Evidence from preclinical and clinical metabolomics studies on the antidepressant effects of ketamine and esketamine

The antidepressant effects of ketamine and esketamine are well-documented. Nonetheless, most of the underlying molecular mechanisms have to be uncovered yet. In the last decade, metabolomics has emerged as a useful means to investigate the metabolic phenotype associated with depression as well as changes induced by antidepressant treatments. This mini-review aims at summarizing the main findings from preclinical and clinical studies that used metabolomics to investigate the metabolic effects of subanesthetic, antidepressant doses of ketamine and esketamine and their relationship with clinical response. Both animal and human studies report alterations in several metabolic pathways - including the tricarboxylic acid cycle, glycolysis, the pentose phosphate pathway, lipid metabolism, amino acid metabolism, the kynurenine pathway, and the urea cycle - following the administration of ketamine or its enantiomers. Although more research is needed to clarify commonalities and differences in molecular mechanisms of action between the racemic compound and its enantiomers, these findings comprehensively support an influence of ketamine and esketamine on mitochondrial and cellular energy production, membrane homeostasis, neurotransmission, and signaling. Metabolomics may thus represent a promising strategy to clarify molecular mechanisms underlying treatment-resistant depression and related markers of clinical response to ketamine and esketamine. This body of preclinical and clinical evidence, if further substantiated, has the potential to guide clinicians towards personalized approaches, contributing to new paradigms in the clinical management of depression.

Ketamine and electroconvulsive therapy for severe depression: A network meta-analysis of efficacy and safety

BACKGROUND

Ketamine, electroconvulsive therapy (ECT), and their combination are effective for treating severe depression, but few large-scale studies have compared these.

METHODS

We searched databases for randomized controlled trials (RCTs) using ketamine, ECT, ketamine + ECT, or placebo for severe depression. Standardized measures were efficacy outcomes. Risk of bias was assessed. Stata and ADDIS were used for network meta-analysis (NMA) comparing efficacy and adverse reactions post-treatment. This study was registered on PROSPERO (CRD42023476740).

RESULTS

17 RCTs with 1370 patients were included. NMA showed ECT and ketamine improved Hamilton Depression Rating Scale (HDRS) versus placebo; other comparisons not significant. Rank probabilities showed highest probability for ECT, followed by ketamine + ECT, ketamine, placebo. No differences in Montgomery-Asberg Depression Rating Scale (MADRS); highest rank probability again for ECT, followed by ketamine + ECT, ketamine, placebo.

CONCLUSIONS

Analysis suggests ECT superior to ketamine and their combination for improving depressive severity, but individualized treatment selection warranted. Higher adverse reactions with ketamine + ECT need further study for optimized combined use.

Enteral Ketamine for Status Epilepticus in Children with Epilepsy

BACKGROUND

Approximately 10% to 20% of children with epilepsy experience status epilepticus (SE), and children with seizure clustering are at higher risk. Ketamine is growing in use for SE. This study examines the efficacy and safety of enteral ketamine in the treatment of convulsive status epilepticus (CSE) characterized by refractory seizure clusters and nonconvulsive status epilepticus (NCSE) in children with epilepsy.

METHODS

Patient charts were reviewed retrospectively. Children with epilepsy aged one to 21 years presenting in SE and treated with enteral ketamine between September 1, 2021 and September 1, 2022 at a pediatric tertiary care center were identified. Resolution or reduction in seizure frequency within 48 hours, clinical presentation, endotracheal intubation, hospitalization duration, side effects, and readmission were assessed.

RESULTS

Nine patients aged two to 21 years were identified. Six patients presented in CSE characterized by recurrent seizures, and three patients presented in NCSE. Five patients had genetic epilepsies, including PCDH19- and MECP2-related epilepsy. Seven patients had resolution or reduction in seizures within 48 hours of ketamine initiation. Two patients were intubated. Hospitalization duration ranged from one to 34 days. Three patients reported side effects. Three patient readmissions with early ketamine treatment had equal or shorter hospitalizations.

