyl-d-aspartate receptor antagonist, was shown to have rapid antidepressant-like effects, marking a significant advancement in the study of mood disorders. However, serious side effects and adverse reactions limit its clinical use. Considering the limitations of ketamine, it is crucial to further define the network targets of ketamine. The rapid action of ketamine an as antidepressant is thought to be mediated by the glutamate system. It is believed that synaptic plasticity is essential for the rapid effects of ketamine as an antidepressant. Other mechanisms include the involvement of the γ-aminobutyric acidergic (GABAergic), 5-HTergic systems, and recent studies have linked astrocytes to ketamine's rapid antidepressant-like effects. The interactions between these systems exert a synergistic rapid antidepressant effect through neural circuits and molecular mechanisms. Here, we discuss the neural circuits and molecular mechanisms underlying the action of ketamine. This work will help explain how molecular and neural targets are responsible for the effects of rapidly acting antidepressants and will aid in the discovery of new therapeutic approaches for major depressive disorder.

Impact of Adjunctive VNS on Drug Load, Depression Severity, and Number of Neuromodulatory Maintenance Treatments

Vagus nerve stimulation (VNS) is a long-term adjunctive treatment option in patients with difficult-to-treat depression (DTD). A total of n = 20 patients (mean age 52.6 years) were included in the multicenter, prospective, observational, naturalistic RESTORE-LIFE study and were treated with adjunctive VNS as an add-on to treatment as usual. Exploratory and secondary outcome parameters from a single center were investigated for this present analysis. The overall mean drug load slightly decreased from 4.5 at baseline to 4.4 at 12 months (Z = -0.534, p = 0.594). The drug load was lower in previous electroconvulsive therapy (ECT) responders than in non-responders. There was a reduction in the mean number of hospitalizations per month after VNS implantation (Z = 1.975, p = 0.048) and a significant decrease in the mean Montgomery Åsberg Depression Rating Scale (MADRS) score from 27.3 at baseline to 15.3 at 12 months (T = 4.230, degree of freedom (df) = 19, p = 0.001). A history of ECT response at baseline was associated with greater improvement in the MADRS score after 12 months of VNS (F = 8.171, p = 0.013). The number of neuromodulatory maintenance treatments decreased during the follow-up period. In summary, there was an alleviation in the burden of illness among DTD patients treated with VNS.

Exploring Esketamine's Therapeutic Outcomes as an FDA-Designated Breakthrough for Treatment-Resistant Depression and Major Depressive Disorder With Suicidal Intent: A Narrative Review

The expansive spectrum of major depressive disorder (MDD) continues to pose challenges for psychiatrists to treat effectively. Oral antidepressant (OAD) medications that alter monoamine neurotransmitters, mainly selective serotonin reuptake inhibitors (SSRIs) and selective norepinephrine reuptake inhibitors (SNRIs), have been the mainstay of therapy for decades. Although these drugs have been largely beneficial, a considerable subset of patients do not respond adequately to multiple conventional therapies administered for an appropriate length of time, leading to a diagnosis of treatment-resistant depression (TRD). Ketamine, a non-monoaminergic drug, has long been known for its beneficial effects on TRD when given intravenously (IV). Between 2019 and 2020, an intranasal formulation of the S (+) enantiomer of racemic ketamine, esketamine (ESK), was granted "breakthrough designation" by the FDA and approved for the indications of TRD and MDD patients exhibiting acute suicidal intent. The objective of this narrative review was to review the academic literature and collect clinical evidence that may corroborate intranasal ESK's effectiveness for its approved indications while addressing its safety and tolerability profile, adverse effects, and impact on cognition. An overview of the drug's origins, pharmacology, and standard treatment regimen are provided. The outcomes from double-blinded randomized control trials (DB-RCTs) of ESK are outlined to demonstrate the efficacy and safety data leading to its FDA approval, along with its long-term post-market safety outcomes. Comparative trials between ESK and ketamine are then evaluated to highlight ESK's consideration as a more practical alternative to ketamine in common clinical practice. The authors further discuss currently approved and developing therapies for TRD, propose future research directions, and identify the inherent limitations of the review and further research. To conduct the research required, three digital databases (PubMed, Medline, and ClinicalTrials.gov) were queried to search for key terms, including ketamine, esketamine, treatment-resistant depression, and biomarkers, using automation tools along with selective search engine results. After streamlining the results by title and abstract and removing duplicates, a total of 37 results were chosen, of which 18 are clinical trials. A reduction in the Montgomery-Asberg Depression Rating Scale (MADRS) score was the primary efficacy endpoint for most of these clinical trials. In conclusion, intranasal ESK, when used as an adjunct to market OADs, shows greater efficacy in treating TRD and MDD with suicidal intent compared to OADs and placebo alone and provides a more suitable alternative to IV ketamine. It is important to note that further research is required to fully understand the novel mechanism of action of ESK, as well as the establishment of a consensus definition of TRD, which may facilitate better detection and treatment protocols. More focused quantitative and qualitative ESK studies are needed, as well as those pertaining to its use in patients with co-existing mental illnesses.

A systematic review of the incidence of medical serious adverse events in sub-anesthetic ketamine treatment of psychiatric disorders

BACKGROUND

Limited published data exists that collates serious adverse outcomes involving ketamine as a psychiatric intervention. This systematic review assesses the reported incidence of medical serious adverse events (MSAEs), including but not limited to cardiovascular events, in patients receiving sub-anesthetic doses of ketamine for psychiatric disorders to guide practitioners during treatment planning, risk-benefit analyses, and the informed consent process.

METHODS

Pubmed database was searched for clinical trials of sub-anesthetic ketamine for psychiatric disorders in non-pregnant adult patients. Of the 2275 articles identified, 93 met inclusion criteria, over half of which were published in 2017 or later. Only studies that reported adverse events were included, and the incidence of MSAEs was calculated.

RESULTS

Of the 3756 participants who received at least one sub-anesthetic dose of ketamine, four participants experienced a MSAE, resulting in an incidence of approximately 0.1 % of individuals. The four MSAEs resolved without reported sequelae. Eighty-three percent of studies reported screening for medical illness and exclusion of high-risk patients. There were no serious cardiac adverse events or deaths observed in any participants; however, most trials' study designs excluded those with high cardiovascular complication risk.

LIMITATIONS

Most studies were small, underpowered for detecting rare MSAEs, at potential high-risk of bias of non-report of MSAEs, and limited mostly to intranasal and intravenous routes.

CONCLUSIONS

Findings suggest that with basic medical screening there is a very low incidence of MSAEs including adverse cardiac or cerebrovascular events in individuals receiving sub-anesthetic ketamine for psychiatric disorders.

