Ketamine and Ketamine Metabolite Pharmacology: Insights into Therapeutic Mechanisms

A Phase 1 Assessment of the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of (2R,6R)-Hydroxynorketamine in Healthy Volunteers

(R,S)-Ketamine (ketamine) is a dissociative anesthetic that also possesses analgesic and antidepressant activity. Undesirable dissociative side effects and misuse potential limit expanded use of ketamine in several mental health disorders despite promising clinical activity and intensifying medical need. (2R,6R)-Hydroxynorketamine (RR-HNK) is a metabolite of ketamine that lacks anesthetic and dissociative activity but maintains antidepressant and analgesic activity in multiple preclinical models. To enable future assessments in selected human indications, we report the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of RR-HNK in a Phase 1 study in healthy volunteers (NCT04711005). A six-level single-ascending dose (SAD) (0.1-4 mg/kg) and a two-level multiple ascending dose (MAD) (1 and 2 mg/kg) study was performed using a 40-minute IV administration emulating the common practice for ketamine administration for depression. Safety assessments showed RR-HNK possessed a minimal adverse event profile and no serious adverse events at all doses examined. Evaluations of dissociation and sedation demonstrated that RR-HNK did not possess anesthetic or dissociative characteristics in the doses examined. RR-HNK PK parameters were measured in both the SAD and MAD studies and exhibited dose-proportional increases in exposure. Quantitative electroencephalography (EEG) measurements collected as a PD parameter based on preclinical findings and ketamine's established effect on gamma-power oscillations demonstrated increases of gamma power in some participants at the lower/mid-range doses examined. Cerebrospinal fluid examination confirmed RR-HNK exposure within the central nervous system (CNS). Collectively, these data demonstrate RR-HNK is well tolerated with an acceptable PK profile and promising PD outcomes to support the progression into Phase 2.

Ketamine and Major Ketamine Metabolites Function as Allosteric Modulators of Opioid Receptors

Ketamine is a glutamate receptor antagonist that was developed over 50 years ago as an anesthetic agent. At subanesthetic doses, ketamine and some metabolites are analgesics and fast-acting antidepressants, presumably through targets other than glutamate receptors. We tested ketamine and its metabolites for activity as allosteric modulators of opioid receptors expressed as recombinant receptors in heterologous systems and with native receptors in rodent brain; signaling was examined by measuring GTP binding, β-arrestin recruitment, MAPK activation, and neurotransmitter release. Although micromolar concentrations of ketamine alone had weak agonist activity at μ opioid receptors, the combination of submicromolar concentrations of ketamine with endogenous opioid peptides produced robust synergistic responses with statistically significant increases in efficacies. All three opioid receptors (μ, δ, and κ) showed synergism with submicromolar concentrations of ketamine and either methionine-enkephalin (Met-enk), leucine-enkephalin (Leu-enk), and/or dynorphin A17 (Dyn A17), albeit the extent of synergy was variable between receptors and peptides. S-ketamine exhibited higher modulatory effects compared with R-ketamine or racemic ketamine, with ∼100% increase in efficacy. Importantly, the ketamine metabolite 6-hydroxynorketamine showed robust allosteric modulatory activity at μ opioid receptors; this metabolite is known to have analgesic and antidepressant activity but does not bind to glutamate receptors. Ketamine enhanced potency and efficacy of Met-enkephalin signaling both in mouse midbrain membranes and in rat ventral tegmental area neurons as determined by electrophysiology recordings in brain slices. Taken together, these findings support the hypothesis that some of the therapeutic effects of ketamine and its metabolites are mediated by directly engaging the endogenous opioid system. SIGNIFICANCE STATEMENT: This study found that ketamine and its major biologically active metabolites function as potent allosteric modulators of μ, δ, and κ opioid receptors, with submicromolar concentrations of these compounds synergizing with endogenous opioid peptides, such as enkephalin and dynorphin. This allosteric activity may contribute to ketamine's therapeutic effectiveness for treating acute and chronic pain and as a fast-acting antidepressant drug.

Prophylactic (R,S)-ketamine and (2S,6S)-HNK decrease fear expression by differentially modulating fear neural ensembles

BACKGROUND

We previously reported that a single injection of (R,S)-ketamine or its metabolite (2S,6S)-hydroxynorketamine (HNK) prior to stress attenuates learned fear. However, whether these drugs attenuate learned fear through divergent or convergent effects on neural activity remains to be determined.

METHODS

129S6/SvEv male mice were injected with saline, (R,S)-ketamine, or (2S,6S)-HNK one week before a 3-shock contextual fear conditioning (CFC) paradigm. Five days later, mice were re-exposed to the aversive context, and euthanized one hour later to quantify active cells. Brains were processed for c-fos immunoreactivity, and neural networks were built with a novel, wide-scale imaging pipeline.

RESULTS

We found that (R,S)-ketamine and (2S,6S)-HNK attenuate learned fear. Fear-related neural activity was altered in: dorsal CA3 following (2S,6S)-HNK; ventral CA3 and CA1, infralimbic (IL) and prelimbic (PL) regions, insular cortex (IC), retrosplenial cortex (RSP), piriform cortex (PIR), nucleus reuniens (RE), and periaqueductal grey (PAG) following both (R,S)-ketamine and (2S,6S)-HNK; and in the paraventricular nucleus of thalamus (PVT) following (R,S)-ketamine. Dorsal CA3 and ventral hippocampus activation correlated with freezing in the (R,S)-ketamine group, and RSP activation correlated with freezing in both (R,S)-ketamine and (2S,6S)-HNK groups. (R,S)-ketamine increased connectivity between cortical and subcortical regions while (2S,6S)-HNK increased connectivity within these regions.

CONCLUSIONS

This work identifies novel nodes in fear networks, involving the RE, PIR, IC, PAG and RSP, that can be targeted with neuromodulatory strategies or pharmaceutical compounds to treat fear-induced disorders. This approach could be used to optimize target engagement and dosing strategies of existing medications.

Ketamine modulates the exploratory dynamics and homebase-related behaviors of adult zebrafish

Anxiety is a protective behavior when animals face aversive conditions, but commonly associated with various neuropsychiatric disorders when exacerbated. Drug repurposing has emerged as a valuable strategy to use existing pharmaceuticals for new therapeutic purposes. Ketamine, traditionally used as an anesthetic, acts as a non-competitive antagonist of the N-methyl-d-aspartate (NMDA) receptor, and evidence has shown potential anxiolytic and antidepressant effects at subanesthetic doses. However, the influence of ketamine on multiple behavioral domains in vertebrates is not completely understood. Here, we evaluated the potential modulatory effect of ketamine on the spatio-temporal exploratory dynamics and homebase-related behaviors in adult zebrafish using the open field test (OFT). Animals were exposed to subanesthetic concentrations of ketamine (0, 2, 20, and 40 mg/L) for 20 min and locomotion- exploration- and homebase-related behaviors were assessed in a single 30-min trial. Our data revealed that ketamine (20 and 40 mg/L) induced hyperlocomotion, as verified by the increased total distance traveled. All concentrations tested elicited circling behavior, a stereotyped-like response which gradually reduced across the periods of test. We also observed modulatory effects of ketamine on the spatio-temporal exploratory pattern, in which the reduced thigmotaxis and homebase activity, associated with the increased average length of trips were suggestive of anxiolytic-like effects. Collectively, our novel findings support the modulatory effects of ketamine on the spatio-temporal exploratory activity, as well as the utility of homebase-related measurements to evaluate the behavioral dynamics of zebrafish.

Differential effects of opioid receptor antagonism on the anti-dyskinetic and anti-parkinsonian effects of sub-anesthetic ketamine treatment in a preclinical model

Sub-anesthetic ketamine treatment has been shown to be an effective therapy for treatment-resistant depression and chronic pain. Our group has previously shown that sub-anesthetic ketamine produces acute anti-parkinsonian, and acute anti-dyskinetic effects in preclinical models of Parkinson's disease (PD). Ketamine is a multifunctional drug and exerts effects through blockade of N-methyl-d-aspartate receptors but also through interaction with the opioid system. In this report, we provide detailed pharmacokinetic rodent data on ketamine and its main metabolites following an intraperitoneal injection, and second, we explore the pharmacodynamic properties of ketamine in a rodent PD model with respect to the opioid system, using naloxone, a pan-opioid receptor antagonist, in unilateral 6-hydroxydopamine-lesioned male rats, treated with 6 mg/kg levodopa (l-DOPA) to establish a model of l-DOPA-induced dyskinesia (LID). As previously reported, we showed that ketamine (20 mg/kg) is highly efficacious in reducing LID and now report that the magnitude of this effect is resistant to naloxone (3 and 5 mg/kg). The higher naloxone dose of 5 mg/kg, however, led to an extension of the time-course of the LID, indicating that opioid receptor activation, while not a prerequisite for the anti-dyskinetic effects of ketamine, still exerts an acute modulatory effect. In contrast to the mild modulatory effect on LID, we found that naloxone added to the anti-parkinsonian activity of ketamine, further reducing the akinetic phenotype. In conclusion, our data show opioid receptor blockade differentially modulates the acute anti-parkinsonian and anti-dyskinetic actions of ketamine, providing novel mechanistic information to support repurposing ketamine for individuals with LID.

Effect of Low-dose Ketamine Infusion on Opioid Consumption in Children Undergoing Open Cardiac Surgery: A Randomized Controlled Double-Blind Study

OBJECTIVE

This study was designed to evaluate the effect of low-dose ketamine infusion on the perioperative consumption of opioids in pediatric open cardiac surgery.