CONCLUSIONS

Enteral ketamine may prove an effective, well-tolerated option for treatment of convulsive and nonconvulsive SE in children with epilepsy, including genetic epilepsies, and may prevent intubation and shorten hospitalization time.

Low-dose short infusion ketamine as adjunct to morphine for acute long bone fracture in the emergency department: a randomized controlled trial

BACKGROUND

Ketamine is recognized as an alternative for pain management; however, concerns about emergent adverse reactions have limited its widespread adoption. This study aimed to assess the efficacy of a short infusion of low-dose ketamine (LDK) compared to intravenous morphine (MOR) as adjunctive analgesia for acute long bone fracture pain.

METHODS

This single-blinded, randomized controlled trial was conducted in a single emergency department. Patients with acute long bone fractures and numerical rating scale (NRS) pain scores ≥ 6 following an initial dose of intravenous morphine were assigned to receive either a LDK (0.3 mg/kg) over 15 min or intravenous MOR at a dose of 0.1 mg/kg administered over 5 min. Throughout a 120-min observation period, patients were regularly evaluated for pain level (0-10), side effects, and the need for additional rescue analgesia.

RESULTS

A total of 58 subjects participated, with 27 in the MOR group and 31 in the LDK group. Demographic variables and baseline NRS scores were comparable between the MOR (8.3 ± 1.3) and LDK (8.9 ± 1.2) groups. At 30 min, the LDK group showed a significantly greater mean reduction in NRS scores (3.1 ± 2.03) compared to the MOR group (1.8 ± 1.59) (p = 0.009). Similarly, at 60 min, there were significant differences in mean NRS score reductions (LDK 3.5 ± 2.17; MOR mean reduction = 2.4, ± 1.84) with a p-value of 0.04. No significant differences were observed at other time intervals. The incidence of dizziness was higher in the LDK group at 19.4% (p = 0.026).

CONCLUSION

Short infusion low-dose ketamine, as an adjunct to morphine, is effective in reducing pain during the initial 30 to 60 min and demonstrated comparability to intravenous morphine alone in reducing pain over the subsequent 60 min for acute long bone fractures. However, it was associated with a higher incidence of dizziness.

TRIAL REGISTRATION

NMRR17318438970 (2 May 2018; www.nmrr.gov.my ).

Rapid and sustained antidepressant effects of intravenous ketamine in treatment-resistant major depressive disorder and suicidal ideation: a randomized clinical trial

BACKGROUND

Major depressive disorder (MDD) is the most disabling and burdensome mental disorder, negatively affecting an individual's quality of life and daily functioning. the current study was conducted with the aim of investigating the clinical effects of intravenous ketamine on symptoms of MDD and suicidal ideation.

METHODS

The current randomized clinical trial was carried out on 64 patients diagnosed with treatment-resistant major depressive disorder between April and August 2022. The participants were randomly assigned to two groups: the intervention group received a dose of 0.5 mg/kg of ketamine, while the control group received normal saline. The Montgomery-Asberg Depression Scale and Beck's Suicidal Ideation Scale were utilized to assess depression and suicidal ideation, respectively.

RESULTS

One hour after the administration of ketamine treatment, there was a notable and significant improvement in both depression symptoms (35.16 ± 8.13 vs. 14.90 ± 10.09) and suicidal ideation (6.74 ± 6.67 vs. 0.42 ± 1.52). Moreover, there were statistically significant differences in depression scores between the two groups at one hour, four hours, one day, three days, one week, one month, and two months after the administration of ketamine (p-value < 0.001). However, ketamine recipients frequently experienced side effects such as increased heart rate, headache, dizziness, and dissociative syndrome symptoms.

CONCLUSION

The observed rapid onset of action and sustained effect demonstrate the potential of ketamine to provide relief from depressive symptoms in a shorter timeframe compared to traditional treatment approaches. These findings contribute to the growing body of evidence supporting the use of ketamine as a valuable therapeutic option for patients with treatment-resistant depression.