Ketamine cystitis following ketamine therapy for treatment-resistant depression - case report

BACKGROUND

Ketamine is a novel and exciting putative antidepressant medication for patients with treatment-resistant depression. A complication commonly seen in frequent and heavy recreational use of ketamine is ulcerative cystitis, which presents with lower urinary tract symptoms (LUTS) and upper renal tract damage and can be seen in over 25% of regular users. Although Ketamine-induced cystitis (KIC) is a recognised complication in recreational use of ketamine, its occurrence in therapeutic use of ketamine in depression has so far not been reported. The exact pathogenesis of KIC is currently unknown, making treatment and prevention advice much more difficult. Early diagnosis of KIC and immediate cessation of ketamine has been shown to improve adverse urinary tract symptoms and prevent further damage.

CASE PRESENTATION

We present a case of a 28-year-old female who was started on ketamine treatment for depression, and who then developed symptoms of KIC, which was confirmed by urine microscopy, culture and analysis.

CONCLUSIONS

To our knowledge, this is the first reported case of KIC in a patient receiving treatment-dose ketamine as part of their antidepressant therapy.

The why, when, where, how, and so what of so-called rapidly acting antidepressants

Developing antidepressants that are not only more effective but are rapidly acting is the Holy Grail for psychiatry. We review multiple issues that arise in determining rapid responses in antidepressant trials. The current status of purportedly rapid acting agents is first reviewed. Then, a number of key questions/issues are addressed: Is there a unifying definition for rapid response across studies? Should rapid response criteria be based on required measurable effects on overall improvement? On specific symptoms such as psychomotor retardation, depressed mood, or anhedonia? In associated symptoms such as anxiety or insomnia? When should onset be considered rapid-by Day 3? Day7? Day 14? If there is a rapid response, for how long should the effects be maintained? Is maintenance of effect dependent on continuing the medication? Is rapid response associated with specific mechanisms of action? Do the mechanisms of action suggest possible risk for drug abuse? How important is rapid response really in an often chronic or recurrent depressive disorder? In which types of patients could rapid response be particularly important? What are the study design issues that need to be considered for assessing rapid response, including: selection of specific types of depressed patients, multiple doses of drug studied, designation of primary and secondary outcome measures, specific time points at which to determine efficacy, requirements for demonstrating durability, etc. A framework for approaching this complex area is developed for both researchers and clinicians.

The Efficacy and Safety of Intranasal Formulations of Ketamine and Esketamine for the Treatment of Major Depressive Disorder: A Systematic Review

Ketamine and its enantiomers represent an innovative glutamatergic agent as a treatment for individuals with treatment-resistant depression (TRD) and major depressive disorder (MDD) with suicidal ideation and behavior. Intranasal (IN) formulations could allow for quick onset of action on depressive symptoms as well as a reduction in side effects by bypassing the blood-brain barrier compared with administration via the intravenous route. The aim of this review was to provide an up-to-date analysis of the data on the efficacy and safety of IN ketamine and IN esketamine for the treatment of MDD. A systematic review following PRISMA guidelines was conducted. Databases (PubMed, Embase, MEDLINE, PsycINFO, and Google Scholar) were searched to capture articles about IN ketamine or IN esketamine for MDD. This systematic review highlighted the interest in IN routes of ketamine and esketamine for MDD patients with TRD or active suicidal ideation. They provide a rapid onset of antidepressant action within the first hours after administration. Nevertheless, the evidence of efficacy is stronger for IN esketamine than for IN ketamine in MDD patients. The safety profile appears to be acceptable for IN esketamine but requires further studies, and a more accurate IN delivery device is required for ketamine.

Short-term ketamine use in bipolar depression: a review of the evidence for short-term treatment management

Bipolar depression constitutes a major problem in psychiatry. It correlates with high suicidality, treatment resistance, chronicity, and poor quality of life. Registered treatment for bipolar depression is limited and insufficient. There is an urgent need for implementing new therapeutic strategies. Intranasal ketamine's enantiomer-esketamine is a novel rapid-acting antidepressant with proven efficacy in treatment-resistant depression. Research on bipolar depression, although not as comprehensive, indicates that it may be a viable and safe substitute with minimal risk for mood polarity changes. Reports suggest that ketamine treatment in bipolar depression may reduce suicidal tendencies, decrease anhedonia, and alleviate anxiety. Ketamine's mood-stabilizing properties are also hypothesized. In this narrative review, we focus on ketamine use as an add-on to standard medication for the acute treatment of bipolar depression.

Early effects predict trajectories of response to esketamine in treatment-resistant depression

BACKGROUND

The efficacy of esketamine in treatment-resistant depression (TRD) has been confirmed. However, its administration is expensive and restrictive, with limited knowledge on how long the treatment should be continued. Predicting the treatment outcome would benefit patients and alleviate the global treatment cost. We aimed to define distinct trajectories of treatment response and assess their predictability.

METHODS

In this longitudinal study, two independent samples of patients with unipolar or bipolar TRD were treated with esketamine in real-world settings. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) before each esketamine administration. Latent class analyses were used to define trajectories of response.

RESULTS

In the original sample (N = 50), we identified two classes whose trajectories depicted response and non-response, respectively. The model was validated in the confirmatory sample (N = 55). Class membership was influenced by a few baseline characteristics such as concomitant benzodiazepine medication, number of depressive episodes or polarity. On the other hand, after only two esketamine administrations, the MADRS score predicted the 90-day trajectory of response with an accuracy of 80 %.

LIMITATIONS

This observational study is not placebo-controlled. Therefore, its results and their generalizability need to be confirmed in experimental settings.

CONCLUSIONS

After the first administrations of esketamine, the MADRS score has a good capacity to predict the most plausible trajectory of response. While thresholds and their predictive values need to be confirmed, this finding suggests that clinicians could base on MADRS scores their decision to discontinue treatment because of poor remaining chances of treatment response.

Investigating the Effectiveness and Tolerability of Intranasal Esketamine Among Older Adults With Treatment-Resistant Depression (TRD): A Post-hoc Analysis from the REAL-ESK Study Group

INTRODUCTION

Treatment-resistant depression (TRD) is a serious and debilitating psychiatric disorder that frequently affects older patients. Esketamine nasal spray (ESK-NS) has recently been approved as a treatment for TRD, with multiple studies establishing its efficacy and tolerability. However, the real-world effectiveness, tolerability, and safety of this treatment in older adults is still unclear.

OBJECTIVES

To evaluate the efficacy and tolerability of ESK-NS in older subjects with TRD.

METHODS

This is a post-hoc analysis of the REAL-ESK study, a multicenter, retrospective, observational study. Participants here selected were 65 years or older at baseline. The Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A) were used to assess depressive and anxiety symptoms, respectively. Data were collected at three-time points: baseline, 1 month after the start of treatment (T1), and 3 months after treatment (T2).