DESIGN

A randomized, controlled, double-blinded single-center study was conducted.

SETTING

The study took place in a tertiary care children's hospital.

PARTICIPANTS

Patients of both sexes aged 2-12 years who underwent cardiac surgery were included.

INTERVENTIONS

Patients in the ketamine group received a bolus of 0.3 mg/kg of ketamine before skin incision followed by continuous intraoperative infusion of 0.25 mg/kg/h and postoperative infusion of 0.1 mg/kg/h for 24 h. Patients in the control groups received volumes of normal saline either bolus or continuous infusion like that of the ketamine group.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the total dose of fentanyl consumed over the first 24 hours postoperatively. Secondary outcomes were intraoperative fentanyl consumption, time to extubation, modified objective pain score, and incidence of vomiting, pruritus, diplopia, or hallucinations. A total of 80 patients were recruited but the final analysis was done on 35 patients in the ketamine group and 34 in the control group. Fentanyl consumption during surgery and in the first 24 hours postoperatively was significantly lower in the ketamine than the control group. Patients in both the ketamine and control groups had similar times to extubation. Modified objective pain scores were significantly lower in the ketamine group than the control group. None of the patients in either group had diplopia or hallucinations.

CONCLUSIONS

Low-dose ketamine infusion in children undergoing open cardiac surgery reduced intra- and postoperative opioid consumption and postoperative pain scores. Moreover, ketamine did not cause diplopia or hallucinations.

Effect of intravenous different drugs on the prevention of restlessness during recovery period of pediatric laparoscopic surgery: a randomized control trial

PURPOSE

To explored the impact of dexmedetomidine and esketamine in mitigating restlessness during the postoperative recovery phase following laparoscopic surgery in children.

METHODS

102 individuals aged 1 to 7 years experiencing laparoscopic surgery were randomly allocated into three groups, each accepting 1 μg/kg of dexmedetomidine, 0.3 mg/kg of esketamine, or saline immediately at the end of carbon dioxide pneumoperitoneum. Emergence agitation (EA) occurrence was assessed by PAED scale and 5-point agitation scale. Pain was judged using Face, Legs, Activity, Cry, and Consolability (FLACC) scale. The recovery time, extubation time, and post-anesthesia care unit (PACU) stay time were recorded for all three groups.

RESULTS

Patients administered 1 μg/kg of dexmedetomidine (8.8%) and individuals given 0.3 mg/kg of esketamine (11.8%) showed lower incidences of emergence agitation compared to those receiving saline (35.5%; P = 0.009). There was no statistically significant difference in the time to discharge from the PACU among the three groups of patients (P > 0.05). The recovery time and extubation time were notably extended in the dexmedetomidine group (40.88 ± 12.95 min, 42.50 ± 13.38 min) when compared to the saline group (32.56 ± 13.05 min, 33.29 ± 11.30 min; P = 0.009, P = 0.010).

CONCLUSION

Following CO2 pneumoperitoneum in pediatric laparoscopic surgeries, the intravenous administration of 1 μg/kg dexmedetomidine or 0.3 mg/kg esketamine effectively lowers EA occurrence without extending PACU time.

Inflammatory cytokines, cortisol, and anhedonia in patients with treatment-resistant depression after consecutive infusions of low-dose esketamine

Anhedonia, defined as a significant loss of interest or pleasure, is one of the core symptoms of treatment- resistant depression (TRD) and is often associated with poor prognosis. This article primarily investigates the changes in anhedonia symptoms, inflammatory markers, and cortisol levels in TRD patients after low-dose esketamine treatments. A total of sixty patients with TRD were enrolled in the clinical study of esketamine. We primarily assessed the severity of depressive symptoms and anhedonia using the Hamilton Rating Scale for Depression (HAMD) and the Snaith-Hamilton Pleasure Scal(SHAPS), respectively, before esketamine treatment and within 24 h after each treatment. Blood specimens were collected before the first treatment and within 1 h after the sixth treatment, measuring the levels of cortisol, interleukin-6(IL-6), interleukin-4(IL-4), and tumor necrosis factor-alpha(TNF-α) in plasma. We found that after six consecutive infusions of low-dose esketamine, patients' depressive symptoms and anhedonia showed improvement. After six treatments, plasma levels of cortisol, IL-6, and TNF-α decreased in patients with TRD, while the anti-inflammatory cytokine IL-4 increased. Multiple linear regression analysis revealed that baseline cortisol levels were correlated with anhedonia, while inflammatory factors showed no significant correlation. Add-on esketamine appears to be a good choice for the treament of the anhedonia in TRD. It has also shown promising effects on altering inflammatory markers in patients with TRD. Moreover, elevated plasma cortisol levels may serve as a potential biomarker for anhedonia in patients with TRD.

Efficacy and safety of esketamine hydrochloride adjunct to sufentanil in non-surgical patients under mechanical ventilation in the ICU (SENSATION trial): protocol for a multicentre, single-blind, randomised controlled trial

INTRODUCTION

Pain is common in patients receiving mechanical ventilation in the intensive care unit (ICU). Intravenous opioids are recommended as first-line therapy for pain management; however, opioids have adverse side effects. Based on low-quality evidence, low-dose ketamine is therefore recommended as an opioid adjunct to reduce opioid consumption. Esketamine is an alternative to ketamine with greater efficacy and fewer side effects. However, evidence on the use of esketamine in patients receiving mechanical ventilation is lacking. This study investigates the efficacy and safety of esketamine as an adjunct to sufentanil for analgesic therapy in non-surgical ICU patients under mechanical ventilation.

METHODS AND ANALYSIS

This ongoing multicentre, single-blind, randomised controlled trial is being conducted at six ICUs in China. 132 non-surgical patients under mechanical ventilation will be randomly assigned to the standard care and S-ketamine groups at a 1:1 ratio. Patients in the standard care group received a minimal dose of sufentanil as the sole analgesic agent. Patients in the S-ketamine group received a minimal dose of sufentanil in addition to an esketamine infusion at a fixed rate of 0.2 mg/kg/hour for analgesia. The primary outcome is mean hourly sufentanil consumption during the treatment period.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Chongqing University Cancer Hospital (CZLS2022067-A). Participants are required to provide informed consent. The results of this trial will be reported in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2200058933.

Psychedelics: From Cave Art to 21st-Century Medicine for Addiction

BACKGROUND

Psychedelic substance use in ritualistic and ceremonial settings dates back as early as 8,500 BCE. Only in recent years, from the mid-20th century, we have seen the re-emergence of psychedelics in a therapeutic setting and more specifically for the treatment of addiction. This article aims to review research over the past 40 years using classic (psilocybin, lysergic acid diethylamide [LSD], dimethyltryptamine [DMT], mescaline) and atypical (ketamine, ibogaine, 5-MeO-DMT, 3,4-methylenedioxymethamphetamine) psychedelics for the treatment of addiction.

SUMMARY

We will start with an overview of the pharmacology and physiological and psychological properties of psychedelic substances from pre-clinical and clinical research. We will then provide an overview of evidence gathered by studies conducted in controlled research environments and naturalistic and ceremonial settings, while we identify the proposed therapeutic mechanisms of each psychedelic substance.

KEY MESSAGES

Classic and atypical psychedelics show promise as therapeutic alternatives for the treatment of addiction, through the improvement of psychological and physiological symptoms of dependence. A more comprehensive understanding of the ancient and present-day knowledge of the therapeutic potential of psychedelics can facilitate hope for psychedelic therapeutics in the treatment of addiction, especially for individuals who have failed other conventional treatment methods.

Ketamine ameliorates post-traumatic social avoidance by erasing the traumatic memory encoded in VTA-innervated BLA engram cells

Erasing traumatic memory during memory reconsolidation is a promising retrieval-extinction strategy for post-traumatic stress disorder (PTSD). Here, we developed an acute social defeat stress (SDS) mouse model with short-term and re-exposure-evoked long-term social avoidance. SDS-associated traumatic memories were identified to be stored in basolateral amygdala (BLA) engram cells. A single intraperitoneal administration of subanesthetic-dose ketamine within, but not beyond, the re-exposure time window significantly alleviates SDS-induced social avoidance, which reduces the activity and quantity of reactivated BLA engram cells. Furthermore, activation or inhibition of dopaminergic projections from the ventral tegmental area to the BLA effectively mimics or blocks the therapeutic effect of re-exposure with ketamine and is dopamine D2 receptor dependent. Single-cell RNA sequencing reveals that re-exposure with ketamine triggered significant changes in memory-related pathways in the BLA. Together, our research advances the understanding of how ketamine mitigates PTSD symptoms and offers promising avenues for developing more effective treatments for trauma-related disorders.

Impact of different doses of esketamine on the incidence of hypotension in propofol-based sedation for colonoscopy: a randomized controlled trial

Background

Hypovolemia is common in colonoscopy due to fasting and bowel preparation, and propofol itself can reduce systemic vascular resistance, resulting in relative hypovolemia. Therefore, hypotension is not a rare event during propofol-based sedation for colonoscopy.

Objectives

Our objective was to explore the efficacy of esketamine as a sedative adjuvant in reducing the incidence of hypotension during colonoscopy.

Design

This was a prospective randomized trial. The trial was registered with the Chinese Clinical Trial Registry (ID: ChiCTR 2100047032).