IRCT REGISTRATION

IRCT registration number: IRCT20210806052096N1; IRCT URL: https://www.irct.ir/trial/62243 ; Ethical code: IR.ZUMS.REC.1400.150; Registration date: 2022-04-09.

The impact of scheduling ketamine as an internationally controlled substance on anaesthesia care in Sub-Saharan Africa: a case study and key informant interviews

BACKGROUND

Access to anaesthesia and surgical care is a major problem for people living in Sub-Saharan Africa. In this region, ketamine is critical for the provision of anaesthesia care. However, efforts to control ketamine internationally as a controlled substance may significantly impact its accessibility. This research therefore aims to estimate the importance of ketamine for anaesthesia and surgical care in Sub-Saharan Africa and assess the potential impact on access to ketamine if it were to be scheduled.

METHODS

This research is a mixed-methods study, comprising of a cross-sectional survey at the hospital level in Rwanda, and key informant interviews with experts on anaesthesia care in Sub-Saharan Africa. Data on availability of four anaesthetic agents were collected from hospitals (n = 54) in Rwanda. Semi-structured interviews with 10 key informants were conducted, collecting information on the importance of ketamine, the potential impact of scheduling ketamine internationally, and opinions on misuse of ketamine. Interviews were transcribed verbatim and analysed using a thematic analysis approach.

RESULTS

The survey conducted in Rwanda found that availability of ketamine and propofol was comparable at around 80%, while thiopental and inhalational agents were available at only about half of the hospitals. Significant barriers impeding access to anaesthesia care were identified, including a general lack of attention given to the specialty by governments, a shortage of anaesthesiologists and migration of trained anaesthesiologists, and a scarcity of medicines and equipment. Ketamine was described as critical for the provision of anaesthesia care as a consequence of these barriers. Misuse of ketamine was not believed to be an issue by the informants.

CONCLUSION

Ketamine is critical for the provision of anaesthesia care in Sub-Saharan Africa, and its scheduling would have a significantly negative impact on its availability for anaesthesia care.

Substance specific EEG patterns in mice undergoing slow anesthesia induction

The exact mechanisms and the neural circuits involved in anesthesia induced unconsciousness are still not fully understood. To elucidate them valid animal models are necessary. Since the most commonly used species in neuroscience are mice, we established a murine model for commonly used anesthetics/sedatives and evaluated the epidural electroencephalographic (EEG) patterns during slow anesthesia induction and emergence. Forty-four mice underwent surgery in which we inserted a central venous catheter and implanted nine intracranial electrodes above the prefrontal, motor, sensory, and visual cortex. After at least one week of recovery, mice were anesthetized either by inhalational sevoflurane or intravenous propofol, ketamine, or dexmedetomidine. We evaluated the loss and return of righting reflex (LORR/RORR) and recorded the electrocorticogram. For spectral analysis we focused on the prefrontal and visual cortex. In addition to analyzing the power spectral density at specific time points we evaluated the changes in the spectral power distribution longitudinally. The median time to LORR after start anesthesia ranged from 1080 [1st quartile: 960; 3rd quartile: 1080]s under sevoflurane anesthesia to 1541 [1455; 1890]s with ketamine. Around LORR sevoflurane as well as propofol induced a decrease in the theta/alpha band and an increase in the beta/gamma band. Dexmedetomidine infusion resulted in a shift towards lower frequencies with an increase in the delta range. Ketamine induced stronger activity in the higher frequencies. Our results showed substance-specific changes in EEG patterns during slow anesthesia induction. These patterns were partially identical to previous observations in humans, but also included significant differences, especially in the low frequencies. Our study emphasizes strengths and limitations of murine models in neuroscience and provides an important basis for future studies investigating complex neurophysiological mechanisms.