RESULTS

The sample included older adults with TRD (n = 30). MADRS and HAM-A values decreased significantly at T1 (T0 versus T1: pholm <0.001, Cohen's d = 0.840) and T2 follow-ups (T0 versus T2: pholm <0.001, Cohen's d = 1.419). At T2, 53.3% of subjects were responders (MADRS score reduced ≥50%), while 33.33% were in remission (MADRS<10). ESK-NS-related adverse effects were in order of frequency dizziness (50%), followed by dissociation (33.3%), sedation (30%), and hypertension (13.33%). Six out of 30 participants (20%) discontinued treatment.

CONCLUSIONS

Our findings provide preliminary evidence of ESK-NS effectiveness in older adults with TRD, a highly debilitating depressive presentation. Furthermore, we observe high levels of treatment-emergent adverse events, which, in the majority of instances, did not require treatment suspension.

What clinicians need to know about intranasal esketamine for treatment-resistant depression?

OBJECTIVE

To review the usefulness of esketamine for treatment-resistant depression.

METHOD

Pivotal trials of intranasal esketamine in treatment-resistant depression were synthesized as a narrative review.

RESULTS

Esketamine is postulated to act through antagonism of N-methyl-D-aspartate (NMDA) glutamate receptors, but opioidergic effects may also be involved. Unlike intravenous ketamine, esketamine is given intranasally (under clinical observation), usually in addition to an oral antidepressant. Trials compared esketamine plus antidepressant versus placebo plus antidepressant. At 4 weeks, remission was 37% higher with esketamine/antidepressant than placebo/antidepressant. Speed of response and improvement in suicidality were comparable. In stable remitters on esketamine/antidepressant, 45% relapsed when esketamine was withdrawn over the following 6 months (whereas 25% relapsed on esketamine/antidepressant). Response appears less likely in patients with multiple antidepressant failures. Adverse effects include dissociation, dizziness, nausea, sedation, and headache but no psychosis. Hypertension affected 13%, especially older patients. Dose frequency is twice-weekly for 4 weeks, then weekly/fortnightly thereafter. No abuse has been reported. Unsubsidised cost may be beyond the reach of many Australians.

CONCLUSION

Intranasal esketamine plus antidepressant has been approved by regulators as moderately effective and acceptably tolerable for treatment-resistant depression. Cost is a drawback. Use often needs to be long-term and vigilance for abuse is essential.

Efficacy and safety of a 4-week course of repeated subcutaneous ketamine injections for treatment-resistant depression (KADS study): randomised double-blind active-controlled trial

BACKGROUND

Prior trials suggest that intravenous racemic ketamine is a highly effective for treatment-resistant depression (TRD), but phase 3 trials of racemic ketamine are needed.

AIMS

To assess the acute efficacy and safety of a 4-week course of subcutaneous racemic ketamine in participants with TRD. Trial registration: ACTRN12616001096448 at www.anzctr.org.au.

METHOD

This phase 3, double-blind, randomised, active-controlled multicentre trial was conducted at seven mood disorders centres in Australia and New Zealand. Participants received twice-weekly subcutaneous racemic ketamine or midazolam for 4 weeks. Initially, the trial tested fixed-dose ketamine 0.5 mg/kg versus midazolam 0.025 mg/kg (cohort 1). Dosing was revised, after a Data Safety Monitoring Board recommendation, to flexible-dose ketamine 0.5-0.9 mg/kg or midazolam 0.025-0.045 mg/kg, with response-guided dosing increments (cohort 2). The primary outcome was remission (Montgomery-Åsberg Rating Scale for Depression score ≤10) at the end of week 4.

RESULTS

The final analysis (those who received at least one treatment) comprised 68 in cohort 1 (fixed-dose), 106 in cohort 2 (flexible-dose). Ketamine was more efficacious than midazolam in cohort 2 (remission rate 19.6% v. 2.0%; OR = 12.1, 95% CI 2.1-69.2, P = 0.005), but not different in cohort 1 (remission rate 6.3% v. 8.8%; OR = 1.3, 95% CI 0.2-8.2, P = 0.76). Ketamine was well tolerated. Acute adverse effects (psychotomimetic, blood pressure increases) resolved within 2 h.

CONCLUSIONS

Adequately dosed subcutaneous racemic ketamine was efficacious and safe in treating TRD over a 4-week treatment period. The subcutaneous route is practical and feasible.

Cognitive behavioral therapy following esketamine for major depression and suicidal ideation for relapse prevention: The CBT-ENDURE randomized clinical trial study protocol

In 2020, esketamine received a supplemental indication as a therapy for major depression with suicidal ideation (MDSI), based on protocols enrolling hospitalized patients. Given the high risk of suicide following hospital discharge and the high relapse rates following discontinuation of esketamine, the optimal long-term treatment approach remains unclear. Cognitive behavioral therapy (CBT) is highly effective in relapse prevention and has been shown to prevent suicide attempts in high-risk populations. Here we describe the study protocol for the CBT-ENDURE trial: Cognitive Behavioral Therapy Following Esketamine for Major Depression and SUicidal Ideation for RElapse Prevention. Patients with depression (N = 100) who are admitted to hospital or are outpatients with clinically significant suicidal ideation will be enrolled in the study. All patients will receive esketamine (twice weekly for four weeks) and will be randomly assigned (1:1 ratio) to receive a 16-week course of CBT plus treatment as usual (CBT group) or treatment as usual only (TAU only group). Patients are followed for a total of 6 months. Supported under a funding announcement from NIMH to conduct safety and feasibility trials for patients at high risk for suicide, the primary outcome of the CBT-ENDURE study is feasibility (as measured by recruitment and retention), with a key secondary outcome being relapse among those who experience substantial benefit following two weeks of esketamine.

Establishing an esketamine clinic in Australia: Practical recommendations and clinical guidance from an expert panel

BACKGROUND

Major depressive disorder (MDD) can have severe impacts on function and quality of life. Up to one third of patients will have an inadequate response to their first line of treatment, with subsequent lines of therapy associated with lower remission rates and higher relapse rates. Recently esketamine has become available for Australian patients, and this agent provides an additional treatment option for those with MDD who have had an inadequate response to two or more antidepressant therapies during the current moderate to severe depressive episode. This paper provides an expert panel's practical recommendations and clinical guidance for establishing esketamine clinics in Australia.

METHODS

An expert panel (n = 11) comprising psychiatrists, mental health care nurses, pharmacists, and individuals with experience establishing esketamine clinics was convened in Sydney. The panel developed practical recommendations and clinical guidance, which were then further refined.

RESULTS

Five key areas were identified: practical considerations for esketamine clinic set-up, including multidisciplinary care considerations; patient selection; administering esketamine; adverse event management and long-term follow-up.

CONCLUSIONS

Guidance presented in this paper should assist Australian clinicians to set up an esketamine clinic, and provide practical advice on the infrastructure and clinical requirements for treatment of patients with this agent.

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.

