Safety and Efficacy of Ketamine Without Intubation in the Management of Refractory Seizures: A Case Series

BACKGROUND

Continuous infusion ketamine has demonstrated efficacy in the management of refractory seizures yet does not suppress respiratory drive like other continuous infusion anesthetics (CIAs) used for this indication. The aim of this study is to describe the safety and efficacy of ketamine infusions in patients with refractory seizure without intubation.

METHODS

We analyzed a retrospective cohort of adult patients who were not intubated at the time of initiation of a ketamine infusion for refractory seizures. Seizure onset was determined to be the first clinical seizure or nonconvulsive seizure reported on electroencephalography (EEG) or the start time of EEG for patients with seizures at EEG initiation. Responders were defined as patients with resolution of seizures within 24 h of initiation without the need for intubation or an additional CIA.

RESULTS

A total of 28 patients were analyzed (median age 62 years, 64.3% female, 82.1% African American, 82.1% with structural seizure etiology, and 85.7% focal seizures). Of patients, 78.5% received an initial bolus averaging 0.9 mg/kg, and the majority (89.3%) were initiated on an infusion at 10 μg/kg/minute; median duration was 39.8 h. Maximum infusion rates were 10 μg/kg/minute in 16 patients, 20 μg/kg/minute in seven patients, and 30 μg/kg/minute in five patients. Of patients, 71.4% were assessed to be ketamine responders; six of the eight nonresponders required intubation and an additional CIA. Responders were 80% more likely to have received ketamine 5 or more hours earlier than nonresponders. Hypotension (systolic blood pressure < 90 mmHg) occurred in 31.8% of patients receiving only ketamine, which did not correlate with duration or maximum dose of ketamine; hypertension (systolic blood pressure > 180 mmHg) occurred in 39.3%.

CONCLUSIONS

Ketamine represents a safe and effective treatment option for refractory seizures and has potential to reduce morbidity associated with intubation in a carefully selected patient population. Early initiation may increase the likelihood of success.

Acute Dissociation and Ketamine's Antidepressant and Anti-Suicidal Ideation Effects in a Midazolam-Controlled Trial

OBJECTIVE

We sought to explore relationships of acute dissociative effects of intravenous ketamine with change in depression and suicidal ideation and with plasma metabolite levels in a randomized, midazolam-controlled trial.

METHODS

Data from a completed trial in suicidal, depressed participants (n = 40) randomly assigned to ketamine was used to examine relationships between ketamine treatment-emergent dissociative and psychotomimetic symptoms with pre/post-infusion changes in suicidal ideation and depression severity. Nonparametric correlational statistics were used. These methods were also used to explore associations between dissociative or psychotomimetic symptoms and blood levels of ketamine and metabolites in a subset of participants (n = 28) who provided blood samples immediately post-infusion.

RESULTS

Neither acute dissociative nor psychotomimetic effects of ketamine were associated with changes in suicidal ideation or depressive symptoms from pre- to post-infusion. Norketamine had a trend-level, moderate inverse correlation with dissociative symptoms on Day 1 post-injection (P  = .064; P =.013 removing 1 outlier). Dehydronorketamine correlated with Clinician-Administered Dissociative States Scale scores at 40 minutes (P = .034), 230 minutes (P = .014), and Day 1 (P = .012).

CONCLUSION

We did not find evidence that ketamine's acute, transient dissociative, or psychotomimetic effects are associated with its antidepressant or anti-suicidal ideation actions. The correlation of higher plasma norketamine with lower dissociative symptoms on Day 1 post-treatment suggests dissociation may be more an effect of the parent drug.

Opioid-free anesthesia using a combination of ketamine and dexmedetomidine in patients undergoing laparoscopic cholecystectomy: a randomized controlled trial

BACKGROUND

Opioids administered as bolus doses or continuous infusions are widely used for major and daycare surgeries. Opioid-free anesthesia is multimodal anesthesia and analgesia that does not use opioids, benefiting patients from opioid-related adverse effects. We compared the postoperative analgesic requirements of patients scheduled for elective laparoscopic cholecystectomy under opioid-free and opioid-based anesthesia.

METHODS

Study included 88 patients aged 18-60 years with American Society of Anesthesiologists physical status 1 and 2 who underwent elective laparoscopic cholecystectomy. Participants were randomly divided into two groups with 44 in each. The opioid-free group was administered an intravenous bolus of ketamine and dexmedetomidine, whereas fentanyl was used in opioid group. Primary outcome was to compare the total amount of fentanyl consumed by both groups during 6 h postoperative period. Episodes of postoperative nausea and vomiting (PONV) and vital signs were noted throughout the postoperative period to analyze the secondary outcomes.