Methods

We included 100 eligible patients who planned to receive a colonoscopy and randomly divided them into 4 groups with 25 patients in each group, which were propofol 2 mg/kg (Group P), propofol 1 mg/kg with esketamine 0.2 mg/kg (Group E1), propofol 1 mg/kg with esketamine 0.3 mg/kg (Group E2), and propofol 1 mg/kg with esketamine 0.4 mg/kg (Group E3). The hemodynamic and respiratory parameters were documented at various times during the procedure, including the patient's entry into the endoscopic room (T0), the induction of sedation (T1), the insertion of the colonoscope (T2), the removal of the colonoscope (T3), and the awakening of the patient (T4). The primary outcome was the incidence of hypotension. Secondary outcomes were cardiovascular side effects other than hypotension, incidence of hypoxia, cumulative changes in cardiovascular and respiratory parameters, total propofol dosage, anesthesia recovery time, and satisfactory levels of both patients and endoscopists.

Results

The incidence of hypotension in Group E1 (16%), Group E2 (16%), and Group E3 (12%) was significantly lower than in Group P (60%), with p values 0.003, 0.003, and <0.001 respectively. The cumulative changes in diastolic blood pressure and mean arterial pressure in Groups E1, E2, and E3 were significantly higher than in Group P (p = 0.024, p < 0.001, p = 0.006, respectively). Cumulative changes in systolic blood pressure in Group E3 were significantly higher than those in Group P (p = 0.012). The respiratory-related parameters were not statistically significant.

Conclusions

This study showed that the application of 0.4 mg/kg esketamine in propofol-based sedation reduced the incidence of hypotension during colonoscopy while providing satisfactory sedation.

Ketamine and hydroxynorketamine as novel pharmacotherapies for the treatment of Opioid-Use Disorders

Opioid use disorder (OUD) has reached epidemic proportions, with many countries facing high opioid use and related fatalities. Although currently-prescribed medications for OUD (MOUD) are considered life-saving, they inadequately address negative affect and cognitive impairment, resulting in high relapse rates to non-medical opioid use, even years after drug cessation (protracted abstinence). Evidence supports the notion that ketamine, an anesthetic and rapid-acting antidepressant drug, holds promise as a candidate for OUD treatment, including the management of acute withdrawal somatic symptoms, negative affect during protracted opioid abstinence and prevention of re-taking non-medical opioids. In this review, we comprehensively discuss preclinical and clinical research evaluating ketamine and its metabolites as potential novel therapeutic strategies for treating OUDs. We further examine evidence supporting the relevance of the molecular targets of ketamine and its metabolites in relation to their potential effects and therapeutic outcomes in OUDs. Overall, existing evidence demonstrates that ketamine and its metabolites can effectively modulate pathophysiological processes affected in OUD, suggesting their promising therapeutic role in the treatment of OUD and the prevention of return to opioid use during abstinence.

N-methyl-d-aspartate (NMDA) receptor antagonists for treatment of catatonia in adults: Narrative review

OBJECTIVE

While the majority of patients with catatonia fully respond to benzodiazepines or ECT, some have a partial or no response. Benzodiazepines may be contraindicated such as when delirium co-exists. This review discusses the utility of NMDA receptor antagonists as alternatives to benzodiazepines in the treatment of catatonia in adults.

METHODS

A PubMed search adhering to PRISMA guidelines was conducted for articles on NMDA receptor antagonists in catatonia treatment.

RESULTS

Thirty-seven articles, including case reports and case series were identified. Amantadine (27 cases in 13 articles) and memantine (20 cases in 14 articles) were the most commonly reported agents. Amantadine, typically used as monotherapy or adjunctive therapy with benzodiazepines, showed quick responses. Memantine, used alone or with lorazepam, demonstrated rapid responses. A small number of cases (5 cases in 4 articles) reported successful use of ketamine and esketamine, highlighting their potential role in catatonia treatment.

CONCLUSION

Despite limitations, NMDA receptor antagonists may be viable options when the patient is partially or not responsive to benzodiazepine, ECT is not available or may not be well tolerated, there is a concern for co-morbid delirium where benzodiazepines may be contraindicated. Further research is needed.

Ecotoxicological risk assessment of the novel psychoactive substance Esketamine: Emphasis on fish skeletal, behavioral, and vascular development

Novel psychoactive substances (NPS), such as Esketamine (Esket), often contaminate the aquatic ecosystems following human consumption, raising concerns about the residues and potential ecological hazards to non-target organisms. The study used zebrafish as a model organism to investigate the developmental toxicity and ecotoxicological effects of acute Esket exposure. Our findings demonstrate that exposure to Esket significantly affected the early development and angiogenesis of zebrafish embryos/larvae. The mandible length was significantly decreased, and the angles between the pharyngeal arch cartilages were narrowed compared to the control group (all P < 0.05). Additionally, Esket resulted in a decrease of 47.6-89.8 % in the number of neural crest cells (NCC). Transcriptome analysis indicated altered expression of genes associated with cartilage and osteoblast growth. Moreover, Esket significantly inhibited swimming ability in zebrafish larvae and was accompanied by behavioral abnormalities and molecular alterations in the brain. Potential mechanisms underlying Esket-induced behavioral disorders involve neurotransmitter system impairment, abnormal cartilage development and function, aberrant vascular development, as well as perturbations in oxidative stress and apoptosis signaling pathways. Notably, the dysregulation of skeleton development through the bone morphogenetic protein (BMP) signaling pathway is identified as the primary mechanistic behind Esket-induced behavioral disorder. This study enhances our understanding of Esket's ecotoxicology profile and provides a comprehensive assessment of the environmental risks associated with NPS.

Allosteric inhibition of NMDA receptors by low dose ketamine

Ketamine, a general anesthetic, has rapid and sustained antidepressant effects when administered at lower doses. Anesthetic levels of ketamine reduce excitatory transmission by binding deep into the pore of NMDA receptors where it blocks current influx. In contrast, the molecular targets responsible for antidepressant levels of ketamine remain controversial. We used electrophysiology, structure-based mutagenesis, and molecular and kinetic modeling to investigate the effects of ketamine on NMDA receptors across an extended range of concentrations. We report functional and structural evidence that, at nanomolar concentrations, ketamine interacts with membrane-accessible hydrophobic sites on NMDA receptors, which are distinct from the established pore-blocking site. These interactions stabilize receptors in pre-open states and produce an incomplete, voltage- and pH-dependent reduction in receptor gating. Notably, this allosteric inhibitory mechanism spares brief synaptic-like receptor activations and preferentially reduces currents from receptors activated tonically by ambient levels of neurotransmitters. We propose that the hydrophobic sites we describe here account for clinical effects of ketamine not shared by other NMDA receptor open-channel blockers such as memantine and represent promising targets for developing safe and effective neuroactive therapeutics.

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% of 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.

Ketamine and α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid (AMPA) Receptor Potentiation in the Somatosensory Cortex: A Comprehensive Review

Ketamine, a dissociative anesthetic primarily recognized for its antagonism of N-methyl-D-aspartate (NMDA) receptors, has gained significant attention for its rapid antidepressant effects and potential in treating mood disorders. However, recent research indicates that ketamine's influence extends beyond NMDA receptor inhibition, affecting α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and sensory processing. This review delves into ketamine's role in enhancing AMPA receptor function and its implications for sensory processing within the somatosensory cortex. AMPA receptors, essential for fast excitatory neurotransmission and synaptic plasticity, play a key role in sensory perception and integration. By examining preclinical and clinical studies, this review sheds light on how ketamine's modulation of AMPA receptors may improve sensory processing and contribute to its therapeutic effects. Additionally, the review explores the potential for ketamine-based therapies to treat sensory processing disorders and refine current treatment strategies. A deeper understanding of ketamine's complex effects on AMPA receptors and sensory processing could provide valuable insights for developing targeted interventions and advancing clinical applications.

Exploring perinatal ketamine for postpartum depression following cesarean section: A systematic review

The aim of this study was to explore the use of perinatal ketamine to see if it can be used for the reduction of postpartum depression (PPD) following cesarean section (C-section). PubMed, Cochrane, and Web of Science were the primary databases used for this review. Search terms used on January 5, 2024 incorporated "ketamine," "C-section," "postpartum depression," and related synonyms. The criteria for inclusion centered on studies published between January 1, 2008 and January 5, 2024. The final selection of articles was screened based on extraction criteria leaving eight randomized control trials in the final review. The selected data from the studies incorporated sample characteristics, study and population characteristics, and quantitative analyses covering Edinburgh Postpartum Depression Scale (EPDS) scores and depression rates. The Risk of Bias assessment was utilized to gain a deeper understanding of the quality of methodology used by the research studies. The review showed that ketamine can reduce the symptoms of PPD in mothers who have recently undergone C-sections. Some studies showed decreased EPDS scores following the administration of ketamine while two studies also reported no significant differences in PPD following ketamine administration in C-section patients. For example, Ma et al. found that the EPDS score at postpartum day 4 was significantly lower in the ketamine group compared with the control group (p = 0.007) while Yang et al. found that there were no significant differences between the ketamine and control group at 3 days postpartum (p = 0.553). The research from this review suggests that ketamine administration can prevent or decrease the symptoms of PPD, but more research is needed to establish the causal relationship between ketamine dosage and PPD in C-section patients.