Indirect adjusted comparison of 6-month clinical outcomes between esketamine nasal spray and other real-world polypharmacy treatment strategies for treatment resistant depression: results from the ICEBERG study

Background

The efficacy of esketamine nasal spray (NS) as a rapid-acting agent for treatment resistant depression (TRD) was demonstrated in comparisons with placebo, when both were given in addition to a newly initiated selective serotonin reuptake inhibitor (SSRI)/serotonin norepinephrine reuptake inhibitor (SNRI). How esketamine NS compares with commonly used real-world (RW) polypharmacy treatment strategies is not known.

Method

ICEBERG was an adjusted indirect treatment comparison that analysed data from SUSTAIN-2 (NCT02497287; clinicaltrials.gov), a long-term, open-label study of esketamine NS plus SSRI/SNRI, and the European Observational TRD Cohort (EOTC; NCT03373253; clinicaltrials.gov), an observational study of routine clinical practice. Data were compared between patients receiving esketamine NS (SUSTAIN-2) and those from the EOTC treated with polypharmacy treatment strategies, either combination or augmentation. Analyses were adjusted for potential confounders, using rescaled average treatment effect among treated estimates. Threshold analyses were conducted to assess potential impact of unmeasured confounders on the robustness of analyses where esketamine NS was found to be significantly superior. Sensitivity analyses were used to understand the impact of analysis method selection and data handling.

Results

Esketamine NS treatment resulted in a higher probability of 6-month response (49.7% [95% confidence interval (CI) 45.6-53.9]) and remission (33.6% [95% CI 29.7-37.6]) versus RW polypharmacy (26.8% [95% CI 21.0-32.5] and 19.4%, [95% CI 14.2-24.6], respectively). Relative risk calculations showed esketamine NS was 1.859 (95% CI 1.474-2.345; p < 0.0001) times as likely to result in response and 1.735 (1.297-2.322; p = 0.0002) times as likely to result in remission versus RW polypharmacy at 6 months. Threshold and extensive sensitivity analyses supported that analyses of esketamine NS superiority were robust.

Conclusion

ICEBERG supports esketamine NS being superior to current RW individualized polypharmacy strategies, including augmentation, with benefits extending beyond acute use, to improved chance of 6-month response and remission. While unobserved confounding factors may certainly impact results of an indirect comparison, threshold analysis supported a low likelihood of this affecting the conclusions.To view an animated summary of this publication, please click on the Supplementary video.

ICEBERG study: an indirect adjusted comparison estimating the long-term benefit of esketamine nasal spray when compared with routine treatment of treatment resistant depression in general psychiatry

Background

Treatment resistant depression (TRD) affects 10-30% of patients with major depressive disorder. In 4-week trials, esketamine nasal spray (NS) was efficacious vs. placebo when both were initiated in addition to a new selective serotonin or serotonin norepinephrine reuptake inhibitor. However, comparison with an extended range of real-world treatments (RWT) is lacking.

Methods

ICEBERG was an adjusted indirect treatment comparison using propensity score-based inverse probability weighting, performed on 6-month response and remission data from patients receiving esketamine NS plus oral antidepressant from the SUSTAIN-2 (NCT02497287; clinicaltrials.gov) study, compared with patients receiving other RWT from the European Observational TRD Cohort (EOTC; NCT03373253; clinicaltrials.gov) study. SUSTAIN-2 was a long-term open-label study of esketamine NS, while the EOTC was conducted at a time when esketamine NS was not available as RWT. Threshold and sensitivity analyses were conducted to assess how robust the primary analyses were.

Results

Patients receiving esketamine NS had a higher probability of 6-month response (49.7% [95% confidence interval (CI) 45.6-53.9]) and remission (33.6% [95% CI 29.7-37.6]) vs. patients receiving RWT (26.4% [95% CI 21.5-31.4] and 18.2% [95% CI 13.9-22.5], respectively), according to rescaled average treatment effect among treated estimates. Resulting adjusted odds ratios (OR) and relative risk (RR) favoured esketamine NS over RWT for 6-month response (OR 2.756 [95% CI 2.034-3.733], p < 0.0001; RR 1.882 [95% CI 1.534-2.310], p < 0.0001) and remission (OR 2.276 [95% CI 1.621-3.196], p < 0.0001; RR 1.847 [95% CI 1.418-2.406], p < 0.0001). Threshold analyses suggested that differences between the two studies were robust, and results were consistent across extensive sensitivity analyses.

Conclusion

ICEBERG supports that, at 6 months, esketamine NS has a substantial and significant benefit over RWT for patients with TRD. While results may be affected by unobserved confounding factors, threshold analyses suggested these were unlikely to impact the study conclusions.To view an animated summary of this publication, please click on the Supplementary video.

Esketamine Nasal Spray versus Quetiapine for Treatment-Resistant Depression

BACKGROUND

In treatment-resistant depression, commonly defined as a lack of response to two or more consecutive treatments during the current depressive episode, the percentage of patients with remission is low and the percentage with relapse is high. The efficacy and safety of esketamine nasal spray as compared with extended-release quetiapine augmentation therapy, both in combination with ongoing treatment with a selective serotonin reuptake inhibitor (SSRI) or a serotonin-norepinephrine reuptake inhibitor (SNRI), in patients with treatment-resistant depression are unknown.

METHODS

In an open-label, single-blind (with raters unaware of group assignments), multicenter, phase 3b, randomized, active-controlled trial, we assigned patients, in a 1:1 ratio, to receive flexible doses (according to the summary of product characteristics) of esketamine nasal spray (esketamine group) or extended-release quetiapine (quetiapine group), both in combination with an SSRI or SNRI. The primary end point was remission, defined as a score of 10 or less on the Montgomery-Åsberg Depression Rating Scale (MADRS), at week 8 (scores range from 0 to 60, with higher scores indicating more severe depression). The key secondary end point was no relapse through week 32 after remission at week 8. All patients were included in the analysis; patients who discontinued the trial treatment were considered as having had an unfavorable outcome (i.e., they were grouped with patients who did not have remission or who had a relapse). Analyses of the primary and key secondary end points were adjusted for age and number of treatment failures.

RESULTS

Overall, 336 patients were assigned to the esketamine group and 340 to the quetiapine group. More patients in the esketamine group than in the quetiapine group had remission at week 8 (91 of 336 patients [27.1%] vs. 60 of 340 patients [17.6%]; P = 0.003) and had no relapse through week 32 after remission at week 8 (73 of 336 patients [21.7%] vs. 48 of 340 patients [14.1%]). Over 32 weeks of follow-up, the percentage of patients with remission, the percentage of patients with a treatment response, and the change in the MADRS score from baseline favored esketamine nasal spray. The adverse events were consistent with the established safety profiles of the trial treatments.

CONCLUSIONS

In patients with treatment-resistant depression, esketamine nasal spray plus an SSRI or SNRI was superior to extended-release quetiapine plus an SSRI or SNRI with respect to remission at week 8. (Funded by Janssen EMEA; ESCAPE-TRD ClinicalTrials.gov number, NCT04338321.).

