Ketamine for Treatment of Suicidal Ideation and Reduction of Risk for Suicidal Behavior

Molecular mechanisms underlying the N-methyl-d-aspartate receptor antagonists: Highlighting their potential for transdiagnostic therapeutics

The so-called "psychedelic renaissance" has stimulated expanded interest in several classes of drugs that appear to possess transdiagnostic effects in the treatment of mental health disorders, specifically. N-methyl-d-aspartate receptor (NMDAR) antagonists are one such class with diverse therapeutic potential. NMDARs mediate excitatory postsynaptic signalling in the central nervous system (CNS) and are integral to normal neurobiological processes including neuronal development, synaptic transmission, and plasticity, and thus involved in learning and memory. However, NMDAR hyper-function is also implicated in acute CNS trauma, neuropsychiatric and neurodegenerative disorders, as well as chronic pain. The complex structure of NMDARs permits several locations for therapeutic inhibition, making these receptors a potential target for multiple drugs which modulate them in different ways. NMDAR antagonists, which may be competitive, non-competitive, or uncompetitive, either block glutamate from binding the receptor or modulate the response to glutamate binding. Despite longstanding concerns about side effects of NMDAR antagonists, recent research suggests that, when appropriately used, these agents have favourable safety profiles. Furthermore, their fast-acting mechanism of action, resulting in rapid effects compared to other therapeutic agents, makes them a promising class of drugs that may yield effective therapeutics for multiple CNS disorders.

(Es)Ketamine for Suicidal Ideation and Behavior: Clinical Efficacy

Suicidal ideation and behavior are among the most severe psychiatric presentations, warranting emergency room visits and psychiatric admission for higher levels of care. In the United States, suicide rates continue to climb, especially in younger patients, and the continued psychosocial stressors of the COVID-19 pandemic may further exacerbate this crisis. Suicidal ideation and behavior are core features of a major depressive episode, but there are limited treatment options to rapidly redress these life-threatening symptoms. Racemic ketamine and its S-enantiomer, esketamine, are N-methyl-D-aspartate receptor antagonists and glutamate modulators that have robust antidepressant efficacy in treatment-resistant major depressive disorder and bipolar depression. Additionally, both ketamine and esketamine have demonstrated rapid-acting antisuicidal efficacy in major mood disorders. In August 2020, this culminated in a first-in-class approval of Spravato® (intranasal esketamine) for the treatment of major depressive disorder with acute suicidal ideation and behavior. In this article, we review the literature in support of the antisuicidal efficacy of ketamine and esketamine.

Single, Fixed-Dose Intranasal Ketamine for Alleviation of Acute Suicidal Ideation. An Emergency Department, Trans-Diagnostic Approach: A Randomized, Double-Blind, Placebo-Controlled, Proof-of-Concept Trial

BACKGROUND

Suicidal patients often present to the emergency department, where specific anti-suicidal treatment is lacking. Ketamine, a Glutamate modulator and a rapidly acting antidepressant with anti-suicidal properties, might offer relief.

AIMS

Evaluation of single, fixed-dosed intranasal ketamine for acute suicidal ideation in the emergency department.

METHODS

Between August 2016 and April 2018, 30 eligible suicidal subjects, scheduled for psychiatric hospitalization, independently of their psychiatric diagnosis, were randomized to intranasal ketamine 40 mg or saline placebo. Safety and efficacy evaluations were scheduled for 30, 60, 120 and 240 min post administration and on days 1, 2, 3, 4, 5, 7, 21 and 28. Primary outcome was suicidal ideation.

RESULTS

Fifteen subjects were randomized for each study group. All were analyzed for primary and secondary outcomes. Four hours post administration, the mean difference in suicidal symptoms between the groups, measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) item of suicidal thoughts (MADRS-SI), was 1.267 (95% confident interval 0.1-2.43, p < 0.05) favoring treatment. Remission from suicidal ideation was evident in 80% for the ketamine group compared with 33% for the controls (p < 0.05). The mean difference in depressive symptoms, measured by MADRS, at the same time was 9.75 (95% confident interval 0.72-18.79, p < 0.05) favoring ketamine. Treatment was safe and well-tolerated.