Ketamine-induced prevention of SD-associated late infarct progression in experimental ischemia

Spreading depolarizations (SDs) occur frequently in patients with malignant hemispheric stroke. In animal-based experiments, SDs have been shown to cause secondary neuronal damage and infarct expansion during the initial period of infarct progression. In contrast, the influence of SDs during the delayed period is not well characterized yet. Here, we analyzed the impact of SDs in the delayed phase after cerebral ischemia and the potential protective effect of ketamine. Focal ischemia was induced by distal occlusion of the left middle cerebral artery in C57BL6/J mice. 24 h after occlusion, SDs were measured using electrocorticography and laser-speckle imaging in three different study groups: control group without SD induction, SD induction with potassium chloride, and SD induction with potassium chloride and ketamine administration. Infarct progression was evaluated by sequential MRI scans. 24 h after occlusion, we observed spontaneous SDs with a rate of 0.33 SDs/hour which increased during potassium chloride application (3.37 SDs/hour). The analysis of the neurovascular coupling revealed prolonged hypoemic and hyperemic responses in this group. Stroke volume increased even 24 h after stroke onset in the SD-group. Ketamine treatment caused a lesser pronounced hypoemic response and prevented infarct growth in the delayed phase after experimental ischemia. Induction of SDs with potassium chloride was significantly associated with stroke progression even 24 h after stroke onset. Therefore, SD might be a significant contributor to delayed stroke progression. Ketamine might be a possible drug to prevent SD-induced delayed stroke progression.

Predicting non-response to ketamine for depression: An exploratory symptom-level analysis of real-world data among military veterans

Ketamine helps some patients with treatment resistant depression (TRD), but reliable methods for predicting which patients will, or will not, respond to treatment are lacking. Herein, we aim to inform prediction models of non-response to ketamine/esketamine in adults with TRD. This is a retrospective analysis of PHQ-9 item response data from 120 patients with TRD who received repeated doses of intravenous racemic ketamine or intranasal eskatamine in a real-world clinic. Regression models were fit to patients' symptom trajectories, showing that all symptoms improved on average, but depressed mood improved relatively faster than low energy. Principal component analysis revealed a first principal component (PC) representing overall treatment response, and a second PC that reflects variance across affective versus somatic symptom subdomains. We then trained logistic regression classifiers to predict overall response (improvement on PC1) better than chance using patients' baseline symptoms alone. Finally, by parametrically adjusting the classifier decision thresholds, we identified optimal models for predicting non-response with a negative predictive value of over 96 %, while retaining a specificity of 22 %. Thus, we could identify 22 % of patients who would not respond based purely on their baseline symptoms. This approach could inform rational treatment recommendations to avoid additional treatment failures.

Electrical stimulation of the ventral tegmental area restores consciousness from sevoflurane-, dexmedetomidine-, and fentanyl-induced unconsciousness in rats

BACKGROUND

Dopaminergic neurons in the ventral tegmental area (VTA) are crucially involved in regulating arousal, making them a potential target for reversing general anesthesia. Electrical deep brain stimulation (DBS) of the VTA restores consciousness in animals anesthetized with drugs that primarily enhance GABAA receptors. However, it is unknown if VTA DBS restores consciousness in animals anesthetized with drugs that target other receptors.

OBJECTIVE

To evaluate the efficacy of VTA DBS in restoring consciousness after exposure to four anesthetics with distinct receptor targets.

METHODS

Sixteen adult Sprague-Dawley rats (8 female, 8 male) with bipolar electrodes implanted in the VTA were exposed to dexmedetomidine, fentanyl, ketamine, or sevoflurane to produce loss of righting, a proxy for unconsciousness. After receiving the dopamine D1 receptor antagonist, SCH-23390, or saline (vehicle), DBS was initiated at 30 μA and increased by 10 μA until reaching a maximum of 100 μA. The current that evoked behavioral arousal and restored righting was recorded for each anesthetic and compared across drug (saline/SCH-23390) condition. Electroencephalogram, heart rate and pulse oximetry were recorded continuously.

RESULTS

VTA DBS restored righting after sevoflurane, dexmedetomidine, and fentanyl-induced unconsciousness, but not ketamine-induced unconsciousness. D1 receptor antagonism diminished the efficacy of VTA stimulation following sevoflurane and fentanyl, but not dexmedetomidine.