Treatment-resistant depression: definition, prevalence, detection, management, and investigational interventions

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.

Short-term cognitive effects of repeated-dose esketamine in adolescents with major depressive disorder and suicidal ideation: a randomized controlled trial

BACKGROUND

Ketamine and its enantiomer have rapid and robust effects on depressive symptom and suicidal ideation. Little is known about their cognitive effects in adolescents. We aimed to evaluate the short-term effect of esketamine on cognition in adolescents with major depressive disorder (MDD) and suicidal ideation.

METHOD

In this randomized-controlled trial, 51 participants aged 13-18 with MDD and suicidal ideation received three intravenous infusions of either esketamine (0.25 mg/kg) or midazolam (0.02 mg/kg). Four dimensions of the MATRICS Consensus Cognitive Battery (MCCB), including processing speed, working memory, verbal learning and visual learning, were assessed at Days 0, 6 and 12.

RESULTS

In the linear mixed model, a significant time main effect (F = 12.803, P < 0.001), drug main effect (F = 6.607, P = 0.013), and interaction effect (F = 3.315, P = 0.041) was found in processing speed. Other dimensions including working memory and verbal learning showed significant time main effect (all P < 0.05), but no significant drug or interaction effect (all P > 0.05). Esketamine group showed improvement in processing speed from baseline to Days 6 and 12, and working memory from baseline to Day 12 (all P < 0.05). The generalized estimation equation showed no significant association between baseline cognition and antidepressant or antisuicidal effect (both P > 0.05).

CONCLUSIONS

The present study suggested that three-dose subanesthetic esketamine infusions did not harm cognition among adolescents with MDD and suicidal ideation. Instead, esketamine may be associated with improvement in processing speed.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trials Registry ( http://www.chictr.org.cn , ChiCTR2000041232).

Esketamine in treatment-resistant depression patients comorbid with substance-use disorder: A viewpoint on its safety and effectiveness in a subsample of patients from the REAL-ESK study

Esketamine, the S-enantiomer of ketamine, has recently emerged as a therapy for treatment-resistant depression (TRD), showing both rapid antidepressant action and good efficacy and high safety. It is also indicated for the acute short-term treatment of psychiatric emergency due to major depressive disorder (MDD) and for depressive symptoms in adults with MDD with acute suicidal thoughts/behavior. We here provide preliminary insights on esketamine nasal spray (ESK-NS) effectiveness and safety among patients with a substance use disorder (SUD) within the sample of patients with TRD collected for the observational, retrospective, multicentre REAL-ESK study. Twenty-six subjects were retrospectively selected according to the presence of a SUD in comorbidity. Subjects enrolled completed the three different follow-up phases (T0/baseline, T1/after one month, and T2/after three months) and there were no dropouts. A decrease in Montgomery-Asberg depression rating scale (MADRS) scores was recorded, thus highlighting the antidepressant efficacy of ESK-NS (MADRS decreased from T0 to T1, t = 6.533, df=23, p<0.001, and from T1 to T2, t = 2.029, df=20, p = 0.056). Considering tolerability and safety issues, one or more side effects were reported by 19/26 subjects (73%) after treatment administration. All reported side effects were time-dependent and did not cause significant sequelae; among them, dissociative symptoms (38%) and sedation (26%) were the most frequently reported. Finally, no cases of abuse or misuse of ESK-NS were reported. Despite study limitations related to the inherent nature of the study, a limited number of patients, and a short follow-up period, ESK-NS showed to be effective and safe in patients diagnosed with TRD comorbid with a SUD.

Therapeutic Protocols Using Ketamine and Esketamine for Depressive Disorders: A Systematic Review

Depression is one of the most prevalent mental health disorders globally, causing severe emotional suffering, reducing life expectancy and increasing the risk of suicide. Recently, the use of dissociative psychedelic substances such as ketamine and esketamine for depressive disorders has expanded treatment options. We sought to analyze, through a systematic review, the existing protocols for the treatment of depression with ketamine and esketamine. The search adopted PRISMA criteria and was performed using PubMed and Web of Science databases. Procedures in each study were compared, focusing on the sample recruited, therapeutic approaches, including the clinical team and professionals engaged in treatment, medical procedures, description of the setting (including music) and factors such as specific medication (ketamine or esketamine), route of administration and dosage employed. Results indicated the predominance of a medical approach, with a limited number of studies on ketamine assisted psychotherapy (KAP) and other modalities of psychedelic assisted therapy. Additionally, there is limited information on psychosocial elements such as preparation, psychological support during session and integration of experience. Altogether these findings suggest that treatment of depression with ketamine or esketamine diverges in relation to the practices employed with psychedelic substances. This is discussed considering future research directions in the field.

Commentary on Cochrane review: "Ketamine and other glutamate receptor modulators for depression in adults with unipolar major depressive disorder"

BACKGROUND

Cochrane recently published a review of esketamine and other glutamate receptor modulators in depression.

AIM

To address the limitations of the review, analyses of esketamine data were conducted to provide additional perspective to the reviewers' interpretation of their findings.

METHODS

Response rate, remission rate, and change from baseline in Montgomery-Åsberg Depression Rating Scale (MADRS) total score were determined using data from all esketamine phase 2/3 registration studies of treatment-resistant depression (TRD) and, separately, all esketamine phase 2/3 registration studies of major depressive disorder (MDD) and active suicidal ideation with intent. Outcomes were assessed at all timepoints (i.e., 24 h, 72 h (MDD with active suicidal intent only), and 1, 2, and 4 weeks). Enrollment criteria of the TRD studies were different than those of the studies of MDD and active suicidal ideation with intent, resulting in differences in patients' clinical characteristics and depression severity between the cohorts. Thus, we did not compare results between these cohorts (as was done in the Cochrane review).

RESULTS/OUTCOMES

In the combined TRD studies, a statistically significant between-group difference favored esketamine plus antidepressant over antidepressant plus placebo at 24 h (based on response, remission, and change in MADRS score), 1 week (change in MADRS score), 2 weeks (response and change in MADRS score), and 4 weeks (response, remission, and change in MADRS score). In the combined studies of MDD and active suicidal ideation with intent, the between-group difference was statistically different, favoring esketamine plus standard-of-care over placebo plus standard-of-care, at 24 h (response, remission, and change in MADRS score), 72 h and 1 week (change in MADRS score), 2 weeks (response), and 4 weeks (response, remission, and change in MADRS score). For both study types, the between-group difference in outcomes was not statistically significant at the other timepoints.

CONCLUSIONS/INTERPRETATION

Esketamine improves response, remission, and depressive symptoms as early as 24 h post-first dose among patients with TRD and among patients with MDD and active suicidal ideation with intent.