Potent and reversible open-channel blocker of NMDA receptor derived from dizocilpine with enhanced membrane-to-channel inhibition

N-methyl-D-aspartate receptors (NMDARs) play a significant role in developing several central nervous system (CNS) disorders. Currently, memantine, used for treating Alzheimer's disease, and ketamine, known for its anesthetic and antidepressant properties, are two clinically used NMDAR open-channel blockers. However, despite extensive research into NMDAR modulators, many have shown either harmful side effects or inadequate effectiveness. For instance, dizocilpine (MK-801) is recognized for its powerful psychomimetic effects due to its high-affinity and nearly irreversible inhibition of the GluN1/GluN2 NMDAR subtypes. Unlike ketamine, memantine and MK-801 also act through a unique, low-affinity "membrane-to-channel inhibition" (MCI). We aimed to develop an open-channel blocker based on MK-801 with distinct inhibitory characteristics from memantine and MK-801. Our novel compound, K2060, demonstrated effective voltage-dependent inhibition in the micromolar range at key NMDAR subtypes, GluN1/GluN2A and GluN1/GluN2B, even in the presence of Mg2+. K2060 showed reversible inhibitory dynamics and a partially trapping open-channel blocking mechanism with a significantly stronger MCI than memantine. Using hippocampal slices, 30 µM K2060 inhibited excitatory postsynaptic currents in CA1 hippocampal neurons by ∼51 %, outperforming 30 µM memantine (∼21 % inhibition). K2060 exhibited No Observed Adverse Effect Level (NOAEL) of 15 mg/kg upon intraperitoneal administration in mice. Administering K2060 at a 10 mg/kg dosage resulted in brain concentrations of approximately 2 µM, with peak concentrations (Tmax) achieved within 15 minutes. Finally, applying K2060 with trimedoxime and atropine in mice exposed to tabun improved treatment outcomes. These results underscore K2060's potential as a therapeutic agent for CNS disorders linked to NMDAR dysfunction.

Ketamine - An Imperfect Wonder Drug?

Ketamine is a potent sedative and dissociative anesthetic agent that has been used clinically for over 50 years since it was first developed in the 1960 s as an alternative to phencyclidine (PCP). When compared to PCP, ketamine exhibited a much lower incidence of severe side effects, including hallucinations, leading to its increased popularity in clinical practice. Ketamine was initially used as an anesthetic agent, especially in emergency medicine and in surgical procedures where rapid induction and recovery was necessary. However, over the last few decades, ketamine was found to have additional clinically useful properties making it effective in the treatment of a variety of other conditions. Presently, ketamine has a wide range of clinical uses beyond anesthesia including management of acute and chronic pain, as well as treatment of psychiatric disorders such as major depression. In addition to various clinical uses, ketamine is also recognized as a common drug of abuse sought for its hallucinogenic and sedative effects. This review focuses on exploring the different clinical and non-clinical uses of ketamine and its overall impact on patient care.

Subanesthetic Dose of Esketamine Improves the Sedative and Analgesic Effects of Dexmedetomidine and Remifentanil in Liposuction Anesthesia: A Prospective, Double-Blinded, Randomized Controlled Trial

Purpose

Esketamine have anesthetic and analgesic properties. This study aimed to observe the enhancing effect of subanesthetic doses of esketamine (0.15-0.3 mg/kg/h) with dexmedetomidine and remifentanil during anesthesia for liposuction surgery.

Patients and Methods

A total of 155 subjects were randomized with a 1:1 ratio to Group E (esketamine-dexmedetomidine/remifentanil, n=78) or Group C (saline-dexmedetomidine/remifentanil group, n=77). The primary outcome was satisfaction of patient and surgical team with the procedure. The secondary outcomes were the postoperative Athens Insomnia Scale (AIS) and Hospital Anxiety and Depression Scale (HADS) scores, hemodynamic and respiratory changes, drug consumption, adverse event rates, and predictors associated with patient satisfaction.

Results

Patient and surgical team satisfaction with the procedure was significantly higher in Group E than in Group C (4.7 ± 0.6 vs 4.2 ± 0.7, P < 0.001; 4.7 ± 0.5 vs 4.4 ± 0.7, P = 0.005). The postoperative AIS (4 [1, 6] vs 5 [2, 9], P = 0.012) and HADS-A (1 [0, 3] vs 2 [0, 6], P = 0.012) scores were significantly lower in Group E than in Group C. Hemodynamic and respiratory parameters were more stable in Group E than in Group C, with the lower opioids consumption of sufentanil (0 [0, 4] vs 5 [2.5, 7.7], P < 0.001) and remifentanil (700 [480, 900] vs 800 [500, 1200], P = 0.023) in Group E compared to Group C. On ordinal logistics regression, postoperative sleep quality (OR, 0.70; 95% CI, 0.62-0.79), anxiety level (OR, 0.77; 95% CI, 0.62-0.95) and recovery time in post-anesthesia care unit (PACU) (OR, 0.69; 95% CI, 0.56-0.98) were identified as significant predictors associated with patient satisfaction.

Conclusion

A subanesthetic dose of esketamine (0.15-0.3 mg/kg/h) as an adjuvant can improves the sedative and analgesic effects of dexmedetomidine and remifentanil during anesthesia for liposuction surgery.

Clinical Trial Registration

ChiCTR2400080363.

Effect of esketamine on serum neurotransmitters in patients with postpartum depression: a randomized controlled trial

BACKGROUND

The development of postpartum depression has been linked to fluctuations in the levels of neurotransmitters in the human body, such as 5-hydroxytryptamine (5-HT), dopamine (DA), noradrenaline (Norepinephrine, NE), and brain derived neurotrophic factor (BDNF). Research has indicated that the antidepressant effect of esketamine are mediated by monoamine transmitters and neurotrophic factors. Therefore, we postulate that intravenous administration of esketamine in patients with postpartum depression may alter the serum concentrations of these neurotransmitters.

METHODS

Three hundred fifteen patients with postpartum depression were selected and divided into two groups based on randomized numerical expression: esketamine (E) group (0. 25 mg/kg esketamine) and control (C) group (a same volume of 0.9% saline), all the drugs were pumped for 40 min. After the end of drug pumping, all patients were continuously observed for 2 h. Changes in serum levels of 5-HT, DA, NE, BDNF were recorded before drug administration and on the 3rd day after drug administration. The scores of Edinburgh Postnatal Depression Scale (EPDS) were calculated before drug administration, and on the 3rd day and on the 30th day after drug administration. Dizziness, headache, nausea, vomiting, drowsiness, and feeling of detachment occurred were recorded within 2 h after drug administration.

RESULTS

Before drug administration, the serum concentrations of 5-HT,DA,BDNF,NE in Group E and Group C were namely (0. 91 ± 0. 19 vs. 0. 98 ± 0. 21, P = 0. 181), (2. 38 ± 0. 35 vs. 2. 32 ± 0. 32, P = 0. 491), (3. 07 ± 0. 89 vs 3. 02 ± 0. 88, P = 0. 828), (39. 79 ± 7. 78 vs 41. 34 ± 10. 03, P = 0. 506). On the third day post-medication, the serum concentrations of 5-HT,DA,BDNF,NE in Group E and Group C were namely (1. 42 ± 0. 35 vs. 0. 96 ± 0. 24, P < 0. 001), (3. 99 ± 0. 17 vs. 2. 41 ± 0. 28, P < 0. 001),(5. 45 ± 0. 81 vs 3. 22 ± 0. 76, P < 0. 001),(44. 36 ± 9. 98 vs 40. 69 ± 11. 75, P = 0. 198). Before medication, the EPDS scores were (16. 15 ± 3. 02 vs 17. 85 ± 3. 89, P = 0. 064). on the third day after medication, the Group E had significantly reduced scores (12. 98 ± 2. 39 vs 16. 73 ± 3. 52, P < 0. 001). On the 30rd day after medication, EPDS scores between the two groups were (16. 34 ± 3. 43 vs 16. 91 ± 4. 02, p = 0. 203). Within 2 h of medication, the rate of adverse events was similar between the two groups.

CONCLUSIONS

Small doses of esketamine can increase the serum concentration of 5-HT,DA,BDNF, and in the short term, decrease EPDS scores, and improve postpartum depressive symptoms.

TRIAL REGISTRATION

Retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR2300078343, 2023/12/05).

The metabolic clock of ketamine abuse in rats by a machine learning model

Ketamine has recently become an anesthetic drug used in human and veterinary clinical medicine for illicit abuse worldwide, but the detection of illicit abuse and inference of time intervals following ketamine abuse are challenging issues in forensic toxicological investigations. Here, we developed methods to estimate time intervals since ketamine use is based on significant metabolite changes in rat serum over time after a single intraperitoneal injection of ketamine, and global metabolomics was quantified by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Thirty-five rats were treated with saline (control) or ketamine at 3 doses (30, 60, and 90 mg/kg), and the serum was collected at 21 time points (0 h to 29 d). Time-dependent rather than dose-dependent features were observed. Thirty-nine potential biomarkers were identified, including ketamine and its metabolites, lipids, serotonin and other molecules, which were used for building a random forest model to estimate time intervals up to 29 days after ketamine treatment. The accuracy of the model was 85.37% in the cross-validation set and 58.33% in the validation set. This study provides further understanding of the time-dependent changes in metabolites induced by ketamine abuse.

Comparison Between Esketamine and Alfentanil for Hysteroscopy: A Prospective, Double-Blind, Randomized Controlled Trial

Purpose

This study aimed to establish the 95% effective dose (ED95) of esketamine in combination with propofol for hysteroscopy and then to evaluate its efficacy and safety profile.

Patients and Methods

This prospective, double-blind, randomized controlled trial consisted of two cohorts. In cohort 1, 45 women aged 18-65 years undergoing hysteroscopy were randomly assigned to either group E (esketamine + propofol) or group A (alfentanil + propofol). Dixon's up-and-down method was used to determine the ED95 of esketamine and alfentanil. In cohort 2, 86 patients were randomized to group E and group A, with the calculated ED95 dose of the study drugs used for induction. The success rate of anesthesia using the ED95% dose, along with parameters related to anesthesia induction, recovery, and adverse events were also recorded.