RESULTS

Both groups had similar demographic characteristics. The opioid-free group required lesser analgesia within the first 2 h (61.4 ± 17.4 vs. 79.0 ± 19.4 of fentanyl, P < 0.001), which was statistically significant. However, fentanyl consumption was comparable between the groups at 6 h (152 ± 28.2 vs. 164 ± 33.4, P = 0.061). Compared with 4.5% of the participants in the opioid-free group, 34% of those in the opioid-based group developed moderate PONV.

CONCLUSIONS

Opioid-free anesthesia in patients undergoing laparoscopic cholecystectomy reduced the requirement of analgesia in first two-hour postoperative period and was associated with decreased PONV.

A Meta-Analysis of Functional Neuroimaging Studies of Ketamine Administration in Healthy Volunteers

Ketamine administration leads to a psychotomimetic state when taken in large bolus doses, making it a valid model of psychosis. Therefore, understanding ketamine's effects on brain functioning is particularly relevant. This meta-analysis focused on neuroimaging studies that examined ketamine-induced brain activation at rest and during a task. Included are 10 resting-state studies and 23 task-based studies, 9 of which were measuring executive functions. Using a stringent statistical threshold (TFCE <0.05), the results showed increased activity at rest in the dorsal anterior cingulate cortex (ACC), and increased activation of the right Heschl's gyrus during executive tasks, following ketamine administration. Uncorrected results showed increased activation at rest in the right (anterior) insula and the right-fusiform gyrus, as well as increased activation during executive tasks in the rostral ACC. Rest-state studies highlighted alterations in core hubs of the salience network, while task-based studies suggested an impact on task-irrelevant brain regions. Increased activation in the rostral ACC may indicate a failure to deactivate the default mode network during executive tasks following ketamine administration. The results are coherent with alterations found in schizophrenia, which confer external validity to the ketamine model of psychosis. Studies investigating the neural mechanisms of ketamine's antidepressant action are warranted.

Ketamine Improves the Glymphatic Pathway by Reducing the Pyroptosis of Hippocampal Astrocytes in the Chronic Unpredictable Mild Stress Model

Ketamine as a glutamate receptor antagonist has a rapid, potent, and long-lasting antidepressant effect, but its specific mechanism is still not fully understood. Depression is associated with elevated levels of glutamate and astrocyte loss in the brain; the exploration of the relationships between ketamine's antidepressant effect and astrocytes has drawn great attention. Astrocytes and aquaporin 4 (AQP4) are essential components of the glymphatic system, which is a brain-wide perivascular pathway to help transport nutrients to the parenchyma and remove metabolic wastes. In this study, we investigated pyroptosis-associated protein Nlrp3/Caspase-1/Gsdmd-N expression in the hippocampus of mice and the toxic effect of high levels of glutamate on primary astrocytes. On this basis, the protective mechanism of ketamine is explored. A single administration of ketamine (10 mg/kg) remarkably relieved anxious and depressive behaviors in the sucrose preference test, elevated plus maze test, and forced swim test. Meanwhile, ketamine reduced the level of hippocampus Nlrp3 and the expression of its downstream molecules in chronic unpredictable mild stress (CUMS) mice model by western blot and reduced the colocalization of Gfap and Gsdmd by nearly 25% via immunofluorescent staining. Ketamine also increased the Gfap-positive cells and AQP4 expression in the hippocampus of the CUMS mice. More important, ketamine increased the distribution of the fluorescent tracer of CUMS mice. Treatment with 128 mM glutamate in cortical and hippocampus astrocytes increased the level of Nlrp3, and Gsdmd-N, and ketamine alleviated high glutamate-induced pyroptosis-associated proteins. In summary, these results suggest that high glutamate-induced astrocyte pyroptosis through the Nlrp3/Caspase-1/Gsdmd-N pathway which was inhibited by ketamine and ketamine can improve the damaged glymphatic function of the CUMS mice. The present study indicates that inhibiting astrocyte pyroptosis and promoting the glymphatic circulation function are a new mechanism of ketamine's antidepressant effect, and astrocyte pyroptosis may be a new target for other antidepressant medicines.

Electrochemical and biosensor techniques to monitor neurotransmitter changes with depression