CONCLUSIONS

Single, fixed-dose, intranasal ketamine alleviated suicidal ideation and improved depressive symptoms four hours post administration. We present here an innovative paradigm for emergency department management of suicidal individuals. Future larger-scale studies are warranted. ClinicalTrials.gov Identifier: NCT02183272.

Ketamine vs midazolam: Mood improvement reduces suicidal ideation in depression

OBJECTIVE

Studies demonstrate rapid antidepressant and anti-suicidal ideation effects of subanesthetic ketamine. The specific subcomponents of depression that are most closely tied to reduction of suicidal ideation with ketamine treatment are less explored.

METHODS

Exploratory, post hoc analysis of data from a randomized clinical trial of ketamine vs midazolam in patients with major depressive disorder (MDD) and clinically significant suicidal ideation examined changes in factor analysis-derived symptom clusters from standard measures of depression (Hamilton Depression Rating Scale, HDRS; Beck Depression Inventory, BDI) and mood disturbance (Profile of Mood States, POMS), and their relationship to severity of suicidal ideation (Beck Scale for Suicidal Ideation; SSI). Ratings obtained before and one day after blinded intravenous infusion were decomposed into component factors or published subscales. Treatment effects on factors/subscales were compared between drugs, correlations with changes in suicidal ideation were tested, and stepwise regression was used to derive predictors of change in SSI.

RESULTS

Factor scores for HDRS Psychic Depression, HDRS Anxiety, BDI Subjective Depression, POMS Depression and POMS Fatigue improved more with ketamine than midazolam. Stepwise regression showed across both drugs that improvement in HDRS Psychic Depression, POMS Depression, and HDRS Anxiety predicted 51.6% of the variance in reduction of suicidal ideation.

LIMITATIONS

Secondary analysis of clinical trial data.

CONCLUSIONS

Ketamine's rapid effects on suicidal ideation appear to be mostly a function of its effects on core mood and anxiety symptoms of MDD, with comparatively little contribution from neurovegetative symptoms with the potential exception of vigor/fatigue.

TRIAL REGISTRATION

Data used in this secondary analysis came from ClinicalTrials.gov identifier: NCT01700829.

Switching to Intranasal Esketamine Maintains the Antidepressant Response to Intravenous Racemic Ketamine Administration: A Case Series of 10 Patients

PURPOSE

This study aims to assess the efficacy and safety of intranasal (IN) esketamine as maintenance antidepressant therapy in patients who have demonstrated clinical improvement with off-label intravenous (IV) racemic ketamine for treatment-resistant depression (TRD).

METHODS

This is a retrospective case series of 10 consecutive outpatients with TRD who all had a clinically meaningful response when treated with IV racemic ketamine and were then switched to IN esketamine for maintenance therapy. Patient outcomes were assessed with the Montgomery-Åsberg Depression Rating Scale, Patient Health Questionnaire 9, and Clinical Global Impression of Improvement scale at each visit. Adverse effects were assessed at each treatment.

FINDINGS

Results indicated that 9 patients either maintained the benefit or showed greater improvement when transitioned to IN esketamine for antidepressant maintenance therapy. One patient had worsening of depression due to an acute psychosocial stressor but still improved from baseline IV racemic ketamine treatment. Six patients returned to work or pursued employment, and 4 patients with suicidal ideation remitted during IV racemic ketamine treatment and had no recurrence of suicidality with IN esketamine. No serious adverse reactions or tolerability issues were observed.

IMPLICATIONS

This case series reports the outcomes of 10 severely ill patients with TRD who had a clinically meaningful response to IV racemic ketamine and demonstrated a maintenance of effect or continued improvement when transitioned to IN esketamine. Although this finding needs to be replicated in larger, controlled studies, this report provides promising results for patients who have safely and effectively switched to Food and Drug Administration-approved IN esketamine after receiving acute or maintenance depression treatment with off-label IV racemic ketamine.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.