Results

The ED95 of esketamine was 0.254 mg/kg (95% CI: 0.214-1.004), while that of alfentanil was 9.121 μg/kg (95% CI: 8.479-13.364). The anesthesia success rate was 93.0% in group E and 95.2% in group A (p = 0.664). After resuscitation, both groups achieved a 100% success rate. The induction time was significantly shorter in group E (60.0 [55.0-70.0] s) compared to group A (67.0 [61.0-79.3] s) (p = 0.006). Group E had lower rates of respiratory depression (p < 0.001), hypoxia (p = 0.006), minimum perioperative SpO2 (p = 0.010), and hypotension (p = 0.001). Esketamine had less effect on respiratory rate, heart rate, mean blood pressure, and end-tidal carbon dioxide compared to alfentanil (all p < 0.001). There were no significant differences in postoperative pain between the two groups.

Conclusion

This study determined the ED 95 dose of esketamine for intravenous general anesthesia during hysteroscopy. Esketamine showed less respiratory and hemodynamic depression, as well as fewer adverse effects compared to alfentanil. Esketamine is an ideal anesthetic agent compared to alfentanil for hysteroscopic anesthesia.

Trial Registration

www.chictr.org.cn, (ChiCTR2300077283); registered November 3, 2023.

Opioid-free anesthesia with esketamine-dexmedetomidine versus opioid-based anesthesia with propofol-remifentanil in shoulder arthroscopy: a randomized controlled trial

BACKGROUND

OFA (Opioid-free anesthesia) has the potential to reduce the occurrence of opioid-related adverse events and enhance postoperative recovery. Our research aimed to investigate whether OFA, combining esketamine and dexmedetomidine, could serve as an alternative protocol to traditional OBA (opioid-based anesthesia) in shoulder arthroscopy, particularly in terms of reducing PONV (postoperative nausea and vomiting).

METHODS

A total of 60 patients treated with shoulder arthroscopy from September 2021 to September 2022 were recruited. Patients were randomly assigned to the OBA group (n = 30) and OFA group (n = 30), receiving propofol-remifentanil TIVA (total intravenous anesthesia) and esketamine-dexmedetomidine intravenous anesthesia, respectively. Both groups received ultrasound-guided ISBPB(interscalene brachial plexus block)for postoperative analgesia.

RESULTS

The incidence of PONV on the first postoperative day in the ward (13.3% vs. 40%, P < 0.05) was significantly lower in the OFA group than in the OBA group. Moreover, the severity of PONV was less severe in the OFA group than in the OBA group in PACU (post-anesthesia care unit) (0 [0, 0] vs. 0 [0, 3], P<0.05 ) and in the ward 24 h postoperatively ( 0 [0, 0] vs. 0 [0, 2.25], P<0.05). Additionally, the OFA group experienced a significantly shorter length of stay in the PACU compared to the OBA group (39.4 ± 6.76 min vs. 48.7 ± 7.90 min, P < 0.001).

CONCLUSIONS

Compared to the OBA with propofol-remifentanil, the OFA with esketamine- dexmedetomidine proved to be feasible for shoulder arthroscopy, resulting in a reduced incidence of PONV and a shorter duration of stay in the PACU.

TRIAL REGISTRATION

The Chinese Clinical Trial Registry (No: ChiCTR2100047355), 12/06/2021.

Neuroinflammatory Approach to Surgical Trauma: Biomarkers and Mechanisms of Immune and Neuroendocrine Responses

The severity and invasiveness of clinical outcomes from organic responses to trauma are influenced by individual, surgical, and anesthetic factors. A stress response elicits neuroendocrine and immune reactions that may lead to multi-organ dysfunction. The degree of neuroinflammatory reflex activation from trauma can increase pro-inflammatory cytokine production, leading to endothelial dysfunction, glycocalyx damage, neutrophil activation, and multisystem tissue destruction. A shift in patient treatment towards a neuroinflammatory perspective has prompted a new evaluation protocol for surgical patients, required to understand surgical pathogenesis and its link to chosen anesthetic-surgical methods. The goal of this study is to summarize and disseminate the present knowledge about the mechanisms involved in immune and neuroendocrine responses, focusing on video laparoscopic surgeries. This article outlines various measures cited in the literature aimed at reducing the burden of surgical trauma. It reviews anesthetic drugs, anesthetic techniques, and intensive care procedures that are known to have immunomodulatory effects. The results show a preference for more sensitive inflammatory mediators to tissue trauma serving as care tools, indicators for prognosis, and therapeutic outcomes.

Neurological Effects of Stimulants and Hallucinogens

In this article, we will discuss the history, pharmacodynamics, and neurotoxicity of psychostimulants and hallucinogens. The drugs discussed are widely used and have characteristic toxidromes and potential for neurological injuries with which the practicing clinician should be familiar. Psychostimulants are a class of drugs that includes cocaine, methamphetamine/amphetamines, and cathinones, among others, which produce a crescendoing euphoric high. Seizures, ischemic and hemorrhagic strokes, rhabdomyolysis, and a variety of movement disorders are commonly encountered in this class. Hallucinogens encompass a broad class of drugs, in which the user experiences hallucinations, altered sensorium, distorted perception, and cognitive dysfunction. The experience can be unpredictable and dysphoric, creating a profound sense of anxiety and panic in some cases. Recognizing the associated neurotoxicities and understanding the appropriate management is critical in caring for these patient populations. Several of these agents are not detectable by standard clinical laboratory analysis, making identification and diagnosis an even greater challenge.

Determination of Arylcyclohexylamines in Biological Specimens: Sensors and Sample Pre-Treatment Approaches

Arylcyclohexylamine (ACH) compounds represent a predominant faction within new psychoactive substances. Due to their powerful dissociative effects, they are used in recreational contexts but also in situations of drug-facilitated sexual assault, and therefore, they are a constant target of analysis by forensic experts. In recent years, their consumption has been notably high, especially the use of ketamine, presenting daily challenges for laboratories in the determination of this and other ACH analogues. This review comprises the recent strategies that forensic specialists use to identify and quantify ACH compounds in the laboratory with more traditional analytical techniques and technology, and on the point-of-care testing via sensor technology. The study focuses on analogues of phencyclidine (PCP), ketamine, and eticyclidine, highlighting the consistent need for higher sensitivity in the analysis of various samples collected from real cases and simulations of possible matrices. The review also emphasises the ongoing research to develop more sensitive, quicker, and more capable sensors.

The N-methyl-d-aspartate receptor hypothesis of ketamine's antidepressant action: evidence and controversies

Substantial clinical evidence has unravelled the superior antidepressant efficacy of ketamine: in comparison to traditional antidepressants targeting the monoamine systems, ketamine, as an N-methyl-d-aspartate receptor (NMDAR) antagonist, acts much faster and more potently. Surrounding the antidepressant mechanisms of ketamine, there is ample evidence supporting an NMDAR-antagonism-based hypothesis. However, alternative arguments also exist, mostly derived from the controversial clinical results of other NMDAR inhibitors. In this article, we first summarize the historical development of the NMDAR-centred hypothesis of rapid antidepressants. We then classify different NMDAR inhibitors based on their mechanisms of inhibition and evaluate preclinical as well as clinical evidence of their antidepressant effects. Finally, we critically analyse controversies and arguments surrounding ketamine's NMDAR-dependent and NMDAR-independent antidepressant action. A better understanding of ketamine's molecular targets and antidepressant mechanisms should shed light on the future development of better treatment for depression. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

Lidocaine and Dexamethasone, Ketamine and Dexamethasone, and Dexamethasone Alone in Tonsillectomy Complications

Background

Common complications including stridor, laryngospasm, and bronchospasm are important in patients undergoing general anesthesia. Dexamethasone, lidocaine, and ketamine could have significant roles in reducing these complications. Here we aimed to compare the use of these drugs during tonsillectomy.

Materials and Methods

This study was performed on 100 children that were candidates of tonsillectomy. Patients were divided into 4 groups receiving dexamethasone 0.1 mg/kg and lidocaine 1 mg/kg, ketamine 0.5 mg/kg and dexamethasone 0.1 mg/kg, dexamethasone 0.1 mg/kg, and normal saline after surgical procedures. We evaluated and compared data regarding the duration of anesthesia, oxygenation saturation, blood pressure (systolic and diastolic (SBP and DBP)), re-intubation, laryngospasm, bronchospasm, requiring analgesics after surgeries, recovery stay duration, and nausea and vomiting.

Results

Administration of ketamine and dexamethasone was associated with the lowest pain and lowest need for postoperative analgesic administrations in patients (P = 0.02). Patients that received lidocaine and dexamethasone had the lowest frequencies of airway stimulations (P < 0.001). Evaluations of complications in patients revealed that stridor was significantly lower in patients that received ketamine and dexamethasone (P = 0.01).

Conclusion

Usage of ketamine and dexamethasone was associated with the lowest pain severities and lowest complications. On the other hand, patients that received lidocaine and dexamethasone had the least airway stimulations.

Understanding the Ocular Hypertension Model in Mice Induced by Dexamethasone-21-Acetate - Implications for Glaucoma Research

PURPOSE

This study aimed to assess the effectiveness of monocular and bilateral injections of Dexamethasone-21-acetate (Dex-21-Ac) into the murine fornix twice a week as a glucocorticoid-induced ocular hypertension model and investigated potential systemic side effects.