Efficacy and Safety of Esketamine Nasal Spray in Patients with Treatment-Resistant Depression Who Completed a Second Induction Period: Analysis of the Ongoing SUSTAIN-3 Study

BACKGROUND

Treatment-resistant depression (TRD) is a chronic illness requiring long-term treatment. Esketamine nasal spray (ESK) has been studied in several long-term trials of patients with TRD, including SUSTAIN-1 (NCT02493868) and SUSTAIN-3 (NCT02782104). This subgroup analysis of SUSTAIN-3 evaluated patients with TRD who received a second induction (IND) and maintenance treatment with ESK plus oral antidepressant (AD) after a relapse in SUSTAIN-1.

METHODS

Patients aged 18-64 years who achieved stable remission or response with ESK and subsequently relapsed after randomization to continue ESK or switch to placebo nasal spray (PBO) in SUSTAIN-1 and entered the IND phase of SUSTAIN-3 were included in this interim analysis. Response (≥50% improvement in total score from baseline for Montgomery-Åsberg Depression Rating Scale [MADRS] and Patient Health Questionnaire 9-item [PHQ-9]), remission (MADRS score ≤12; PHQ-9 total score <5), changes in depression rating scores (measured as mean change from baseline), and safety were evaluated (incidence of treatment-emergent and serious adverse events [AE]).

RESULTS

Of the 96 eligible patients who entered IND in SUSTAIN-3, 32 (33.3%) were taking ESK+AD at the time of relapse in SUSTAIN-1 and 64 (66.7%) were taking AD+PBO. Substantial improvements in depressive symptoms were observed over the second IND phase in both groups and were maintained over the optimization/maintenance (OP/M) phase. MADRS response rates following a second IND were 71.9% and 73.4% for previously relapsed (PR) ESK+AD and PR-AD+PBO, respectively; remission rates were 62.5% and 60.9%, respectively. During the IND and OP/M phases, 58.3% and 83.3% of patients experienced a treatment-emergent AE, respectively. No patients discontinued due to an AE during the second IND.

CONCLUSIONS

Patients with TRD benefitted from receiving a second IND and maintenance treatment with ESK and no new safety signals were identified.

Long-term safety and maintenance of response with esketamine nasal spray in participants with treatment-resistant depression: interim results of the SUSTAIN-3 study

Patients with treatment-resistant depression (TRD) have higher rates of relapse and pronounced decreases in daily functioning and health-related quality of life compared to patients with major depressive disorder who are not treatment-resistant, underscoring the need for treatment choices with sustained efficacy and long-term tolerability. Adults with TRD who participated in ≥1 of 6 phase 3 "parent" studies could continue esketamine treatment, combined with an oral antidepressant, by enrolling in phase 3, open-label, long-term extension study, SUSTAIN-3. Based on their status at parent-study end, eligible participants entered a 4-week induction phase followed by an optimization/maintenance phase, or directly entered the optimization/maintenance phase of SUSTAIN-3. Intranasal esketamine dosing was flexible, twice-weekly during induction and individualized to depression severity during optimization/maintenance. At the interim data cutoff (01 December 2020), 1148 participants were enrolled, 458 at induction and 690 at optimization/maintenance. Mean (median) cumulative duration of maintenance esketamine treatment was 31.5 (37.7) months (totaling 2769 cumulative patient-years). Common treatment-emergent adverse events (≥20%) were headache, dizziness, nausea, dissociation, somnolence, and nasopharyngitis. Mean Montgomery-Åsberg Depression Rating Scale (MADRS) total score decreased during induction, and this reduction persisted during optimization/maintenance (mean [SD] change from the baseline to the endpoint of each phase: induction -12.8 [9.73]; optimization/maintenance +1.1 [9.93]), with 35.6% and 46.1% of participants in remission (MADRS total score ≤12) at induction and optimization/maintenance endpoints, respectively. Improvement in depression ratings generally persisted among participants who remained in maintenance treatment, and no new safety signal was identified during long-term treatment (up to 4.5 years) using intermittent-dosed esketamine in conjunction with daily antidepressant.

Reporting of harms in clinical trials of esketamine in depression: a systematic review

While previous systematic reviews of trials evaluating conventional antidepressants highlighted inadequacies and inconsistencies in adverse event (AE) reporting, no evaluation is available on esketamine in resistant depression. The objective of this review was to assess quality of reporting AEs in all published clinical trials studying esketamine. It also aimed to compare the proportions of AEs reported in journal articles to those recorded in the ClinicalTrial.gov Registers. Clinical trials evaluating the efficacy and safety of esketamine in depression were searched using Medline and ClinicalTrials.gov. The quality of reporting harms was assessed using a 21-item checklist from the CONSORT Extension of Harms (1 point by item). The total quality score was graded into four categories: high (17-21), moderate (12-16), low (7-11) and very low (0-6). Ten clinical trials were included in the analysis. Nine trials were classified as 'low quality' with regard to safety, one trial was classified as 'moderate quality'. Compared to AEs recorded in ClinicalTrials.gov, we found that 41.5% of serious AEs and 39% of non-serious AEs were not reported in the published articles. Among them, the majority were psychiatric events but also cardiovascular events and 94% concerned patients from esketamine groups. Quality of AEs reporting in published clinical trials of esketamine was poor and harms were reported less frequently in journal publications than in ClinicalTrial.gov Registers. The study suggests that an assessment of the benefits/risks balance of esketamine based on the results reported in trial publications is flawed due to the poor accuracy and completeness of harm data.

Reduction in Cognitive Symptoms Following Intranasal Esketamine Administration in Patients With Chronic Treatment-resistant Depression: A 12-Week Case Series

BACKGROUND

Cognitive symptoms are a core feature of depressive disorders, interfere with full functional recovery and are prominent in patients with treatment-resistant depression (TRD), particularly in severe chronic cases. Intranasal (IN) esketamine was recently approved for the treatment of TRD; however, its effects on cognitive symptoms are unclear. In this article, we describe cognitive changes in 8 patients with chronic TRD who were treated with IN administration of esketamine.

METHODS

Eight outpatients with chronic TRD received IN esketamine over 3 months and were assessed at baseline and after 4, 8, and 12 weeks of treatment using the Montgomery-Åsberg Depression Rating Scale (MADRS), the Digit Symbol Substitution Test (DSST), the Trail Making Test-B (TMT-B), the Patient Deficits Questionnaire for Depression 5-item (PDQ-D5), the Hamilton Anxiety Rating Scale (HARS), and the Clinical Global Impressions Scale (CGI).

FINDINGS

We observed reductions in cognitive symptoms according to DSST, TMT-B, and PDQ-D5 scores within the first 2 months of treatment with IN esketamine. These improvements were observed before patients achieved clinical response (≥50% decrease in baseline MADRS scores), and they also occurred earlier than reductions in HARS scores.