Depression is a common mental illness. However, its current treatments, like selective serotonin reuptake inhibitors (SSRIs) and micro-dosing ketamine, are extremely variable between patients and not well understood. Three neurotransmitters: serotonin, histamine, and glutamate, have been proposed to be key mediators of depression. This review focuses on analytical methods to quantify these neurotransmitters to better understand neurological mechanisms of depression and how they are altered during treatment. To quantitatively measure serotonin and histamine, electrochemical techniques such as chronoamperometry and fast-scan cyclic voltammetry (FSCV) have been improved to study how specific molecular targets, like transporters and receptors, change with antidepressants and inflammation. Specifically, these studies show that different SSRIs have unique effects on serotonin reuptake and release. Histamine is normally elevated during stress, and a new inflammation hypothesis of depression links histamine and cytokine release. Electrochemical measurements revealed that stress increases histamine, decreases serotonin, and leads to changes in cytokines, like interleukin-6. Biosensors can also measure non-electroactive neurotransmitters, including glutamate and cytokines. In particular, new genetic sensors have shown how glutamate changes with chronic stress, as well as with ketamine treatment. These techniques have been used to characterize how ketamine changes glutamate and serotonin, and to understand how it is different from SSRIs. This review briefly outlines how these electrochemical techniques work, but primarily highlights how they have been used to understand the mechanisms of depression. Future studies should explore multiplexing techniques and personalized medicine using biomarkers in order to investigate multi-analyte changes to antidepressants.

Brain-derived neurotrophic factor Val66Met and CYP2B6 polymorphisms as predictors for ketamine effectiveness in patients with treatment-resistant depression

BACKGROUND

Converging lines of evidence indicate that ketamine is a rapid antidepressant for individuals with treatment-resistant depression. Hitherto, no reliable a priori predictors of ketamine response have been reported. Pharmacogenetic biomarkers have yielded mixed results regarding potential candidate genes associated with ketamine's biochemistry as reliable predictors of response.

AIMS

No studies have examined the effects of Val66Met and CYP2B6 genotypes on patients receiving repeated infusions of intravenous ketamine.

METHODS

In all, 85 participants with major depressive disorder who had previously received four infusions of intravenous ketamine were recruited to the foregoing study. Buccal swabs were collected and genotype variants across the Val66Met and CYP2B6 genes were analyzed. A repeated measures mixed linear model was used to assess change in depressive symptoms, suicidality, and anxiety, correcting for sex and age. Multiple regression was run to determine whether these genetic markers were associated with treatment efficacy for depressive severity, suicidal ideation, anxiolytic response, and degree of dissociation to intravenous ketamine.

RESULTS

Participants experienced significant overall reductions in depression, suicide, and anxiety. Overall, 25% met the response criteria and 15% met the remission criteria. However, Val66Met and CYP2B6 did not significantly predict changes in symptoms of depression, suicide, anxiety, or average dissociation.

CONCLUSIONS

This study contributes to the growing literature that ketamine efficacy is unlikely to be predicted by single genes, and a pleiotropic approach may likely be necessary for developing reliable predictors of clinical benefits.

Implementation of a ketamine programme for treatment-resistant depression in the public health system: Lessons from the first Australian public hospital clinic

One could argue that we are living through a period of innovation and change in psychiatry unlike that seen before, with repurposed medications emerging as novel treatments. However, despite evidence of enhanced clinical outcomes and potential medium-term savings, delivering these promising interventions is resource-intensive and perceived as difficult in the public sector. Consequently, they are generally only available in the private sector, often at great cost, effectively making them inaccessible to the 'Have Nots'. The arrival of these paradigm-shifting treatments has inadvertently highlighted a growing mental health inequity. The Royal Prince Alfred Hospital's Ketamine Treatment Clinic was the first public-sector ketamine treatment clinic for complex mood disorders in Australia. Based on 3 years' experience establishing, developing and running a public-sector ketamine treatment service, we review the progress, perils and pitfalls for clinicians and health services contemplating establishing a public-sector ketamine treatment service of their own.

Hypersomnia as a predictor of response to intravenous ketamine/intranasal esketamine in treatment resistant depression

BACKGROUND

Sleep disturbances are highly prevalent in depressive episodes and are linked to higher mood severity and suicidal behaviors. Slow wave sleep (SWS) and REM sleep are compromised in depression. Current evidence suggests that rapid antidepressant effects of intravenous (IV) ketamine in patients with treatment-resistant depression (TRD) is mediated by its effects on SWS and REM sleep. Sleep phenotypes may help predict ketamine response.

METHOD

In this observational study, we investigated differences in rates of response among sleep phenotypes defined by QIDS-SR in a cohort of patients with TRD (n = 52) treated with IV ketamine or intranasal (IN) esketamine. Also, we explored a neurovegetative symptoms of atypical depression (NVSAD) phenotype and its association between response and change in QIDS-SR following the treatment with IV ketamine/IN esketamine.

RESULTS

94 % of patients reported sleep difficulties and 62 % reported more than one sleep phenotype with middle and early insomnia being the most prevalent. Individuals with baseline hypersomnia showed higher response rates and more pronounced improvements on their QIDS-SR score. Additionally, 15 % of patients presented with NVSAD phenotype; the majority of whom achieved response and had higher reductions on QIDS-SR. A trend towards faster response was identified for hypersomnia and atypical depression phenotypes.