METHODS

Dex-21-Ac was administered twice weekly in three groups: bilateral injections, monocular injections, and a control group receiving the vehicle solution bilateral. After 21 days, enucleated eyes were examined using immunocytochemistry (ICC), and organ histology was performed.

RESULTS

All groups receiving Dex-21-Ac injections had a significant increase in intraocular pressure (IOP). Monocular injections also resulted in a significant increase in IOP in the fellow eye. The Dex-21-Ac-treated groups showed a bilateral increase in IOP of approximately 8 mmHg, accompanied by elevated expression of alpha smooth muscle actin and fibronectin in the anterior chamber angle. There were no significant changes in weight progression. Hepatic steatosis was observed in all Dex-21-Ac-treated animals, and some suffered from residual neuromuscular blockade under fentanyl anesthesia.

CONCLUSION

Bilateral injections of Dex-21-Ac twice a week lead to a significant increase in daytime IOP and fibrotic changes in the trabecular meshwork. Unilateral application has a significant impact on the fellow eye. Local dexamethasone leads to notable systemic effects independent of changes in animal weight. Considering liver damage and associated influence on metabolization, hepatically eliminated injection anesthetics may lead to overdosing and are not recommended. They should be replaced by inhalation anesthesia.

Potential effect of ketamine in treatment for dextromethorphan use disorder exploding in Japanese young population

In Japan, the landscape of clinical practice for substance use disorder is changing significantly, primarily due to an increase in patients using over-the-counter drugs. A major concern is the rising number of patients misusing dextromethorphan (DXM). These patients with DXM use disorders often have severe trauma-related and mood symptoms, and therefore try to cope with those symptoms by self-medicating with DXM. In this article, we propose that ketamine, which has similar psychopharmacological effects to DXM, may be a useful alternative pharmacological treatment for these patients.

Comparison of anesthesia methods for intra-arterial therapy of patients with acute ischemic stroke: an updated meta-analysis and systematic review

OBJECTIVES

Currently, there remains debate regarding the optimal anesthesia approach for patients undergoing intra-arterial therapy for acute ischemic stroke. Therefore, we conducted a comparative analysis to assess the effects of general anesthesia versus non general anesthesia on patient outcomes.

METHODS

The research methodology entailed comprehensive searches of prominent databases such as the Cochrane Library, PubMed, Scopus, and Web of Science, covering the period from January 1, 2010, to March 1, 2024. Data synthesis employed techniques like risk ratio or standardized mean difference, along with 95% confidence intervals. The study protocol was prospectively registered with PROSPERO (CRD42024523079).

RESULTS

A total of 27 trials and 12,875 patients were included in this study. The findings indicated that opting for non-general anesthesia significantly decreased the risk of in-hospital mortality (RR, 1.98; 95% CI: 1.50 to 2.61; p<0.00001; I2 = 20%), as well as mortality within three months post-procedure (RR, 1.24; 95% CI: 1.15 to 1.34; p<0.00001; I2 = 26%), while also leading to a shorter hospitalization duration (SMD, 0.24; 95% CI: 0.15 to 0.33; p<0.00001; I2 = 44%).

CONCLUSION

Ischemic stroke patients who undergo intra-arterial treatment without general anesthesia have a lower risk of postoperative adverse events and less short-term neurological damage. In routine and non-emergency situations, non-general anesthetic options may be more suitable for intra-arterial treatment, offering greater benefits to patients. In addition to this, the neuroprotective effects of anesthetic drugs should be considered more preoperatively and postoperatively.

Antibiotics, Analgesic Sedatives, and Antiseizure Medications Frequently Used in Critically Ill Neonates: A Narrative Review

Antibiotic, analgesic sedative, and antiseizure medications are among the most commonly used medications in preterm/sick neonates, who are at high risk of nosocomial infections, central nervous system complications, and are exposed to numerous painful/stressful procedures. These severe and potentially life-threatening complications may have serious short- and long-term consequences and should be prevented and/or promptly treated. The reported variability in the medications used in neonates indicates the lack of adequate neonatal studies regarding their effectiveness and safety. Important obstacles contributing to inadequate studies in preterm/sick infants include difficulties in obtaining parental consent, physicians' unwillingness to recruit preterm infants, the off-label use of many medications in neonates, and other scientific and ethical concerns. This review is an update on the use of antimicrobials (antifungals), analgesics (sedatives), and antiseizure medications in neonates, focusing on current evidence or knowledge gaps regarding their pharmacokinetics, indications, safety, dosage, and evidence-based guidelines for their optimal use in neonates. We also address the effects of early antibiotic use on the intestinal microbiome and its association with long-term immune-related diseases, obesity, and neurodevelopment (ND). Recommendations for empirical treatment and the emergence of pathogen resistance to antimicrobials and antifungals are also presented. Finally, future perspectives on the prevention, modification, or reversal of antibiotic resistance are discussed.

Nitric Oxide Donor Sodium Nitroprusside Reduces Racemic Ketamine-But Not Esketamine-Induced Pain Relief

The anesthetic, analgesic and antidepressant drug ketamine produces dissociation with symptoms of psychosis and anxiety, an effect attributed to neuronal nitric oxide depletion following N-methyl-d-aspartate blockade. There is evidence that dissociation induced by racemic ketamine, containing both ketamine enantiomers (S- and R-ketamine) but not esketamine (the S-isomer) is inhibited by nitric oxide (NO) donor sodium nitroprusside (SNP). We tested whether a similar intervention would reduce racemic and esketamine-induced analgesia in a randomized double-blind placebo-controlled trial. Seventeen healthy volunteers were treated with 0.5 μg.kg-1.min-1 SNP or placebo during a 3-h infusion of escalating doses of racemic ketamine (total dose 140 mg) or esketamine (70 mg). Pain pressure threshold (PPT) and arterial blood samples for measurement of S- and R-ketamine and their metabolites, S- and R-norketamine, were obtained. The data were analyzed with a population pharmacokinetic-pharmacodynamic model that incorporated the measured S- and R- ketamine and S- and R-norketamine isomers as input and PPT as output to the model. The potency of the 2 formulations in increasing PPT from baseline by 100% was 0.47 ± 0.12 (median ± standard error of the estimate) nmol/mL for esketamine and 0.62 ± 0.19 nmol/mL for racemic ketamine, reflecting the 52 ± 27% lower analgesic potency of R-ketamine versus S-ketamine. Modeling showed that SNP had no effect on S-ketamine potency but abolished the R-ketamine analgesic effect. Similar observations were made for S- and R-norketamine. Since SNP had no effect on S-ketamine analgesia, we conclude that SNP interacts on R-ketamine nociceptive pathways, possibly similar to its effects on R-ketamine activated dissociation pathways.

The multifaceted perspectives on the regulation of lncRNAs in hepatocellular carcinoma ferroptosis: from bench-to-bedside

Despite being characterized by high malignancy, high morbidity, and low survival rates, the underlying mechanism of hepatocellular carcinoma (HCC) has not been fully elucidated. Ferroptosis, a non-apoptotic form of regulated cell death, possesses distinct morphological, biochemical, and genetic characteristics compared to other types of cell death. Dysregulated actions within the molecular network that regulates ferroptosis have been identified as significant contributors to the progression of HCC. Long non-coding RNAs (lncRNAs) have emerged as influential contributors to diverse cellular processes, regulating gene function and expression through multiple mechanistic pathways. An increasing body of evidence indicates that deregulated lncRNAs are implicated in regulating malignant events such as cell proliferation, growth, invasion, and metabolism by influencing ferroptosis in HCC. Therefore, elucidating the inherent role of ferroptosis and the modulatory functions of lncRNAs on ferroptosis in HCC might promote the development of novel therapeutic interventions for this disease. This review provides a succinct overview of the roles of ferroptosis and ferroptosis-related lncRNAs in HCC progression and treatment, aiming to drive the development of promising therapeutic targets and biomarkers for HCC patients.

Observation on the Analgesic Effect of Different Doses of a Combination of Esketamine and Dexmedetomidine Administered for Percutaneous Endoscopic Transforaminal Discectomy: A Randomized, Double-Blind Controlled Trial

BACKGROUND

Percutaneous endoscopic transforaminal discectomy (PETD) is an effective method for treating lumbar disc herniation, and is typically performed under local anesthesia. However, inadequate analgesia during the procedure remains a concern, prompting the search for a medication that can provide optimal pain control with minimal impact on the respiratory and circulatory systems.

OBJECTIVES

The aim of this study was to observe the effects of different doses of esketamine combined with dexmedetomidine on reducing visual analog scale (VAS) scores during surgical interventions.

METHODS

One hundred two patients who underwent PETD were randomly divided into a control group (group C: normal saline + dexmedetomidine), an E1 group (0.1 mg kg-1 esketamine + dexmedetomidine), and an E2 group (0.2 mg kg-1 esketamine + dexmedetomidine). The primary outcome was the maximum visual analogue scale (VAS) (score: 0 = no pain and 10 = worst pain) at six time points. The secondary outcomes included the Assessment of Alertness/Sedation Scale (OAA/S) score and mean arterial pressure (BP), heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO2) at 11 time points. The incidence of adverse reactions during and 24 h after the operation and patient satisfaction with the anesthesia were also recorded.

