Ketamine as antidepressant? Current state and future perspectives

Update on the assessment of resistance to antidepressant treatment: Rationale for the Antidepressant Treatment History Form: Short Form-2 (ATHF-SF2)

All definitions of treatment-resistant depression (TRD) require that patients have experienced insufficient benefit from one or more adequate antidepressant trials. Thus, identifying "failed, adequate trials" is key to the assessment of TRD. The Antidepressant Treatment History Form (ATHF) was one of the first and most widely used instruments that provided objective criteria in making these assessments. The original ATHF was updated in 2018 to the ATHF-SF, changing to a checklist format for scoring, and including specific pharmacotherapy, brain stimulation, and psychotherapy interventions as potentially adequate antidepressant treatments. The ATHF-SF2, presented here, is based on the consensus of the ATHF workgroup about the novel interventions introduced since the last revision and which should/should not be considered effective treatments for major depressive episodes. This document describes the rationale for these choices and, for each intervention, the minimal criteria for determining the adequacy of treatment administration. The Supplementary Material that accompanies this article provide the Scoring Checklist, Data Collection Forms (current episode and composite of previous episodes), and Instruction Manual for the ATHF-SF2.

Repurposing General Anesthetic Drugs to Treat Depression: A New Frontier for Anesthesiologists in Neuropsychiatric Care

During the last 100 years, the role of anesthesiologists in psychiatry has focused primarily on facilitating electroconvulsive therapy and mitigating postoperative delirium and other perioperative neurocognitive disorders. The discovery of the rapid and sustained antidepressant properties of ketamine, and early results suggesting that other general anesthetic drugs (including nitrous oxide, propofol, and isoflurane) have antidepressant properties, has positioned anesthesiologists at a new frontier in the treatment of neuropsychiatric disorders. Moreover, shared interest in understanding the biologic underpinnings of anesthetic drugs as psychotropic agents is eroding traditional academic boundaries between anesthesiology and psychiatry. This article presents a brief overview of anesthetic drugs as novel antidepressants and identifies promising future candidates for the treatment of depression. The authors issue a call to action and outline strategies to foster collaborations between anesthesiologists and psychiatrists as they work toward the common goals of repurposing anesthetic drugs as antidepressants and addressing mood disorders in surgical patients.

Effects of a Single Sub-Anesthetic Dose of Ketamine on Postoperative Emotional Responses and Inflammatory Factors in Colorectal Cancer Patients

Objective: To investigate the effect of a single sub-anesthetic dose of ketamine on postoperative anxiety, depression, and inflammatory factors in patients with colorectal cancer. Methods: A total of 104 patients undergoing selective colorectal surgery in our hospital from Jan 2015 to Oct 2017 were included and randomly assigned (1:1:1:1) into a 0.1 mg kg^-1 ketamine group (K1 group), 0.2 mg kg^-1 ketamine group (K2 group), 0.3 mg kg^-1 ketamine group (K3 group), or control group (C group). Corresponding doses of ketamine were given intravenously in the K groups (K1, K2, and K3 groups) 5 min before operation, and the same amount of normal saline was given in the C group. The intravenous analgesia program was identical in the four groups. The patients' emotional reactions (anxiety and depression) were assessed by the Hospital Anxiety and Depression Scale (HAD), the quality of postoperative recovery was evaluated by the Quality of Recovery-40 (QoR-40) questionnaire, and the levels of IL-6, IL-8, and TNF-α in peripheral blood were detected by enzyme-linked immunosorbent assay (ELISA) on the day before operation and within 24, 48, and 72 h post-operation respectively. Pain was estimated by the visual analog scale (VAS), and sedation was assessed with Ramsay score 30 min after extubation. The time points of anesthetic end and extubation were recorded. The complications during anesthesia and recovery such as cough and agitation 30 min after extubation were recorded. Results: The anxiety score (HAD-A) and depression score (HAD-D) of the K3 group were significantly lower than those of the C group post-operation (p < 0.05). The QoR-40 score of the K3 group was significantly higher than that of the C group (p < 0.05). The serum levels of IL-6, IL-8, and TNF-α in the K3 group were significantly lower than those in the C group (p < 0.05 and p < 0.01). There were no significant differences in HAD-A, HAD-D, and QoR-40 scores or serum levels of IL-6, IL-8, and TNF-α between the K1 and K2 groups and the C group. There were no significant differences in VAS pain score or Ramsay sedation score among the four groups 30 min after extubation. There were no significant differences in extubation time, postoperative cough, emergence agitation, or delirium among the four groups. Dizziness, nausea, vomiting, diplopia, or other adverse reactions were not found 30 min after extubation. Conclusion: A single sub-anesthetic dose (0.3 mg kg^-1) of ketamine can significantly improve the postoperative anxiety and depression of colorectal cancer patients and reduce the levels of IL-6, IL-8, and TNF-α.