LIMITATIONS

Observational study design and lack of a placebo group.

CONCLUSIONS

Our data indicate that patients with TRD who have baseline hypersomnia and atypical depression features experienced a more substantial reduction in depressive symptoms and are more likely to achieve response with ketamine/esketamine. This could serve as a future predictor for clinical response.

Comparing sedation protocols for endoscopic retrograde cholangiopancreatography (ERCP): A retrospective study

Background

Endoscopic retrograde cholangiopancreatography (ERCP) is a widely used diagnostic and therapeutic procedure. Effective sedation is crucial to enhance patient comfort and optimize endoscopist performance. Various sedation protocols, including Propofol and Dexmedetomidine (Pro-Dex), Ketamine and Propofol (Keto-Fol), Propofol and Midazolam (Pro-Mid), and Propofol alone, have been utilized during ERCP. This retrospective study aims to compare the safety and efficacy of these four sedation protocols.

Methods

A retrospective analysis was conducted on data from 600 patients who underwent ERCP between 2018 and 2021, with each patient receiving one of the four sedation protocols. Protocol assignment was based on the endoscopist's preference. Data on hemodynamic parameters, sedation level, recovery time, and procedure-related complications were collected.

Results

Baseline data showed no significant differences among the groups pre-procedure. The Pro-Dex group exhibited significantly lower mean total propofol dose, shorter recovery time, and faster achievement of Ramsay Sedation Scale (RSS) score 3-4 compared to the other groups. The Pro-group demonstrated significantly longer hospital stay than the other three groups (median, 4.19 ± 1.1 vs. 3.48 ± 1.2 days in the KP groups, p = 0.042). There were no significant variations in the incidence of respiratory depression, hypotension, or bradycardia among the four groups. Additionally, notable trends were found for hemodynamic measures, total propofol dosage, time to reach the desired level of sedation (as measured by the Ramsay Sedation Scale), and hospital stay based on BMI categories, indicating that higher BMI is linked to more serious outcomes.

Conclusion

Our retrospective study demonstrates that the Pro-Dex protocol offers superior sedation quality, faster recovery, and fewer complications compared to the other protocols during ERCP. However, the incidence of ERCP-related adverse events did not significantly differ among the four sedation protocols. These findings can aid clinicians in selecting the most appropriate sedation protocol for ERCP, considering patient and endoscopist preferences.

Long-term quality of life after repeated ketamine infusions in anxious and nonanxious patients with depression

BACKGROUND

There have been many studies on the benefits of repeated ketamine infusions on patients' depression but few on the impact of ketamine on patients' long-term quality of life (QoL). This study investigated long-term QoL in individuals with depression, both anxious and nonanxious.

METHODS

A total of 107 individuals with a diagnosis of depression were included in the study. The patients were evaluated on Days 0, 13 and 26 and Months 6 and 9, and they received six ketamine infusions over the course of two weeks. The World Health Organization Quality of Life-BREF (WHOQOL-BREF) Scale and the Patient Health Questionnaire-9 (PHQ-9) Scale were used to measure depressive symptoms and QoL. Linear mixed models were used to evaluate depressive symptoms and QoL during ketamine treatment.

RESULTS

A total of 67.2 % of patients were diagnosed with anxious depression. In the long term, there were no significant differences in the time-by-group interactions for general QoL (F = 0.510; P = 0.676), physical QoL (F = 2.092; P = 0.102), psychological QoL (F = 0.102; P = 0.959), social QoL (F = 2.180; P = 0.091), or environmental QoL (F = 1.849; P = 0.139) between the two groups.

LIMITATIONS

The main limitation of this study is its open-label design.

CONCLUSION

The improvement in depression symptoms and QoL following ketamine treatment was not impacted by the presence or absence of anxiety in patients who were depressed prior to treatment. Only occasionally did depressed individuals with anxiety experience a worsening of their quality of life compared to those without anxiety.

Synergistic use of deep TMS therapy with IV ketamine infusions for major depressive disorder: a pilot study

OBJECTIVE

Major Depressive Disorder (MDD) is a pervasive psychiatric condition effecting approximately 21 million adults in the U.S. (8.4%). An estimated 30-60% of patients are resistant to traditional treatment approaches (medications and talk-therapy), alluding to the need for additional options. Two promising treatment modalities include transcranial magnetic stimulation (TMS) and ketamine infusions; both have shown efficacy in standalone studies but have scarcely been investigated synergistically in the same group of participants.

METHOD

In the current study, 169 participants with treatment-resistant MDD received 36 treatments of Deep TMS-only (H1 + H7 protocols), while 66 received 36 treatments of Deep TMS (H1 + H7 protocols) and 6 IV infusions of ketamine over the course of 9 weeks. Depressive symptoms were compared pre- and -post treatment in both conditions using the PHQ-9.