CONCLUSIONS

Electrical DBS of the VTA restores consciousness in animals anesthetized with mechanistically distinct drugs, excluding ketamine. The involvement of the D1 receptor in mediating this effect is anesthetic-specific.

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

BACKGROUND

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

METHODS

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

RESULTS

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

LIMITATIONS

The study included two Cohorts with different dosing regimes.

CONCLUSIONS

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

Ketamine-based Sedation Use in Mechanically Ventilated Critically Ill Patients with COVID-19: A Multicenter Cohort Study

Backgrounds

Ketamine possesses analgesia, anti-inflammation, anticonvulsant, and neuroprotection properties. However, the evidence that supports its use in mechanically ventilated critically ill patients with COVID-19 is insufficient. The study's goal was to assess ketamine's effectiveness and safety in critically ill, mechanically ventilated (MV) patients with COVID-19.

Methods

Adult critically ill patients with COVID-19 were included in a multicenter retrospective-prospective cohort study. Patients admitted between March 1, 2020, and July 31, 2021, to five ICUs in Saudi Arabia were included. Eligible patients who required MV within 24 hours of ICU admission were divided into two sub-cohort groups based on their use of ketamine (Control vs. Ketamine). The primary outcome was the length of stay (LOS) in the hospital. P/F ratio differences, lactic acid normalization, MV duration, and mortality were considered secondary outcomes. Propensity score (PS) matching was used (1:2 ratio) based on the selected criteria.

Results

In total, 1,130 patients met the eligibility criteria. Among these, 1036 patients (91.7 %) were in the control group, whereas 94 patients (8.3 %) received ketamine. The total number of patients after PS matching, was 264 patients, including 88 patients (33.3 %) who received ketamine. The ketamine group's LOS was significantly lower (beta coefficient (95 % CI): -0.26 (-0.45, -0.07), P = 0.008). Furthermore, the PaO2/FiO2 ratio significantly improved 24 hours after the start of ketamine treatment compared to the pre-treatment period (6 hours) (124.9 (92.1, 184.5) vs. 106 (73.1, 129.3; P = 0.002). Additionally, the ketamine group had a substantially shorter mean time for lactic acid normalization (beta coefficient (95 % CI): -1.55 (-2.42, -0.69), P 0.01). However, there were no significant differences in the duration of MV or mortality.

Conclusions

Ketamine-based sedation was associated with lower hospital LOS and faster lactic acid normalization but no mortality benefits in critically ill patients with COVID-19. Thus, larger prospective studies are recommended to assess the safety and effectiveness of ketamine as a sedative in critically ill adult patients.

A mean-field model of gamma-frequency oscillations in networks of excitatory and inhibitory neurons

Gamma oscillations are widely seen in the cerebral cortex in different states of the wake-sleep cycle and are thought to play a role in sensory processing and cognition. Here, we study the emergence of gamma oscillations at two levels, in networks of spiking neurons, and a mean-field model. At the network level, we consider two different mechanisms to generate gamma oscillations and show that they are best seen if one takes into account the synaptic delay between neurons. At the mean-field level, we show that, by introducing delays, the mean-field can also produce gamma oscillations. The mean-field matches the mean activity of excitatory and inhibitory populations of the spiking network, as well as their oscillation frequencies, for both mechanisms. This mean-field model of gamma oscillations should be a useful tool to investigate large-scale interactions through gamma oscillations in the brain.

Change in neurocognitive functioning in patients with treatment-resistant depression with serial intravenous ketamine infusions: The Bio-K multicenter trial