Low-dose S-ketamine exerts antidepressant-like effects via enhanced hippocampal synaptic plasticity in postpartum depression rats

Rapid antidepressant effects of S-ketamine have repeatedly been confirmed in patients with depression, as well as in chronic unpredictable mild stress (CUMS) animal models. However, the pharmacological study of S-ketamine for anti-postpartum depression has not been considered. In this study, the classical method of reproductive hormone withdrawal was used to construct a rat model of postpartum depression (PPD). Subsequently, the study evaluated the effects of low-dose S-ketamine on behavior and synaptic plasticity, which is related to depression, in the hippocampus of PPD rats. Multiple behavioral tests were used to evaluate depression-like behaviors in PPD models. Synaptic plasticity of the hippocampus can be demonstrated by Western blot, Golgi staining, transmission electron microscopy, and electrophysiological recording. Our study provides insight into the role of low-dose S-ketamine in antidepressant as well as antianxiety and indicates that maintaining synaptic plasticity is a key target for S-ketamine therapy for postpartum depression induced by reproductive hormone withdrawal.

Ketamine for the treatment of mental health and substance use disorders: comprehensive systematic review

BACKGROUND

In the past two decades, subanaesthetic doses of ketamine have been demonstrated to have rapid and sustained antidepressant effects, and accumulating research has demonstrated ketamine's therapeutic effects for a range of psychiatric conditions.

AIMS

In light of these findings surrounding ketamine's psychotherapeutic potential, we systematically review the extant evidence on ketamine's effects in treating mental health disorders.

METHOD

The systematic review protocol was registered in PROSPERO (identifier CRD42019130636). Human studies investigating the therapeutic effects of ketamine in the treatment of mental health disorders were included. Because of the extensive research in depression, bipolar disorder and suicidal ideation, only systematic reviews and meta-analyses were included. We searched Medline and PsycINFO on 21 October 2020. Risk-of-bias analysis was assessed with the Cochrane Risk of Bias tools and A Measurement Tool to Assess Systematic Reviews (AMSTAR) Checklist.

RESULTS

We included 83 published reports in the final review: 33 systematic reviews, 29 randomised controlled trials, two randomised trials without placebo, three non-randomised trials with controls, six open-label trials and ten retrospective reviews. The results were presented via narrative synthesis.

CONCLUSIONS

Systematic reviews and meta-analyses provide support for robust, rapid and transient antidepressant and anti-suicidal effects of ketamine. Evidence for other indications is less robust, but suggests similarly positive and short-lived effects. The conclusions should be interpreted with caution because of the high risk of bias of included studies. Optimal dosing, modes of administration and the most effective forms of adjunctive psychotherapeutic support should be examined further.