RESULTS

In both treatment groups, depressive symptoms were significantly reduced from pre-to-post and there were no significant differences in response between the TMS + ketamine condition and the TMS-only condition. The TMS + ketamine condition had an 80.30% response rate (53 out of 66) and 43.42% remission rate (28 out of 66) compared to a 76.92% response (130 out of 169) and 39.64% remission (67 out of 16) in the TMS-only condition.

CONCLUSION

These results support the notion that TMS treatments yield high response rates in treatment-resistant cases; however, in this investigation there was no added benefit for including 6 sessions of IV ketamine in conjunction with TMS. Future investigations using randomized-control designs and robust outcome measures are warranted.

The role of mGluR5 on the therapeutic effects of ketamine in Wistar rats

RATIONALE

Ketamine produces dissociative, psychomimetic, anxiolytic, antidepressant, and anesthetic effects in a dose dependent manner. It has a complex mechanism of action that involve alterations in other glutamate receptors. The metabotropic glutamate receptor 5 (mGluR5) has been investigated in relation to the psychotic and anesthetic properties of ketamine, while its role in mediating the therapeutic effects of ketamine remains unknown.

OBJECTIVES

We investigated the role of mGluR5 on the antidepressant, anxiolytic and fear memory-related effects of ketamine in adult male Wistar rats.

METHODS

Two sets of experiments were conducted. We first utilized the positive allosteric modulator CDPPB to investigate how acute mGluR5 activation regulates the therapeutic effects of ketamine (10 mg/kg). We then tested the synergistic antidepressant effect of mGluR5 antagonism and ketamine by combining MTEP with a sub-effective dose of ketamine (1 mg/kg). Behavioral despair, locomotor activity, anxiety-like behavior, and fear memory were respectively assessed in the forced swim test (FST), open field test (OFT), elevated plus maze (EPM), and auditory fear conditioning.

RESULTS

Enhancing mGluR5 activity via CDPPB occluded the antidepressant effect of ketamine without changing locomotor activity. Furthermore, concomitant administration of MTEP and ketamine exhibited a robust synergistic antidepressant effect. The MTEP + ketamine treatment, however, blocked the anxiolytic effect observed by sole administration of MTEP or the low dose ketamine.

CONCLUSIONS

These findings suggest that suppressed mGluR5 activity is required for the antidepressant effects of ketamine. Consequently, the antagonism of mGluR5 enhances the antidepressant effectiveness of low dose ketamine, but eliminates its anxiolytic effects.

Dual-responsive in situ gelling polymer matrix for tunable ketamine general anesthesia in experimental animals

Animal experimentation is a critical part of the drug development process and pharmaceutical research. General anesthesia is one of the most common procedures. Careful administration and dosing of anesthetics ensure animal safety and study success. However, repeated injections are needed to maintain anesthesia, leading to adverse effects. Ketamine, a dissociative anesthetic, is commonly used for inducing anesthesia in animals and suffers from a short half-life requiring repeated dosing. Herein, we report a novel system for controlled anesthesia post-intraperitoneal administration. A polymer solution called "premix" was developed using two stimuli-responsive polymers, Pluronic (PF) and Carbopol (CP). As the premix was mixed with ketamine solution and injected, it underwent in situ gelation, hence controlling ketamine release and anesthesia. The PF and CP concentrations were optimized for the gelation temperature and viscosity upon mixing with the ketamine solution. The optimal premix/ketamine formulation (1.5:1) was liquid at room temperature and gel at physiological conditions with favorable mucoadhesion and rheology. Premix retarded the release of ketamine, translating to tunable anesthesia in vivo. Anesthesia duration and recovery were tunable per ketamine dose with minimal side effects. Therefore, we propose the implementation of PF/CP premix as a vehicle for general anesthesia in animals for optimal duration and effect.

Features of biliary tract diseases in ketamine abusers: a systematic review of case reports

BACKGROUND AND AIMS

Anesthesiologists prefer ketamine for certain surgeries due to its effectiveness as a non-competitive inhibitor of the N-methyl-D-aspartate receptor in the brain. Recently, this agent has also shown promise as an antidepressant. However, ketamine can cause hallucinogenic effects and is sometimes abused as an illicit drug. Ketamine abuse has been associated with liver and bile duct complications. This systematic study aims to better understand cholangiopathy in ketamine abusers by reviewing case reports.

METHODS AND MATERIAL

In this systematic review, a comprehensive literature search was conducted with the terms "biliary tract diseases" and "ketamine". Case reports and case series of adult patients with documented ketamine abuse and reported cholangiopathy or biliary tract disease were included. We extracted the data of relevant information and the results were reported through narrative synthesis and descriptive statistics.