Ketamine for acute suicidal ideation. An emergency department intervention: A randomized, double-blind, placebo-controlled, proof-of-concept trial

BACKGROUND

Depressed patients presenting to emergency departments with acute suicidal ideation are a major public health concern. Ketamine, a rapidly acting antidepressant with antisuicidal properties, might offer relief.

METHODS

In a randomized, double-blind, placebo-controlled, proof-of-concept trial, 18 depressed subjects with acute suicidal ideation, who required hospitalization, were randomized to either an intravenous ketamine 0.2 mg/kg group or a saline placebo group. Safety and efficacy evaluations were scheduled for 15, 30, 60, 90, 120, 180, and 240 min, and on Days 1, 2, 3, 7, and 14 after infusion. The main outcome measure was suicidal ideation with secondary measures of depression.

RESULTS

Nine subjects were randomized to each group. There were no differences between groups at baseline in any demographic or assessment scales. A reduction in suicidal ideation was noted at 90-180 min (p < .05). Ninety minutes after infusion, 88% of the ketamine group had achieved remission of suicidal ideation compared with 33% in the placebo group (p < .05). No serious adverse events were noted.

CONCLUSIONS

Ketamine was safe and effective for rapid reduction in suicidal ideation in depressed, highly suicidal subjects presenting to the emergency department. Our results support further study of ketamine for acute suicidal ideation.

Infusing hope into the treatment of suicidality: A review of ketamine's effects on suicidality

PURPOSE OF REVIEW

Given recent increases in rates of suicide and lack of rapid treatments for suicidality, ketamine has been identified as a potential fast-acting anti-suicidal treatment. Our review seeks to describe the effects of ketamine on suicidality, given the growing literature on the use of ketamine in reducing suicidality. We examine open-label studies and randomized controlled trials evaluating treatment of suicidality with ketamine. Furthermore, our manuscript identifies potential mechanisms of ketamine's effects on suicidality.

RECENT FINDINGS

Based on existing RCTs, ketamine appears to have rapid anti-suicidal effects, with most literature studying such effects in timeframes less than one week. Although still in the early stages of research, mechanisms of ketamine include modulation of molecular, inflammatory, neural, cognitive, and behavioral processes.

SUMMARY

Thus, ketamine appears to be a promising treatment for suicidality, but requires larger scale and more robust RCTs to confirm the potential use of this agent in clinical settings.

NMDA 2A receptors in parvalbumin cells mediate sex-specific rapid ketamine response on cortical activity

Ketamine has emerged as a widespread treatment for a variety of psychiatric disorders when used at sub-anesthetic doses, but the neural mechanisms underlying its acute action remain unclear. Here, we identified NMDA receptors containing the 2A subunit (GluN2A) on parvalbumin (PV)-expressing inhibitory interneurons as a pivotal target of low-dose ketamine. Genetically deleting GluN2A receptors globally or selectively from PV interneurons abolished the rapid enhancement of visual cortical responses and gamma-band oscillations by ketamine. Moreover, during the follicular phase of the estrous cycle in female mice, the ketamine response was transiently attenuated along with a concomitant decrease of grin2A mRNA expression within PV interneurons. Thus, GluN2A receptors on PV interneurons mediate the immediate actions of low-dose ketamine treatment, and fluctuations in receptor expression across the estrous cycle may underlie sex-differences in drug efficacy.

Subanesthetic Dose Ketamine in Posttraumatic Stress Disorder: A Role for Reconsolidation During Trauma-Focused Psychotherapy?