Comeback of ketamine: resurfacing facts and dispelling myths

Initially known as CI-581, ketamine was first synthesized in 1962 as a replacement from phencyclidine. It has since been used as an anesthetic and analgesic. In addition, it has bronchodilating, sedative, and amnestic properties, preserving airway reflexes and sympathetic nervous system tone. Since the discovery of ketamine, it has been a major topic of discussion due to controversies regarding its usage in particular sets of patients. In the past 50 years, despite its potential benefits, it is not commonly used because of concerns of "emergence phenomenon," its use as a substance of abuse, and its systemic side effects. Since 2012, three World Health Organization reviews on ketamine have addressed its international control. Researchers have been studying this wonder drug for a decade worldwide. Many myths of ketamine regarding emergence phenomenon and its use in traumatic brain injury and open eye injury have been disproved in recent times. It is becoming popular in pre-hospital settings, critical care, emergency medicine, low-dose acute pain services, and adjuvant in regional anesthesia techniques. This review highlights the current consensus on the various applications of ketamine in the literature.

Efficacy of ketamine therapy in the treatment of depression

BACKGROUND

Severe depressive disorder is among most debilitating condition. Conventional pharmacotherapy usually takes several weeks (usually 4-12 weeks) to improve symptoms. Ketamine is an N-methyl-D aspartate receptor antagonist having rapid action on depressive symptoms.

OBJECTIVES

The effect of subanesthetic dose of ketamine was assessed on depressive and anxiety symptoms. Illness severity and improvement were assessed after treatment with ketamine.

MATERIALS AND METHODS

Twenty-five drug-free/naïve patients of the male sex, with severe depression having no previous history of psychotic disorder, head injury, organic disorder, cardiological problem, or substance abuse were admitted for the study. Assessments were made at baseline and injection ketamine hydrochloride was given at a subanesthetic dose of 0.5 mg/kg intravenous bolus after preparation. Assessments were repeated 1 h after the first dose. Six doses were given over 2 weeks and assessments were repeated. Final assessments were made after 1 month of the last dose.

RESULTS

There was a significant improvement in depression, anxiety, and the severity of illness after 2 weeks and 1 month of the last dose of ketamine. Significant improvement at 1 ^st h of the first dose was seen in depression and anxiety and not for illness severity. There were transient adverse effects observed in some patients which subsided within 1 h.

CONCLUSION

Ketamine has a robust and rapid effect on depression, which was seen immediately after the administration of ketamine and sustained at the end of 1 month.

Brain penetration of ketamine: Intranasal delivery VS parenteral routes of administraion

Ketamine is approved by the FDA to be used as an anesthetic however, recent reports have exhibited its success in the treatment of major depressive disorder (MDD). Studies have suggested that a sub-anesthetic dose produces rapid antidepressant activity providing significant symptomatic relief particularly in patients with a history of treatment resistant depression (TRD). Many reports have been published on the intranasal (IN) efficacy of ketamine in the treatment of depression, however studies that have investigated the effects of the route of administration on drug delivery to the brain appear to be absent in literature. Therefore, in this study, a single dose (15 mg/kg body weight) was administered via different routes of administration [oral (PO), intranasal (IN) and intraperitoneal (IP)] to healthy male Sprague-Dawley rats in order to determine the brain tissue pharmacokinetics of ketamine. A novel validated liquid chromatography-mass spectrometry (LC-MS) method was developed using a fused core column for the determination of ketamine in plasma and brain homogenates. While IP administration resulted in favorable concentrations in the brain and plasma; IN administration, which is supposed to favour drug delivery to the brain, exhibited moderately low drug levels post administration. PO administration produced significantly lower levels due to extensive first-pass metabolism in the liver and intestines. These results have implications for future studies exploring the use of ketamine for the treatment of MDD in order to optimize treatment regimens and suggest that parenteral administration of ketamine should be used in the treatment of depression.

Biological Mechanisms of Cancer-Induced Depression

Patients with cancer are more likely to develop depression than the general population, which negatively impacts their quality of life and prognosis. In order to identify effective antidepressants catered toward cancer patients, the biology of depression in the context of cancer must be well-understood. Many theories have emerged postulating the mechanisms underlying the development of depressive disorder. Here, we review the role inflammation, a hyperactive hypothalamic-pituitary-adrenal (HPA) axis, and glutamate excitotoxicity may play in cancer-induced depression. Hopefully, novel therapeutics targeting these dysregulated pathways may be potent in ameliorating depressive symptoms in the cancer population.