RESULTS

A total of 48 studies were initially identified, and 11 studies were finally included in the review. The mean age of the patients was 25.88 years. Of the 17 patients, 64.7% were men. Symptoms often included abdominal pain, nausea, and vomiting. Most patients were discharged with improved symptoms and liver function. Common bile duct dilation and other findings were observed in imaging results and other diagnostic studies.

CONCLUSION

This review highlights the diverse presentations and diagnostic modalities used in ketamine-induced cholangiography. These patients tend to be young men with deranged liver function tests and abdominal pain, which should be taken into consideration. These patients often require a multidisciplinary approach in their management.

Acute ketamine induces neuronal hyperexcitability and deficits in prepulse inhibition by upregulating IL-6

Acute ketamine administration results in psychotic symptoms similar to those observed in schizophrenia and is regarded as a pharmacological model of schizophrenia. Accumulating evidence suggests that patients with schizophrenia show increased IL-6 levels in the blood and cerebrospinal fluid and that IL-6 levels are associated with the severity of psychotic symptoms. In the present study, we found that a single ketamine exposure led to increased expression of IL-6 and IL-6Rα, decreased dendritic spine density, increased expression and currents of T-type calcium channels, and increased neuron excitability in the hippocampal CA1 area 12 h after exposure. Acute ketamine administration also led to impaired prepulse inhibition (PPI) 12 h after administration. Additionally, we found that the expression of signaling molecules IKKα/β, NF-κB, JAK2, and STAT3 was upregulated 12 h after a single ketamine injection. The decreases in dendritic spine density, the increases in calcium currents and neuron excitability, and the impairments in PPI were ameliorated by blocking IL-6 or IL-6Rα. Our findings show that blocking IL-6 or its receptor may protect hippocampal neurons from hyperexcitability, thereby ameliorating ketamine-induced psychotic effects. Our study provides additional evidence that targeting IL-6 and its receptor is a potential strategy for treating psychotic symptoms in acute ketamine-induced psychosis and schizophrenia.

Ketamine ameliorates activity-based anorexia of adolescent female mice through changes in GluN2B-containing NMDA receptors at postsynaptic cytoplasmic locations of pyramidal neurons and interneurons of medial prefrontal cortex

Anorexia nervosa (AN) is a mental illness with high rates of mortality and relapse, and no approved pharmacotherapy. Using the activity-based anorexia (ABA) model of AN, we previously showed that a single sub-anesthetic intraperitoneal injection of ketamine (30 mg/kg-KET, but not 3 mg/kg-KET), has an immediate and long-lasting effect of reducing anorexia-like behavior among adolescent female mice. We also showed previously that excitatory outflow from medial prefrontal cortex (mPFC) engages hunger-evoked hyperactivity, leading to the ABA condition of severe weight loss. Ketamine is known to target GluN2B-containing NMDARs (NR2B). Might synaptic plasticity involving NR2B in mPFC contribute to ketamine's ameliorative effects? We addressed this question through electron microscopic immunocytochemical quantification of GluN2B at excitatory synapses of pyramidal neurons (PN) and GABAergic interneurons (IN) in mPFC layer 1 of animals that underwent recovery from a second ABA induction (ABA2), 22 days after ketamine injection during the first ABA induction. The 30 mg/kg-KET evoked synaptic plasticity that differed for PN and IN, with changes revolving the cytoplasmic reserve pool of NR2B more than the postsynaptic membrane pool. Those individuals that suppressed hunger-evoked wheel running the most and increased food consumption during recovery from ABA2 the most showed the greatest increase of NR2B at PN and IN excitatory synapses. We hypothesize that 30 mg/kg-KET promotes long-lasting changes in the reserve cytoplasmic pool of NR2B that enables activity-dependent rapid strengthening of mPFC circuits underlying the more adaptive behavior of suppressed running and enhanced food consumption, in turn supporting better weight restoration.

The Use of Ketamine for Malignant and Nonmalignant Chronic Pain in Children: A Review of Current Evidence

Chronic pain in children continues to pose significant challenges. The pharmacological approach most often revolves around trials and errors, expert opinions, and extrapolation of adult study findings. Ketamine is one of the agents used for chronic pain, especially with a neuropathic component. This article aims to provide an overview of its properties and highlight the current evidence for its use in malignant and nonmalignant chronic pain management. A search on the use of ketamine for chronic pain in children up to 18 years of age covering the period from January 1, 2000, to December 14, 2022, was performed through PubMed, Cochrane Library, EBSCO, EBM Review, Wiley, BMJ, Web of Science, Google Scholar, and the Saudi Digital Library. 218 articles were found and 42 underwent full review. Currently, the evidence about ketamine efficacity and safety for chronic pain management is at best of moderate to low quality. The heterogeinity of ketamine infusion protocols and frequent concomitant use of other analgesics make it difficult to draw robust conclusions. The long-term effect of prolonged usage also remains a concern. Nevertheless, with careful monitoring, the drug may be a reasonable choice for malignant and nonmalignant pain management in selected cases, especially for refractory pain not responding to conventional approaches.