This nonrandomized, multicenter, open-label clinical trial explored the impact of intravenous (IV) ketamine on cognitive function in adults (n = 74) with treatment-resistant depression (TRD). Patients received three IV ketamine infusions during the acute phase and, if remitted, four additional infusions in the continuation phase (Mayo site). Cognitive assessments using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) were conducted at baseline, end of the acute phase, and end of the continuation phase (Mayo site). Results showed a significant 53 % (39/74) remission rate in depression symptoms after the acute phase. In adjusted models, baseline language domain score was associated with a higher odd of remission (Odds Ratio, 1.09, 95 % CI = 1.03-1.17, p = 0.004) and greater improvement in MADRS at the end of the acute phase (β =-0.97; 95 % CI, -1.74 to -0.20; P = 0.02). The likelihood of remission was not significantly associated with baseline immediate or delayed memory, visuospatial/constructional, or attention scores. In the continuation phase, improvements in immediate and delayed memory and attention persisted, with additional gains in visuospatial and language domains. Limitations included an open-label design, potential practice effects, and ongoing psychotropic medication use. Overall, the study suggests cognitive improvement, not deterioration, associated with serial IV ketamine administrations for TRD. These findings encourage future studies with larger sample sizes and longer follow-up periods to examine any potential for deleterious effect with recurrent ketamine use for TRD. Trial Registration: ClinicalTrials.gov: NCT03156504.

Effect of intraoperative and/or postoperative esketamine administration on preventing postpartum depression: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the impact of intraoperative and/or postoperative esketamine application on the prevention of postpartum depression (PPD). PubMed, Embase, and Web of Science were thoroughly searched for eligible randomized controlled trials (RCTs) regarding the application of esketamine for postnatal depression prevention. Nine RCTs including 1277 participants were involved in the final analysis. It was found that intraoperative and/or postoperative administration of esketamine significantly reduced the PPD incidence and the Edinburgh Postnatal Depression Scores in the early postoperative period. Meanwhile, esketamine lowered the occurrence of postoperative nausea and vomiting with no influence on other psychiatric symptoms.

A retrospective analysis of iv ketamine outcome on hospitalisations in an unselected psychiatric sample

OBJECTIVE

This study aims to explore the outcome with iv ketamine treatment in a real-world clinical setting, primarily measured as posttreatment days hospitalised.

METHODS

The psychiatric medical records of 46 patients having received iv ketamine on a psychiatric treatment indication between 2015 and 2018 were retrospectively examined. Analysis comparing the number and duration of hospital admissions before and after ketamine treatment as well as logistic regression analysis to investigate clinical predictors of effectiveness, were performed. To assess patients' severity of depressed symptoms records were screened for MADRS-S scores.

RESULTS

No significant difference between pre- and posttreatment hospital days (p = 0.170), or number of hospitalisations (p = 0.740) were found. The response rate was 31% and remission rate 21%. None of the predictors showed statistical significance in the logistic model.

CONCLUSION

Iv ketamine treatment showed effectiveness in reducing depressive symptoms even with complex patients in a real-world clinical setting. However, this did not translate to a reduction in hospitalisation. Highlighting the multifaceted challenges posed when implementing iv ketamine treatment in clinical practice.

Ketamine and its enantiomers for depression: a bibliometric analysis from 2000 to 2023

Ketamine has demonstrated rapid and sustained antidepressant effects, marking its emergence as an innovative treatment of depression. Despite the growing number of preclinical and clinical studies exploring the antidepressant effects of ketamine and its enantiomers, a comprehensive bibliometric analysis in this field has yet to be conducted. This study employs bibliometric methods and visualization tools to examine the literature and identify key topics related to the antidepressant effects of ketamine and its enantiomers. We sourced publications on the antidepressant effects of ketamine and its enantiomers from the Web of Science Core Collection (WOSCC) database, covering the period from 2000 to 2023. Tools such as VOSviewer, CiteSpace and the R package "bibliometrix" were utilized for visual analysis. The study included 4,274 publications, with a notable increase in publications peaking in 2022. Co-occurrence analysis highlighted two primary research focal points: the efficacy and safety of ketamine and its enantiomers in treating depression, and the mechanisms behind their antidepressant effects. In conclusion, this analysis revealed a significant increase in research on the antidepressant effects of ketamine and its enantiomers over the past two decades, leading to the approval of esketamine nasal spray for treatment-resistant depression. The rapid antidepressant effects of ketamine have spurred further studies into its mechanisms of action and the search for new antidepressants with fewer side effects.