Anaesthesia for electroconvulsive therapy - new tricks for old drugs: a systematic review

OBJECTIVE

The objective of this review is to investigate existing literature in order to delineate whether the use of anaesthesia and timing of seizure induction in a new and optimised way may improve the efficacy of electroconvulsive therapy (ECT).

METHODS

PubMed/MEDLINE was searched for existing literature, last search on 24 June 2015. Relevant clinical studies on human subjects involving choice of anaesthetic, ventilation and bispectral index (BIS) monitoring in the ECT setting were considered. The references of relevant studies were likewise considered.

RESULTS

Propofol yields the shortest seizures, etomidate and ketamine the longest. Etomidate and ketamine+propofol 1 : 1 seems to yield the seizures with best quality. Seizure quality is improved when induction of ECT is delayed until the effect of the anaesthetic has waned - possibly monitored with BIS values. Manual hyperventilation with 100% O2 may increase the pO2/pCO2-ratio, which may be correlated with better seizure quality.

CONCLUSION

Etomidate or a 1 : 1 ketamine and propofol combination may be the best method to achieve general anaesthesia in the ECT setting. There is a need for large randomised prospective studies comparing the effect of methohexital, thiopental, propofol, ketamine, propofol+ketamine 1 : 1 and etomidate in the ECT treatment of major depressed patients. These studies should investigate safety and side effects, and most importantly have antidepressant efficacy and cognitive side effects as outcome measures instead of seizure quality.

Ketamine as a rapid antidepressant: the debate and implications

Ketamine, a synthetic derivative of phencyclidine, is a commonly misused party drug that is restricted in high-income countries because of its addictive potential. Ketamine is also used as an anaesthetic in human and veterinary medicine. In the 1990s, research using ketamine to study the pathophysiology of schizophrenia was terminated owing to ethical concerns. Recently, controversy surrounding the drug has returned, as researchers have demonstrated that intravenous ketamine infusion has a rapid antidepressant effect and have therefore proposed ketamine as a novel antidepressant. This article debates the question of ketamine as an antidepressant, considering the drug's addictive potential, ethical concerns about prescribing a hallucinogen, the evidence base and motives behind ketamine trials.

A Review of the Conceptualisation and Risk Factors Associated with Treatment-Resistant Depression

Major depression does not always remit. Difficult-to-treat depression is thought to contribute to the large disease burden posed by depression. Treatment-resistant depression (TRD) is the conventional term for nonresponse to treatment in individuals with major depression. Indicators of the phenomenon are the poor response rates to antidepressants in clinical practice and the overestimation of the efficacy of antidepressants in medical scientific literature. Current TRD staging models are based on anecdotal evidence without an empirical rationale to rank one treatment strategy above another. Many factors have been associated with TRD such as inflammatory system activation, abnormal neural activity, neurotransmitter dysfunction, melancholic clinical features, bipolarity, and a higher traumatic load. This narrative review provides an overview of this complex clinical problem and discusses the reconceptualization of depression using an illness staging model in line with other medical fields such as oncology.

The Structure-Activity Relationship of a Tetrahydroisoquinoline Class of N-Methyl-d-Aspartate Receptor Modulators that Potentiates GluN2B-Containing N-Methyl-d-Aspartate Receptors

We have identified a series of positive allosteric NMDA receptor (NMDAR) modulators derived from a known class of GluN2C/D-selective tetrahydroisoquinoline analogues that includes CIQ. The prototypical compound of this series contains a single isopropoxy moiety in place of the two methoxy substituents present in CIQ. Modifications of this isopropoxy-containing scaffold led to the identification of analogues with enhanced activity at the GluN2B subunit. We identified molecules that potentiate the response of GluN2B/GluN2C/GluN2D, GluN2B/GluN2C, and GluN2C/GluN2D-containing NMDARs to maximally effective concentrations of agonist. Multiple compounds potentiate the response of NMDARs with submicromolar EC₅₀ values. Analysis of enantiomeric pairs revealed that the S-(-) enantiomer is active at the GluN2B, GluN2C, and/or GluN2D subunits, whereas the R-(+) enantiomer is only active at GluN2C/D subunits. These results provide a starting point for the development of selective positive allosteric modulators for GluN2B-containing receptors.