Loss of the sustained antidepressant-like effect of (2R,6R)-hydroxynorketamine in NMDA receptor GluN2D subunit knockout mice

Ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, has attracted attention for its acute and sustained antidepressant effects in patients with depression. Hydroxynorketamine (HNK), a metabolite of ketamine, exerts antidepressant effects without exerting ketamine's side effects and has attracted much attention in recent years. However, the detailed pharmacological mechanism of action of HNK remains unclear. We previously showed that the GluN2D NMDA receptor subunit is important for sustained antidepressant-like effects of (R)-ketamine. Therefore, we investigated whether the GluN2D subunit is involved in antidepressant-like effects of (2R,6R)-HNK and (2S,6S)-HNK. Treatment with (2R,6R)-HNK but not (2S,6S)-HNK exerted acute and sustained antidepressant-like effects in the tail-suspension test in wildtype mice. Interestingly, sustained antidepressant-like effects of (2R,6R)-HNK were abolished in GluN2D-knockout mice, whereas acute antidepressant-like effects were maintained in GluN2D-knockout mice. When expression levels of GluN2A and GluN2B subunits were evaluated, a decrease in GluN2B protein expression in the nucleus accumbens was found in stressed wildtype mice but not in stressed GluN2D-knockout mice. These results suggest that the GluN2D subunit and possibly the GluN2B subunit are involved in the sustained antidepressant-like effect of (2R,6R)-HNK.

Efficacy of a combined anti-seizure treatment against cholinergic established status epilepticus following a sarin nerve agent insult in rats

The development of refractory status epilepticus (SE) following sarin intoxication presents a therapeutic challenge. Here, we evaluated the efficacy of delayed combined double or triple treatment in reducing abnormal epileptiform seizure activity (ESA) and the ensuing long-term neuronal insult. SE was induced in rats by exposure to 1.2 LD50 sarin followed by treatment with atropine and TMB4 (TA) 1 min later. Double treatment with ketamine and midazolam or triple treatment with ketamine, midazolam and levetiracetam was administered 30 min post-exposure, and the results were compared to those of single treatment with midazolam alone or triple treatment with ketamine, midazolam, and valproate, which was previously shown to ameliorate this neurological insult. Toxicity and electrocorticogram activity were monitored during the first week, and behavioral evaluations were performed 2 weeks post-exposure, followed by biochemical and immunohistopathological analyses. Both double and triple treatment reduced mortality and enhanced weight recovery compared to TA-only treatment. Triple treatment and, to a lesser extent, double treatment significantly ameliorated the ESA duration. Compared to the TA-only or the TA+ midazolam treatment, both double and triple treatment reduced the sarin-induced increase in the neuroinflammatory marker PGE2 and the brain damage marker TSPO and decreased gliosis, astrocytosis and neuronal damage. Finally, both double and triple treatment prevented a change in behavior, as measured in the open field test. No significant difference was observed between the efficacies of the two triple treatments, and both triple combinations completely prevented brain injury (no differences from the naïve rats). Delayed double and, to a greater extent, triple treatment may serve as an efficacious delayed therapy, preventing brain insult propagation following sarin-induced refractory SE.

Clinical and electrophysiological correlates of hopelessness in the context of suicide risk✰

Hopelessness is a key risk factor for suicide. This analysis explored whether hopelessness indicates a recent suicide crisis state and is linked with magnetoencephalography (MEG) oscillatory power and effective connectivity differences. Change in hopelessness ratings and effective connectivity post-ketamine were also evaluated in a subsample of high-risk individuals to evaluate correlates of dynamic changes over time. Participants (66F;44 M;1 transgender) included individuals with suicide crisis in the last two weeks (High Risk (HR), n = 14), those with past suicide attempt but no recent suicide ideation (SI) (Low Risk (LR), n = 37), clinical controls (CC, n = 33), and healthy volunteers at minimal risk (MinR, n = 27). MEG oscillatory power and clinical hopelessness ratings (via the Beck Hopelessness Scale (BHS)) were evaluated across groups. Dynamic casual modeling (DCM) evaluated connectivity within and between the anterior insula (AI) and anterior cingulate cortex (ACC). A subsample of HR individuals who received ketamine (n = 10) were evaluated at Day 1 post-infusion. The HR group reported the highest levels of hopelessness, even when adjusting for SI. MEG results linked hopelessness with reduced activity across frequency bands in salience network regions, with no group or group-by-interaction effects. Using DCM, the HR group had reduced intrinsic drive from granular Layer IV stellate cells to superficial pyramidal cells in the ACC and AI. In the pilot HR study, reduced hopelessness was linked with increased drive for this same connection post-ketamine. Hopelessness is a possible proxy for suicide risk. Electrophysiological targets for hopelessness include widespread reductions in salience network activity, particularly in the ACC and AI.