Ketamine Induced Acute Systolic Heart Failure

Background

Studies have shown major cardiovascular effects associated with ketamine use disorder including dose-dependent negative inotropic effects. Preoperative ketamine use has been linked to ketamine-induced stress cardiomyopathy.

Case presentation

A 28-year-old female with a history of recurrent cystitis and ketamine use disorder (twice weekly for 14 years) presented with bilateral lower extremity oedema and shortness of breath for 3 months. She was tachycardic with a troponin level of 0.07 ng/ml and a B-type natriuretic peptide (BNP) level of 2511 pg/ml. Electrocardiogram showed normal sinus rhythm and transthoracic echocardiography (TTE) showed left ventricular ejection fraction (EF) of 15%, dilated left ventricle, and severe tricuspid and mitral regurgitation. Computed tomography (CT) scan of the chest and abdomen showed bilateral pleural effusions with congestive hepatopathy and ascites. The patient was started on intravenous furosemide, metoprolol, and sacubitril/valsartan. Rheumatological workup including complement levels, and antinuclear anti-double-stranded DNA was negative. A repeat TTE 2 weeks later revealed an EF of 25% and moderate tricuspid regurgitation. Four months later, the EF was 54% with normal left ventricular cavity size.

Conclusion

Although ketamine use disorder is increasing, data on long-term side effects is minimal. Screening for ketamine use disorders should be considered in patients presenting with acute systolic heart failure. Long-term studies are needed to evaluate the benefits of adding ketamine screening to standard urine toxicology.

LEARNING POINTS

Ketamine use disorder can lead to severe cardiovascular complications, including acute systolic heart failure, likely due to its direct negative inotropic effects and dose-dependent impact on cardiac function.Clinicians should consider screening for ketamine use disorder in young adults presenting with acute systolic heart failure, especially when other common aetiologies have been ruled out.Early recognition and prompt treatment of ketamine-induced heart failure with diuretics and guideline-directed medical therapy can lead to significant improvement in cardiac function, but long-term management should also focus on ensuring cessation of ketamine use disorder.

Subcutaneous ketamine reduces suicide risk and improves functioning in depression: A proof-of-concept study

This investigation explores the efficacy of subcutaneous ketamine for mitigating depressive symptoms and suicidal ideation, addressing a crucial need for rapid-onset treatments in severe depression cases. It introduces an innovative approach to administering an NMDA receptor antagonist, significantly advancing psychopharmacological methods for treating suicidal behaviors as distinct entities, even within depressive episodes. The study's objective is to assess the impact of subcutaneous ketamine on diminishing suicidal thoughts and mood symptoms during depressive episodes through a naturalistic, prospective observational design. Conducted at Hospital de Clínicas de Porto Alegre, Brazil, between 2021 and 2023, the study involved 26 patients undergoing a current depressive episode. Of these, 23 completed the acute phase of treatment, and 18 were followed up for 6 months. The treatment regimen commenced with a ketamine dose of 0.5 mg/kg, which was adjusted according to individual responses under psychiatric supervision. The findings revealed substantial decreases in Columbia Suicide Severity Rating Scale scores following multiple ketamine sessions, with most patients achieving remission after approximately eight sessions. A notable reduction in depressive symptoms was also observed. A clear dose-response relationship was established, indicating that higher doses of ketamine were associated with more significant improvements in depressive symptoms, suicidal ideation, and overall functionality. Follow-up assessments suggested that these improvements were sustained over time. The subcutaneous administration of ketamine was generally well-tolerated, with minor and short-lived side effects. The study posits that subcutaneous ketamine may present a promising solution for treating severe depression accompanied by suicidal tendencies, particularly considering its positive influence on patient functionality and well-being. This method could offer a cost-effective and accessible treatment alternative, especially relevant in settings with limited resources. Given its potential in reducing long-term disability and economic viability, the study advocates for its broader application and further validation through larger, controlled trials. Trial Registration: ClinicalTrials.gov NCT05249309.