Despite efforts to develop more effective therapies, PTSD remains a difficult disorder to treat. Insight into the dynamic nature of memory formation and its required molecular machinery can provide an opportunity to target pathological memories for emotionally arousing events. As memories become labile upon retrieval, novel information can update the strength and course of these consolidated memories. Targeting the process of reconsolidation may offer a relevant approach to attenuate fearful and traumatic memories. Specific molecular mechanisms that are required for reconsolidation of arousing information include an intact functioning of the glutamatergic signaling pathways and, more specifically, the integrity of NMDA receptors. Ketamine, a noncompetitive NMDA-receptor antagonist, is receiving increasing interest for a variety of psychiatric indications. This compound can also be an interesting candidate for targeting emotional memories. We explore whether single intravenous infusion of a subanesthetic dose of ketamine can be considered as a viable augmentation strategy for trauma-focused psychotherapy in patients with PTSD. As a consequence, a systematic approach is needed to assess the pharmacodynamic effects of ketamine in relation to both psychotherapy and its pharmacokinetics prior to its application in patient populations. By using a "question-based drug development plan," we can explore such aspects for novel drugs, and we formulated five additional topics that need to be addressed concerning the psychotherapeutic approach and phase orientation of pharmacological assisted psychotherapy.

Gene-level associations in suicide attempter families show overrepresentation of synaptic genes and genes differentially expressed in brain development

Suicidal behavior (SB) has a complex etiology involving different polygenic and environmental components. Here we used an excess of significant markers (ESM) test to study gene-level associations in previous genome-wide association studies (GWAS) SNP data from a family-based sample, having medically severe suicide attempt (SA) as main outcome in the offspring. In SA without major psychiatric disorders (N = 498), a screening of 5,316 genes across the genome suggested association 17 genes (at fdr < 0.05). Genes RETREG1 (a.k.a. FAM134B), GSN, GNAS, and CACNA1D were particularly robust to different methodological variations. Comparison with the more widely used Multi-marker Analysis of GenoMic Annotation (MAGMA) methods, mainly supported RETREG1, GSN, RNASEH2B, UBE2H, and CACNA1D by using the "mean" model, and ranked 13 of the same genes as ESM among its top-17. Complementing the ESM screen by using MAGMA to analyze 17,899 genes, we observed excess of genes with p < .05 by using the "top" model, and the "mean" model suggested additional genes with genome-wide fdr < 0.25. Overrepresentation analysis of 10 selected gene sets using all genes with p < .05, showed significant results for synaptic genes, genes differentially expressed in brain development and for ~12% of the SA polygenic association genes identified previously in this sample. Exploratory analysis linked some of the ESM top-17 genes to psychotropic drugs and we examined the allelic heterogeneity in the previous SA candidate GRIN2B. This study complemented previous GWAS on SB outcomes, implicating both previous candidate (e.g., GRIN2B and GNAS) and novel genes in SA outcomes, as well as synaptic functions and brain development.

Is Ketamine the Future Clozapine for Depression? A Case Series and Literature Review on Maintenance Ketamine in Treatment-resistant Depression With Suicidal Behavior

Ketamine has shown effectiveness as a rapid-acting antidepressant with antisuicidal effects in terms of reduction of suicidal ideation in the short term. However, the evidence for long-term maintenance ketamine therapy for treatment-resistant depression (TRD) and suicidal behavior is limited. This case series (N=13) highlights the role of adjunctive serial maintenance ketamine infusions in restoring functionality in treatment-resistant unipolar and bipolar (mixed) depression with significant suicide risk and multiple comorbidities, including alcohol dependence. Two cases of TRD achieved functional remission with long-term maintenance ketamine treatment. The first case illustrates the potential synergistic interaction between ketamine and lamotrigine to achieve a sustained antidepressant response in the patient for 7 months. The second case may possibly be the longest reported case of maintenance ketamine therapy, with treatment continuing for 5 years to date. Ketamine treatment showed acute effectiveness in another 7 cases, especially in terms of reduction of suicidal ideation, albeit without significant long-term antidepressant effect. Factors that may contribute to lack of effectiveness of serial ketamine include inadequate mood stabilization in TRD in bipolar spectrum diagnoses, concomitant benzodiazepine use, complex comorbidities, and adverse effects such as significant hypertension and severe dissociation. Future systematic controlled studies are warranted to establish the efficacy and safety profile of long-term ketamine as maintenance therapy for TRD with suicidal behavior.