CONCLUSIONS

A clinical response to IN esketamine was detected in severely ill patients with chronic TRD after 3 months of treatment. Interestingly, improvements on measures of cognitive symptoms were observed before patients achieved antidepressant response. These preliminary observations suggest an additional value to the antidepressant properties of IN esketamine. Clinical studies specifically investigating cognition as a primary outcome measure of IN esketamine in TRD are warranted.

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.

Ketamine and the Disinhibition Hypothesis: Neurotrophic Factor-Mediated Treatment of Depression

Ketamine is a promising alternative to traditional pharmacotherapies for major depressive disorder, treatment-resistant depression, and other psychiatric conditions that heavily contribute to the global disease burden. In contrast to the current standard of care medications for these disorders, ketamine offers rapid onset, enduring clinical efficacy, and unique therapeutic potential for use in acute, psychiatric emergencies. This narrative presents an alternative framework for understanding depression, as mounting evidence supports a neuronal atrophy and synaptic disconnection theory, rather than the prevailing monoamine depletion hypothesis. In this context, we describe ketamine, its enantiomers, and various metabolites in a range of mechanistic actions through multiple converging pathways, including N-methyl-D-aspartate receptor (NMDAR) inhibition and the enhancement of glutamatergic signaling. We describe the disinhibition hypothesis, which posits that ketamine's pharmacological action ultimately results in excitatory cortical disinhibition, causing the release of neurotrophic factors, the most important of which is brain-derived neurotrophic factor (BDNF). BDNF-mediated signaling along with vascular endothelial growth factor (VEGF) and insulin-like growth factor 1 (IGF-1) subsequently give rise to the repair of neuro-structural abnormalities in patients with depressive disorders. Ketamine's efficacious amelioration of treatment-resistant depression is revolutionizing psychiatric treatment and opening up fresh vistas for understanding the underlying causes of mental illness.

Treating bipolar depression with esketamine: Safety and effectiveness data from a naturalistic multicentric study on esketamine in bipolar versus unipolar treatment-resistant depression

BACKGROUND

Bipolar depression accounts for most of the disease duration in type I and type II bipolar disorder (BD), with few treatment options, often poorly tolerated. Many individuals do not respond to first-line therapeutic options, resulting in treatment-resistant bipolar depression (B-TRD). Esketamine, the S-enantiomer of ketamine, has recently been approved for treatment-resistant depression (TRD), but no data are available on its use in B-TRD.

OBJECTIVES

To compare the efficacy of esketamine in two samples of unipolar and bipolar TRD, providing preliminary indications of its effectiveness in B-TRD. Secondary outcomes included the evaluation of the safety and tolerability of esketamine in B-TRD, focusing on the average risk of an affective switch.

METHODS

Thirty-five B-TRD subjects treated with esketamine nasal spray were enrolled and compared with 35 TRD patients. Anamnestic data and psychometric assessments (Montgomery-Asberg Depression Rating Scale/MADRS, Hamilton-depression scale/HAM-D, Hamilton-anxiety scale/HAM-A) were collected at baseline (T0), at one month (T1), and three months (T2) follow up.

RESULTS

A significant reduction in depressive symptoms was found at T1 and T2 compared to T0, with no significant differences in response or remission rates between subjects with B-TRD and TRD. Esketamine showed a greater anxiolytic action in subjects with B-TRD than in those with TRD. Improvement in depressive symptoms was not associated with treatment-emergent affective switch.

CONCLUSIONS

Our results supported the effectiveness and tolerability of esketamine in a real-world population of subjects with B-TRD. The low risk of manic switch in B-TRD patients confirmed the safety of this treatment.

Neurocognitive effects of subanesthetic serial ketamine infusions in treatment resistant depression

INTRODUCTION

Ketamine treatment prompts a rapid antidepressant response in treatment-resistant depression (TRD). We performed an exploratory investigation of how ketamine treatment in TRD affects different cognitive domains and relates to antidepressant response.

METHODS

Patients with TRD (N = 66; 30 M/35F; age = 39.5 ± 11.1 years) received four ketamine infusions (0.5 mg/kg). Neurocognitive function and depressive symptoms were assessed at baseline, 24 h after the first and fourth ketamine infusion, and 5 weeks following end of treatment. Mixed effect models tested for changes in seven neurocognitive domains and antidepressant response, with post-hoc pairwise comparisons between timepoints, including follow-up. Relationships between change in neurocognitive function and antidepressant response over the course of treatment were tested with Pearson's correlation and mediation analyses. Associations between baseline neurocognitive performance and antidepressant response were tested with Pearson's correlation.

RESULTS

Significant improvements in inhibition, working memory, processing speed, and overall fluid cognition were observed after the first and fourth ketamine infusion. Improvements in processing speed and overall fluid cognition persisted through follow-up. Significant improvements in depressive symptoms reverted towards baseline at follow-up. Baseline working memory and change in inhibition were moderately correlated with antidepressant response, however, improvements in neurocognitive performance were statistically independent from antidepressant response.

CONCLUSION

Antidepressant ketamine leads to improved neurocognitive function, which persist for at least 5 weeks. Neurocognitive improvements observed appear independent of antidepressant response, suggesting ketamine may target overlapping but distinct functional brain systems. Limitations Research investigating repeated serial ketamine treatments is important to determine cognitive safety. This study is a naturalistic design and does not include placebo.

Adverse Events and Measurement of Dissociation After the First Dose of Esketamine in Patients With TRD

BACKGROUND

"Dissociation" comprises distinct phenomena, some of which are associated with esketamine treatment and some may overlap with positive symptoms of psychosis. Relationships between dissociation and psychotic symptoms assessed by -clinician report vs conventional rating scales were investigated in a post hoc analysis of data from the initial treatment session in an -open-label, -long-term safety, phase 3 study of esketamine plus a newly initiated oral antidepressant in patients with treatment-resistant depression.

METHODS

Adverse events of dissociation or psychosis were examined via investigator report and the Clinician Administered Dissociative States Scale (CADSS) and Brief Psychiatric Rating Scale-Plus, respectively, 40 minutes post first esketamine dose. The range of CADSS total scores associated with investigator-reported severity of dissociation was determined by equipercentile linking. Logistic regression models and receiver operating curve analysis explored the CADSS cutoff point for determining presence/absence of dissociation. Frequency of response to specific CADSS items was examined to investigate qualitative differences in the pattern of symptoms reported across investigator-reported levels of adverse event severity.

RESULTS

Dissociation was reported as an adverse event in 14.3% (109/764) of patients. Severity of most CADSS items increased with the severity of investigator-reported dissociation. No CADSS cutoff point discriminated well between the presence and absence of dissociation events. Hallucinations were reported as adverse events in 5 patients; none reported delusions.

CONCLUSIONS

CADSS scores and severity of dissociation adverse events move generally in the same direction; however, there is substantial variability in this relationship. No signature profile of dissociative experiences was revealed, and psychotic symptoms were uncommon.