S-Ketamine Rapidly Reverses Synaptic and Vascular Deficits of Hippocampus in Genetic Animal Model of Depression

BACKGROUND

The neurovascular plasticity of hippocampus is an important theory underlying major depression. Ketamine as a novel glutamatergic antidepressant drug can induce a rapid antidepressant effect within hours. In a mechanistic proof of this concept, we examined whether ketamine leads to an increase in synaptogenesis and vascularization within 24 hours after a single injection in a genetic rat model of depression.

METHODS

Flinders Sensitive Line and Flinders Resistant Line rats were given a single intraperitoneal injection of ketamine (15 mg/kg) or saline. One day later, their behavior was evaluated by a modified forced swim test. Microvessel length was evaluated with global spatial sampling and optical microscopy, whereas the number of asymmetric synapses was quantified through serial section electron microscopy by using physical disector method in the CA1.stratum radiatum area of hippocampus.

RESULTS

The immobility time in the forced swim test among Flinders Sensitive Line rats with ketamine treatment was significantly lower compared with Flinders Sensitive Line rats without treatment. The number of nonperforated and perforated synapses was significantly higher in the Flinders Sensitive Line-ketamine vs the Flinders Sensitive Line-vehicle group; however, ketamine did not induce a significant increase in the number of shaft synapses. Additionally, total length of microvessels was significantly increased 1 day after ketamine treatment in Flinders Sensitive Line rats in the hippocampal subregions, including the CA1.stratum radiatum.

CONCLUSION

Our findings indicate that hippocampal vascularization and synaptogenesis is co-regulated rapidly after ketamine, and microvascular elongation may be a supportive factor for synaptic plasticity and neuronal activity. These findings go hand-in-hand with the behavioral observations, where ketamine acts as a potent antidepressant.

Zinc in the Glutamatergic Theory of Depression

Depression is a serious psychiatric illness that affects millions of people worldwide. Weeks of antidepressant therapy are required to relieve depressive symptoms, and new drugs are still being extensively researched. The latest studies have shown that in depression, there is an imbalance between the main excitatory (glutamatergic) and inhibitory (GABAergic) systems. Administration of antagonists of the glutamatergic system, including zinc, has shown an antidepressant effect in preclinical as well as clinical studies. Zinc inhibits the NMDA receptor via its binding site located on one of its subunits. This is thought to be the main mechanism explaining the antidepressant properties of zinc. In the present review, a link between zinc and the glutamatergic system is discussed in the context of depressive disorder.

Nine traditional Chinese herbal formulas for the treatment of depression: an ethnopharmacology, phytochemistry, and pharmacology review

Depression is a major mental disorder, and is currently recognized as the second-leading cause of disability worldwide. However, the therapeutic effect of antidepressants remains unsatisfactory. For centuries, Chinese herbal formulas (CHFs) have been widely used in the treatment of depression, achieving better therapeutic effects than placebo and having fewer side effects than conventional antidepressants. Here, we review the ethnopharmacology, phytochemistry, and pharmacology studies of nine common CHFs: "banxia houpo" decoction, "chaihu shugansan", "ganmaidazao" decoction, "kaixinsan", "shuganjieyu" capsules, "sinisan", "wuling" capsules, "xiaoyaosan", and "yueju". Eight clinical trials and seven meta-analyses have supported the theory that CHFs are effective treatments for depression, decreasing Hamilton Depression Scale scores and showing few adverse effects. Evidence from 75 preclinical studies has also elucidated the multitarget and multipathway mechanisms underlying the antidepressant effect of the nine CHFs. Decoctions, capsules, and pills all showed antidepressant effects, ranked in descending order of efficacy. According to traditional Chinese medicine theory, these CHFs have flexible compatibility and mainly act by soothing the liver and relieving depression. This review highlights the effective treatment choices and candidate compounds for patients, practitioners, and researchers in the field of traditional Chinese medicine. In summary, the current evidence supports the efficacy of CHFs in the treatment of depression, but additional large-scale randomized controlled clinical trials and sophisticated pharmacology studies should be performed.