Effects of Nostoc commune extract on the cerebral oxidative and neuroinflammatory status in a mice model of schizophrenia

Cyanobacterium Nostoc commune has long been used to alleviate various diseases. This research examines the effects of Nostoc commune extract (NCE) against behavioral disorders, cerebral oxidative stress, and inflammatory damage in the ketamine-induced schizophrenia model. Oral NCE administration (70 and 150 mg/kg/d) is performed after intraperitoneal ketamine injection (20 mg/kg) for 14 consecutive days. The forced swimming and open field tests are used to assess schizophrenia-like behaviors. After the behavioral test, dopamine (DA) level, oxidative stress markers, as well as the interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression are measured in the cerebral cortex. The results show that NCE treatment ameliorates KET-induced anxiety and depressive-like behaviors in OFT and FST, respectively. NCE considerably decreases the malondialdehyde (MDA) and DA levels and IL-6 and TNF-α expressions in mice with schizophrenia-like symptoms. Also, a significant increase is observed in the glutathione (GSH) level and catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GRx) activity in cerebral tissue. The present study shows that NCE treatment effectively improves KET-induced schizophrenia-like behaviors and oxidative and inflammatory damage. Therefore, NCE, via its bioactive constituents, could have strong neuroprotective effects in the schizophrenia-like model.

Ketamine's love story with the heart: A Takotsubo twist

INTRODUCTION

Ketamine is a dissociative anesthetic with N-methyl-d-aspartate and glutamate receptor antagonist properties. It has been the most popular agent to facilitate emergency department procedures for three decades. Considered a safe and effective option for procedural sedation, ketamine has rapid onset, short effective sedation time, and a low risk profile. Ketamine's sympathomimetic effects could theoretically induce stress-related cardiac dysfunction, including cardiomyopathy. A review of the literature demonstrates one prior report of stress (Takotsubo) cardiomyopathy after ketamine sedation.

CASE REPORT

In this case report, we present a case of Takotsubo cardiomyopathy after ketamine sedation for distal radius fracture reduction. The patient presented hemodynamically normal with an unremarkable cardiac ultrasound and progressed to hypoxia from bilateral pulmonary edema, eventually requiring intubation. Inpatient evaluation revealed elevated high sensitivity troponin, non-obstructive coronary arteries on catheterization, and echocardiogram findings of Takotsubo cardiomyopathy. She received operative fixation of her radius fracture by orthopedics and was discharged home on hospital day 9. She had an unremarkable follow up with cardiology but had no echocardiogram to determine full resolution.

CONCLUSION

Although ketamine has robust evidence of safety and efficacy, physicians should be aware of the potential complications of its sympathomimetic effects, from hypertension and tachycardia to overt Takotsubo cardiomyopathy.

Efficacy and Safety of Ketamine to Treat Cancer Pain in Adult Patients: A Systematic Review

CONTEXT

Ketamine is a well-characterized anesthetic agent, and subanesthetic ketamine possesses analgesic effects in both acute and chronic pain.

OBJECTIVES

A systematic review was performed to ascertain the efficacy and safety of ketamine in treating pain for cancer patients.

METHODS

Eight databases were searched from the inception to March 20th, 2023 to obtain randomized controlled trials (RCTs) on ketamine for treating pain in cancer patients. Two reviewers independently screened studies, extracted the data and assessed the risk of bias of included studies; then, meta-analysis was performed by using Revman 5.3 software and Stata 14.0 software.

RESULTS

Thirty-five studies were included, involving 2279 patients with cancer pain. The results of meta-analysis showed that ketamine could significantly reduce pain intensity. Subgroup analysis revealed that, when compared with control group, ketamine decreased markedly visual analogue scale (VAS) scores in two days after the end of treatment with ketamine, and ketamine administrated by patient controlled epidural analgesia (PCEA) was effective. Meanwhile, ketamine could significantly reduce the number of patient-controlled analgesia (PCA) compressions within 24 hours and morphine dosage. Ketamine could not decrease Ramsay sedation score. Additionally, the adverse events significantly decreased in the ketamine group, including nausea and vomiting, constipation, pruritus, lethargy, uroschesis, hallucination, and respiratory depression. In addition, compared with the control group, ketamine could reduce Hamilton depression scale (HAMD) score and relieve depressive symptoms.

CONCLUSION

Ketamine may be used as an effective therapy to relieve cancer pain. However, more rigorously designed RCTs with larger sample sizes are required to verify the above conclusions.