TRIAL REGISTRATION

Clinical Trials.gov identifier: NCT02497287.

Role of group II metabotropic glutamate receptors in ketamine's antidepressant actions

Major Depressive Disorder (MDD) is a serious neuropsychiatric disorder afflicting around 16-17 % of the global population and is accompanied by recurrent episodes of low mood, hopelessness and suicidal thoughts. Current pharmacological interventions take several weeks to even months for an improvement in depressive symptoms to emerge, with a significant percentage of individuals not responding to these medications at all, thus highlighting the need for rapid and effective next-generation treatments for MDD. Pre-clinical studies in animals have demonstrated that antagonists of the metabotropic glutamate receptor subtype 2/3 (mGlu_2/3 receptor) exert rapid antidepressant-like effects, comparable to the actions of ketamine. Therefore, it is possible that mGlu₂ or mGlu₃ receptors to have a regulatory role on the unique antidepressant properties of ketamine, or that convergent intracellular mechanisms exist between mGlu_2/3 receptor signaling and ketamine's effects. Here, we provide a comprehensive and critical evaluation of the literature on these convergent processes underlying the antidepressant action of mGlu_2/3 receptor inhibitors and ketamine. Importantly, combining sub-threshold doses of mGlu_2/3 receptor inhibitors with sub-antidepressant ketamine doses induce synergistic antidepressant-relevant behavioral effects. We review the evidence supporting these combinatorial effects since sub-effective dosages of mGlu_2/3 receptor antagonists and ketamine could reduce the risk for the emergence of significant adverse events compared with taking normal dosages. Overall, deconvolution of ketamine's pharmacological targets will give critical insights to influence the development of next-generation antidepressant treatments with rapid actions.

Novel antidepressant drugs: Beyond monoamine targets

Treatment of major depressive disorder (MDD) including treatment-resistant depression (TRD) remains a major unmet need. Although there are several classes of dissimilar antidepressant drugs approved for MDD, the current drugs have either limited efficacy or are associated with undesirable side effects and withdrawal symptoms. The efficacy and side effects of antidepressant drugs are mainly attributed to their actions on different monoamine neurotransmitters (serotonin, norepinephrine, and dopamine). Development of new antidepressants with novel targets beyond the monoamine pathways may fill the unmet need in treatment of MDD and TRD. The recent approval of intranasal Esketamine (glutamatergic agent) in conjunction with an oral antidepressant for the treatment of adult TRD patients was the first step toward expanding beyond the monoamine targets. Several other glutamatergic (AXS-05, REL-1017, AV-101, SLS-002, AGN24175, and PCN-101) and GABAergic (brexanolone, zuranolone, and ganaxolone) drugs are currently in different stages of clinical development for MDD, TRD and other indications. The renaissance of psychedelic drugs and the emergence of preliminary positive clinical trial results with psilocybin, Ayahuasca, 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), and lysergic acid diethylamide (LSD) may pave the way towards establishing this class of drugs as effective therapies for MDD, TRD and other neuropsychiatric disorders. Going beyond the monoamine targets appears to be an effective strategy to develop novel antidepressant drugs with superior efficacy, safety, and tolerability for the improved treatment of MDD and TRD.

Cost-Utility Analysis of Esketamine for Patients with Treatment-Resistant Depression in Italy

AIM

Major depressive disorder is considered one of the most frequent diseases in the general population, and treatment-resistant depression (TRD) represents the subset with more significant clinical and social impact. Large, robust phase III studies have shown safety and efficacy of esketamine nasal spray plus SSRI/SNRI antidepressants (ADs) compared with SSRI/SNRI plus placebo nasal spray in patients with TRD. The main aim of this study was to perform a cost-utility analysis comparing esketamine plus ADs with ADs alone in TRD patients, from the societal perspective in Italy. A secondary analysis focused on the National Healthcare Service (NHS) perspective.

METHODS

A Markov multistate model has been developed to estimate quality-adjusted life years and economic outcomes of both treatment strategies over 5 years considering the initiation of esketamine in the different treatment lines, from 3 to 5 (3L-5L). The model has been populated with data from literature and real-world evidence. The analysis from the societal perspective considered direct healthcare costs and patients' productivity losses. In addition to the incremental cost-utility ratio (ICUR), the incremental net monetary benefit (INMB) has been calculated as (incremental benefit × WTP) - incremental cost and by applying a willingness-to-pay (WTP) of 50,000€/QALY. Deterministic and probabilistic sensitivity analyses have been performed to assess the robustness of the model results.

RESULTS

From the societal perspective, the ICUR ranged between 16,314€ and 22,133€ per QALY according to the different treatment lines, while it was over the threshold of 100,000€/QALY for the NHS perspective. The INMB was positive and ranged from 2259€ to 2744€ across treatment lines in the societal perspective; the INMB begins to occur earlier when moving towards subsequent lines of treatment (3.9 years for 3L, 3.6 years for 4L and 3.5 years for 5L). The analyses showed also that the advantage in terms of INMB is maintained for a wide range of societal preferences expressed by WTP thresholds, and in particular for values above 22,200€, 16,400€ and 17,100€ for 3L, 4L and 5L, respectively.

CONCLUSION

The study showed that esketamine may be a cost-effective opportunity from the societal perspective for the management of patients with treatment-resistant depression. In the future, data collected from observational studies or registries, which can include the collection of productivity losses and also costs sustained by the patients, will be able to provide further evidence in order to improve the reliability of the model results.

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.

Esketamine for treatment‑resistant depression: A review of clinical evidence (Review)

Treatment-resistant depression (TRD) is a challenge for psychiatrists, even after more than seven decades since the first antidepressants were used in clinical practice. Non-monoaminergic-based drugs with antidepressant properties have been developed, but to date, only esketamine and brexanolone have been approved for TRD and postpartum depression, respectively. A narrative review on the efficacy and safety of esketamine in the main categories of depressive disorders has been conducted through four electronic databases (Pubmed, Cochrane, EMBASE and Clarivate/Web of Science) The primary objective of the present review was to find evidence that may support the usefulness of esketamine for patients diagnosed with TRD as well as data about its potential adverse effects in the short and long term. A total of 14 papers were reviewed, and their results support the recommendation of esketamine for treatment of TRD as an add-on to antidepressants, but more data is needed in order to assess its long-term efficacy and safety. It must also be mentioned that there have been a few trials which did not report a significant effect on the severity of depressive symptoms with esketamine in TRD, therefore, caution is indicated for patients initiated on this adjuvant agent. There has been insufficient data to formulate specific guidelines about esketamine administration because evidence about favorable or negative prognostic factors of this treatment has been lacking, and the duration of its administration has not been unanimously accepted. Novel directions for research have been identified, especially in the case of patients with TRD and substance use disorders, geriatric or bipolar depression or in major depression with psychotic features.