Epigenetic Mechanisms of Serotonin Signaling

Histone modifications and DNA methylation represent central dynamic and reversible processes that regulate gene expression and contribute to cellular phenotypes. These epigenetic marks have been shown to play fundamental roles in a diverse set of signaling and behavioral outcomes. Serotonin is a monoamine that regulates numerous physiological responses including those in the central nervous system. The cardinal signal transduction mechanisms via serotonin and its receptors are well established, but fundamental questions regarding complex interactions between the serotonin system and heritable epigenetic modifications that exert control on gene function remain a topic of intense research and debate. This review focuses on recent advances and contributions to our understanding of epigenetic mechanisms of serotonin receptor-dependent signaling, with focus on psychiatric disorders such as schizophrenia and depression.

Rapid-onset antidepressant action of ketamine: potential revolution in understanding and future pharmacologic treatment of depression

WHAT IS KNOWN AND OBJECTIVE

The current pharmacotherapeutic treatment of major depressive disorder (MDD) generally takes weeks to be effective. As the molecular action of these drugs is immediate, the mechanistic basis for this lag is unclear. A drug that has a more rapid onset of action would be a major therapeutic advance and also be a useful comparator to provide valuable mechanistic insight into the disorder and its treatment.

COMMENT

Recent evidence suggests that ketamine produces rapid-onset antidepressant action. Important questions are as follows: is it specific or coincidental to other effects; is there a dose-response relationship; and is the mechanism related to that of current antidepressants. NMDA receptor antagonism is unlikely the explanation for ketamine's antidepressant action.

WHAT IS NEW AND CONCLUSION

It is not an exaggeration to state that the new findings, if validated, might produce a revolution in understanding and treating depressive disorders.

NMDA receptor modulators: an updated patent review (2013-2014)

INTRODUCTION

The NMDA receptor mediates a slow component of excitatory synaptic transmission, and NMDA receptor dysfunction has been implicated in numerous neurological disorders. Thus, interest in developing modulators that are capable of regulating the channel continues to be strong. Recent research has led to the discovery of a number of compounds that hold therapeutic and clinical value. Deeper insight into the NMDA intersubunit interactions and structural motifs gleaned from the recently solved crystal structures of the NMDA receptor should facilitate a deeper understanding of how these compounds modulate the receptor.

AREAS COVERED

This article discusses the known pharmacology of NMDA receptors. A discussion of the patent literature since 2012 is also included, with an emphasis on those that claimed new chemical entities as regulators of the NMDA receptor.

EXPERT OPINION

The number of patents involving novel NMDA receptor modulators suggests a renewed interest in the NMDA receptor as a therapeutic target. Subunit-selective modulators continue to show promise, and the development of new subunit-selective NMDA receptor modulators appears poised for continued growth. Although a modest number of channel blocker patents were published, successful clinical outcomes involving ketamine have led to a resurgent interest in low-affinity channel blockers as therapeutics.

Ketamine: repurposing and redefining a multifaceted drug

This short review will highlight recent clinical and basic research that supports the therapeutic utility of ketamine as a rapid-acting, life-saving antidepressant and a versatile analgesic. After 50 years of use as a dissociative anesthetic and misuse as a street drug, ketamine has re-emerged as a useful off-label agent for ameliorating various types of pain and resistant depression. In addition to its ability to inhibit N-methyl-D-aspartate (NMDA) receptors, the diverse actions of ketamine might involve epigenetic mechanisms such as microRNA regulation. Thus, ketamine is transitioning from being the pharmacologist's nightmare to one of the most interesting developments in the pharmacology of depression and pain.