RESULTS

Compared with those in group C, the VAS scores of patients in groups E1 and E2 were lower at T6, T7, and T9 (P < 0.05). From T4 to T10, the OAA/S scores of the E1 and E2 groups were both lower than those of group C (P < 0.05), and at the T4-T6 time points, the OAA/S score of the E2 group was lower than that of group E1 (P < 0.05). At T4 and T5, the HR and BP of patients in groups E1 and E2 were greater than those in group C (P < 0.05). Compared with those in group C, the incidences of intraoperative illusion, floating sensation, postoperative dizziness, and hyperalgesia in groups E1 and E2 were significantly greater (P < 0.01). There was no significant difference in patient RR, SpO2, or postoperative satisfaction with anesthesia among the three groups (P > 0.05).

CONCLUSION

The combination of esketamine and dexmedetomidine can reduce VAS scores during certain stages of this type of surgery; it has minimal impact on respiration and circulation. However, this approach is associated with increased incidences of postoperative dizziness and psychiatric side effects, which may also affect patients' compliance with surgical instructions from medical staff. Patient satisfaction was not greater with dexmedetomidine combined with esketamine than with dexmedetomidine alone.

TRIAL REGISTRATION

http://www.chictr.org.cn . Identifier: ChiCTR2300068206. Date of registration: 10 February 2023.

Beyond therapeutic potential: a systematic investigation of ketamine misuse in patients with depressive disorders

Ketamine, a pharmacological agent that acts as an antagonist of the N-methyl-D-aspartate (NMDA) receptor, has garnered considerable interest because of its notable and expeditious antidepressant properties observed in individuals diagnosed with major depressive disorder (MDD) who exhibit resistance to conventional therapeutic interventions. A comprehensive and rigorous systematic review was undertaken to evaluate the prevalence of ketamine abuse undergoing ketamine treatment for depressive disorders. A comprehensive search was conducted across the electronic databases to identify pertinent studies published between 2021 and 2023. The present investigation incorporated a comprehensive range of studies encompassing the abuse or misuse of ketamine, including case reports, observational studies, and clinical trials. Data extraction and quality assessment were conducted in accordance with predetermined criteria. The findings of this systematic review demonstrate the importance of monitoring and addressing ketamine abuse in patients receiving ketamine treatment for depressive disorders like MDD. The wide range of reported prevalence rates highlights the need for standardized criteria and measures for defining and assessing ketamine abuse. This study presents a significant contribution to the field by introducing a novel screening questionnaire and assessment algorithm designed to identify and evaluate ketamine misuse among major depressive disorder (MDD) patients undergoing ketamine treatment. This innovative tool holds the potential to enhance clinical practice by providing healthcare professionals with a standardized approach to promptly detect and address ketamine misuse. The integration of this screening tool into routine care protocols can facilitate more effective monitoring and management of ketamine misuse in this population, ultimately leading to improved patient outcomes and safety.

Dexmedetomidine-ketamine combination versus fentanyl-midazolam for patient sedation during flexible bronchoscopy: a prospective, single-blind, randomized controlled trial

BACKGROUND

Sedation during flexible bronchoscopy (FB) should maintain an adequate respiratory drive, ensure maximum comfort for the patient, and warrant that the objectives of the procedure are achieved. Nevertheless, the optimal sedation method for FB has yet to be established. This study aimed to compare the standard recommended combination of midazolam-fentanyl (MF) with that of dexmedetomidine-ketamine (DK) for patient sedation during FB.

METHODS

Patients subjected to FB were randomly assigned to a DK (n = 25) and an MF group (n = 25). The primary outcome was the rate of critical desaturation events (arterial oxygen saturation < 80% with nasal oxygen supply 2 L/min). Secondary outcomes included sedation depth, hemodynamic complications, adverse events, and patient and bronchoscopist satisfaction.

RESULTS

The incidence rates of critical desaturation events were similar between the two groups (DK: 12% vs. MF: 28%, p = 0.289). DK achieved deeper maximum sedation levels (higher Ramsay - lower Riker scale; p < 0.001) and was associated with longer recovery times (p < 0.001). Both groups had comparable rates of hemodynamic and other complications. Patient satisfaction was similar between the two groups, but bronchoscopist satisfaction was higher with the DK combination (p = 0.033).

CONCLUSION

DK demonstrated a good safety profile in patients subjected to FB and achieved more profound sedation and better bronchoscopist satisfaction than the standard MF combination without increasing the rate of adverse events.

Therapeutic potential of cannabidiol in depression

Major depressive disorder (MDD) is a widespread and debilitating condition affecting a significant portion of the global population. Traditional treatment for MDD has primarily involved drugs that increase brain monoamines by inhibiting their uptake or metabolism, which is the basis for the monoaminergic hypothesis of depression. However, these treatments are only partially effective, with many patients experiencing delayed responses, residual symptoms, or complete non-response, rendering the current view of the hypothesis as reductionist. Cannabidiol (CBD) has shown promising results in preclinical models and human studies. Its mechanism is not well-understood, but may involve monoamine and endocannabinoid signaling, control of neuroinflammation and enhanced neuroplasticity. This chapter will explore CBD's effects in preclinical and clinical studies, its molecular mechanisms, and its potential as a treatment for MDD.

Baseline monocyte count predicts symptom improvement during intravenous ketamine therapy in treatment-resistant depression: a single-arm open-label observational study

Background

Neuroinflammatory processes in depression are associated with treatment resistance to conventional antidepressants. Ketamine is an effective new therapeutic option for treatment-resistant depression (TRD). Its well-established immunomodulatory properties are hypothesized to mediate its antidepressant effect. In this context, higher levels of inflammation may predict a better treatment response. However, conclusive evidence for this hypothesis is lacking. We thus investigated whether standard peripheral inflammatory cell markers and C-reactive protein (CRP) levels could predict symptom improvement during intravenous ketamine therapy in TRD patients.

Methods

27 participants with TRD were treated with six weight-adjusted intravenous ketamine infusions (0.5 mg/kg bodyweight) over three weeks. Baseline assessments included CRP, absolute monocyte count (AMC), and absolute neutrophil count (ANC). Depression severity was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS) at baseline (D1), after the first (D3) and before the last ketamine infusion (D18). Raters were blinded for the baseline laboratory assessments.

Results

13 participants responded to ketamine treatment, and 8 participants partially responded. Baseline AMC showed a strong negative correlation with MADRS change at D3 (r=-0.57, p=0.002) and at D18 (r =-0.48, p=0.010), indicating that a high baseline AMC was associated with greater symptom improvement. A generalized linear model confirmed the association of baseline AMC with symptom improvement during ketamine treatment when additionally accounting for age, sex, and body mass index. Specifically, baseline AMC demonstrated predictive value to discriminate responders and partial responders from non-responders, but lacked discriminative ability between partial responders and responders. Baseline ANC correlated with the MADRS changes at D3 (r=-0.39, p=0.046), while CRP values did not correlate at all.

Conclusions

Our prospective single-arm open-label observational study demonstrated that baseline AMC reliably predicted symptom improvement during intravenous ketamine treatment in TRD patients. AMC could therefore serve as a simple and easily accessible marker for symptom improvement during ketamine therapy in daily clinical practice. Future studies with larger sample sizes and a more detailed longitudinal assessment of AMC subtypes are needed to better understand the specific relationship between monocytes and the neuromodulatory effects of ketamine.

A scientometric analysis of research on the role of NMDA receptor in the treatment of depression

Background

There have been numerous studies on NMDA receptors as therapeutic targets for depression. However, so far, there has been no comprehensive scientometric analysis of this field. Thus, we conducted a scientometric analysis with the aim of better elucidating the research hotspots and future trends in this field.

Methods

Publications on NMDAR in Depression between 2004 and 2023 were retrieved from the Web of Science Core Collection (WoSCC) database. Then, VOSviewer, CiteSpace, Scimago Graphica, and R-bibliometrix-were used for the scientometric analysis and visualization.

Results

5,092 qualified documents were identified to scientometric analysis. In the past 20 years, there has been an upward trend in the number of annual publications. The United States led the world in terms of international collaborations, publications, and citations. 15 main clusters were identified from the co-cited references analysis with notable modularity (Q-value = 0.7628) and silhouette scores (S-value = 0.9171). According to the keyword and co-cited references analysis, treatment-resistant depression ketamine (an NMDAR antagonist), oxidative stress, synaptic plasticity, neuroplasticity related downstream factors like brain-derived neurotrophic factor were the research hotspots in recent years.

Conclusion

As the first scientometric analysis of NMDAR in Depression, this study shed light on the development, trends, and hotspots of research about NMDAR in Depression worldwide. The application and potential mechanisms of ketamine in the treatment of major depressive disorder (MDD) are still a hot research topic at present. However, the side effects of NMDAR antagonist like ketamine have prompted research on new rapid acting antidepressants.

(R)-(-)-Ketamine: The Promise of a Novel Treatment for Psychiatric and Neurological Disorders

NMDA receptor antagonists have potential for therapeutics in neurological and psychiatric diseases, including neurodegenerative diseases, epilepsy, traumatic brain injury, substance abuse disorder (SUD), and major depressive disorder (MDD). (S)-ketamine was the first of a novel class of antidepressants, rapid-acting antidepressants, to be approved for medical use. The stereoisomer, (R)-ketamine (arketamine), is currently under development for treatment-resistant depression (TRD). The compound has demonstrated efficacy in multiple animal models. Two clinical studies disclosed efficacy in TRD and bipolar depression. A study by the drug sponsor recently failed to reach a priori clinical endpoints but post hoc analysis revealed efficacy. The clinical value of (R)-ketamine is supported by experimental data in humans and rodents, showing that it is less sedating, does not produce marked psychotomimetic or dissociative effects, has less abuse potential than (S)-ketamine, and produces efficacy in animal models of a range of neurological and psychiatric disorders. The mechanisms of action of the antidepressant effects of (R)-ketamine are hypothesized to be due to NMDA receptor antagonism and/or non-NMDA receptor mechanisms. We suggest that further clinical experimentation with (R)-ketamine will create novel and improved medicines for some of the neurological and psychiatric disorders that are underserved by current medications.

A combined toxicokinetic and metabolic approach to investigate deschloro-N-ethylketamine exposure in a multidrug user

The use of new psychoactive substances derived from ketamine is rarely reported in France. A chronic GHB, 3-MMC, and methoxetamine consumer presented a loss of consciousness in a chemsex context and was referred to the intensive care unit with a rapid and favorable outcome. To investigate the chemicals responsible for the intoxication, a comprehensive analysis was conducted on the ten plasma samples collected over a 29.5-hour period, urine obtained upon admission, a 2-cm hair strand sample, and a seized crystal. These analyses were performed using liquid chromatography hyphenated to high resolution tandem mass spectrometry operating in targeted and untargeted modes. Additionally, analyses using gas chromatography coupled to mass spectrometry and nuclear magnetic resonance were conducted to probe the composition of the seized crystal. The molecular network-based approach was employed for data processing in non-targeted analyses. It allowed to confirm a multidrug exposure encompassing GHB, methyl-(aminopropyl)benzofuran (MAPB), (aminopropyl)benzofuran (APB), methylmethcathinone, chloromethcathinone, and a new psychoactive substance belonging to the arylcyclohexylamine family namely deschloro-N-ethyl-ketamine (O-PCE). Molecular network analysis facilitated the annotation of 27 O-PCE metabolites, including phase II compounds not previously reported. Plasma kinetics of O-PCE allowed the estimation of the elimination half-life of ∼5 hours. Kinetics of O-PCE metabolites was additionally characterized, possibly useful as surrogate biomarkers of consumption. We also observed marked alterations in lipid metabolism related to poly consumption of drugs. In conclusion, this case report provides a comprehensive analysis of exposure to O-PCE in a multidrug user including kinetic and metabolism data in human.

Research trends and hotspots of ketamine from 2014 to 2023: a bibliometric analysis

Background

Despite this growing interest, there remains a lack of comprehensive and systematic bibliometric analyses of ketamine research. This study aimed to summarize the progress in ketamine research through bibliometric analysis, providing insights into the development and direction of the field.

Methods

Publications related to ketamine were retrieved from the Web of Science Core Collection (WoSCC) database on February 15, 2024. In conducting a comprehensive bibliometric analysis, a variety of bibliographic elements were meticulously collected to map the landscape of research within a specific field.

Results

Between January 1, 2014, and December 31, 2023, a total of 10,328 articles on ketamine research were published across 1,752 academic journals by 45,891 authors from 8,914 institutions in 128 countries. The publication volume has shown a steady increase over this period. The United States of America (USA) and the People's Republic of China lead in both publication and citation counts. The National Institute of Mental Health (NIMH) and Yale University emerge as the most active institutions in this research domain. Carlos Zarate of the NIH National Institute of Mental Health was noted for the highest number of significant publications and received the most co-citations. The analysis revealed key research themes including mechanism of action, adverse events, psychiatric applications, and perioperative implications.

Conclusion

This study provided comprehensive bibliometric and knowledge mapping analysis of the global ketamine research landscape, offering valuable insights into the trends, key contributors, and thematic focus areas within the field. By delineating the evolution of ketamine research, this study aims to guide future scholarly endeavors and enhance our understanding of ketamine's therapeutic potential.

Green Analytical Toxicology procedure for determination of ketamine, its metabolites and analogues in oral fluid samples using dispersive liquid-liquid microextraction (DLLME)

New psychoactive substances (NPS) are often synthesized via small changes in the molecular structure, producing drugs whose effect and potency are not yet fully known. Ketamine is one of the oldest NPS, with therapeutic use in human and veterinary medicine authorized in several countries, being metabolized mainly into norketamine and 6-hydroxy-norketamine. Furthermore, two structural analogues of ketamine have recently been identified, deschloroketamine and 2-fluorodeschloroketamine, marketed as drugs of abuse. To comply with Green Analytical Toxicology (GAT) fundamentals, miniaturized techniques such as dispersive liquid-liquid microextraction (DLLME) were employed to determine toxicants in biological fluids. An analytical method for determining ketamine, its metabolites and its analogues in oral fluid was fully developed and validated by using DLLME and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The extraction parameters were optimized by multivariate analysis, obtaining the best conditions with 200 μL of sample, 100 μL of methanol as dispersive solvent and 50 μL of chloroform as extractor solvent. Linearity was obtained from 10 to 1,000 ng/mL, with limit of detection (LOD) and lower limit of quantification (LLOQ) at 10 ng/mL. Imprecision (% relative standard deviation) and bias (%) were less than 8.2% and 9.5%, respectively. The matrix effect did not exceed 10.6%, and the recovery values varied from 24% to 42%. No matrix interference and good selectivity in the evaluation of 10 different sources of oral fluid and 42 drugs at 500 ng/mL, respectively, were observed. The method was applied in the analysis of 29 authentic oral fluid samples and had its green characteristic evaluated by three different tools: the Green Analytical Procedure Index (GAPI), the Analytical Eco-Scale and the Analytical GREEnness (AGREE) metrics.

Risk of esketamine anesthesia on the emergence delirium in preschool children after minor surgery: a prospective observational clinical study

Emergence delirium (ED) is a common mental complication during recovery from anesthesia. However, studies on the effects of esketamine, an intravenous anesthetic for pediatrics, on ED are still lacking. This study aimed to investigate the effects of a single-dose of esketamine during anesthesia induction on ED after minor surgery in preschool children. A total of 230 children (aged 2-7 years) completed the study. The exposed group (0.46 mg kg-1: average dose of esketamine) was associated with an increased incidence of ED and a higher maximum Pediatric Anesthesia Emergence Delirium score than the non-exposed group. The length of post-anesthesia care unit stay was longer in the exposed group than the non-exposed group. In contrast, extubation time, face, legs, activity, cry, and consolability (FLACC) scores, and the proportions of rescue analgesics were comparable between the two groups. Furthermore, five factors, including preoperative anxiety scores, sevoflurane and propofol compared with sevoflurane alone for anesthesia maintenance, dezocine for postoperative analgesia, FLACC scores, and esketamine exposure, were associated with ED. In conclusion, a near-anesthetic single-dose of esketamine for anesthesia induction may increase the incidence of ED in preschool children after minor surgery. The use of esketamine in preschool children for minor surgery should be noticed during clinical practice.

Ketamine administration causes cognitive impairment by destroying the circulation function of the glymphatic system

BACKGROUND

Ketamine, as a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors, was originally used in general anesthesia. Epidemiological data show that ketamine has become one of the most commonly abused drugs in China. Ketamine administration might cause cognitive impairment; however, its molecular mechanism remains unclear. The glymphatic system is a lymphoid system that plays a key role in metabolic waste removal and cognitive regulation in the central nervous system.

METHODS

Focusing on the glymphatic system, this study evaluated the behavioral performance and circulatory function of the glymphatic system by building a short-term ketamine administration model in mice, and detected the expression levels of the 5-HT2c receptor, ΔFosb, Pten, Akt, and Aqp4 in the hippocampus. Primary astrocytes were cultured to verify the regulatory relationships among related indexes using a 5-HT2c receptor antagonist, a 5-HT2c receptor short interfering RNA (siRNA), and a ΔFosb siRNA.

RESULTS

Ketamine administration induced ΔFosb accumulation by increasing 5-HT2c receptor expression in mouse hippocampal astrocytes and primary astrocytes. ΔFosb acted as a transcription factor to recognize the AATGATTAAT bases in the 5' regulatory region of the Aqp4 gene (-1096 bp to -1087 bp), which inhibited Aqp4 expression, thus causing the circulatory dysfunction of the glymphatic system, leading to cognitive impairment.

CONCLUSIONS

Although this regulatory mechanism does not involve the Pten/Akt pathway, this study revealed a new mechanism of ketamine-induced cognitive impairment in non-neuronal systems, and provided a theoretical basis for the safety of clinical treatment and the effectiveness of withdrawal.

Pharmacotherapeutic advances in fibromyalgia: what's new on the horizon?

INTRODUCTION

This review delves into Fibromyalgia Syndrome (FMS), a chronic pain condition demanding thorough understanding for precise diagnosis and treatment. Yet, a definitive pharmacological solution for FMS remains elusive.

AREAS COVERED

In this article, we systematically analyze various pharmacotherapeutic prospects for FMS treatment, organized into sections based on the stage of drug development and approval. We begin with an overview of FDA-approved drugs, discussing their efficacy in FMS treatment. Next, we delve into other medications currently used for FMS but still undergoing further study, including opioids and muscle relaxants. Further, we evaluate the evidence behind medications that are currently under study, such as cannabinoids and naltrexone. Lastly, we explore new drugs that are in phase II trials. Our research involved a thorough search on PUBMED, Google Scholar, and clinicaltrials.gov. We also discuss the action mechanisms of these drugs and their potential use in specific patient groups.

EXPERT OPINION

A focus on symptom-driven, combination therapy is crucial in managing FMS. There is also a need for ongoing research into drugs that target neuroinflammation, immunomodulation, and the endocannabinoid system. Bridging the gap between benchside research and clinical application is challenging, but it holds potential for more targeted and effective treatment strategies.