Effects of the PAM of mGluR2, JNJ-46356479, on brain apoptotic protein levels in a mouse model of schizophrenia

Current treatment for schizophrenia (SZ) ameliorates the positive symptoms, but is inefficient in treating the negative and cognitive symptoms. The SZ glutamatergic dysfunction hypothesis has opened new avenues in the development of novel drugs targeting the glutamate storm, an inducer of progressive neuropathological changes. Positive allosteric modulators of metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), reduce the presynaptic release of glutamate, which has previously been demonstrated to attenuate glutamate- and dopamine-induced apoptosis in human neuroblastoma cell cultures. We hypothesised that JNJ treatment would modify the brain levels of apoptotic proteins in a mouse model of ketamine (KET)-induced schizophrenia. We analysed the levels of proapoptotic (caspase-3 and Bax) and antiapoptotic (Bcl-2) proteins by western blot in the prefrontal cortex and hippocampus of JNJ-treated mice. JNJ attenuated apoptosis in the brain by partially restoring the levels of the antiapoptotic Bcl-2 protein, which is significantly reduced in animals exposed to KET. Additionally, a significant inverse correlation was observed between proapoptotic protein levels and behavioural deficits in the mice. Our findings suggest that JNJ may attenuate brain apoptosis in vivo, as previously described in cell cultures, providing a link between neuropathological deficits and SZ symptomatology.

Perspectives in treatment-resistant depression: esketamine and electroconvulsive therapy

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

Depression, an unmet health need in Africa: Understanding the promise of ketamine

In Africa, there is currently a paucity of data on the epidemiology of depression, its treatment and management. The prevalence of depression is severely underestimated, with unique circumstances and societal risk factors associated with depression and its public awareness. Treating and managing depression is confounded by an inaccessibility to efficient and low-cost treatments for patients with depression. The aetiology of depression is multifactorial, with various theories implicating multiple neuronal networks. Despite this, the treatment of depression is one-dimensional focussing on outdated theories of depression and mainly targeting dysfunctional neurotransmitter pathways. Hence, it is not surprising that there is a significant increase in the prevalence of patients suffering from treatment resistant depression (TRD), with a large portion of patients deriving little clinical benefit from these traditional anti-depressant therapies. This highlights the need for more effective treatment strategies for depression, especially applicable to resource limited environments such as Africa, where there is little investment in public healthcare resources towards managing mental health disorders. The clinical potential of using ketamine in managing depression has received considerable attention in the past two decades, with the FDA approving esketamine for the management of TRD in 2019. This widespread attention has significantly increased ketamine's appeal as a novel antidepressant. Consequently, many ketamine infusion clinics have been established in Africa. However, there is little regulation or guidance for ketamine infusions. Furthermore, while esketamine is expensive and hence inaccessible to a large portion of the African population, racemic ketamine is significantly cheaper and has demonstrated clinical potential. However, there is currently a limited understanding of the neurological mechanisms of action of racemic ketamine in treating and managing depression, especially in a diverse African population. Therefore, this review aims to provide an African context of depression and the therapeutic potential of ketamine by highlighting aspects of its molecular mechanism of action.

Ketamine for major depressive disorder during an inpatient psychiatric admission: Effectiveness, adverse events, and lessons learned

OBJECTIVE

Most studies examining the efficacy of ketamine for Major Depressive Disorder (MDD) have been conducted in outpatient or mixed inpatient/outpatient settings. Less is known about effectiveness and tolerability of ketamine for psychiatrically hospitalized patients. Efficacy and tolerability data from a naturalistic sample of acute inpatients may help inform institutions considering ketamine therapy for inpatient services.

METHODS

We performed a retrospective chart review of inpatients with non-psychotic MDD treated during the initial 3 years of a ketamine infusion program. Treatment effectiveness was defined using change in Montgomery Asberg Depression Rating Scale (MADRS) scores over five infusions. MDD treatment response was defined by a 50 % reduction of MADRS score, and remission was defined as MADRS score ≤ 10 at any point during the treatment. We also report the frequency of adverse events.

RESULTS

41 patients with MDD were treated and had outcome data. 19 patients (46.5 %) met criteria for response and 15 patients (26.5 %) met criteria for remission during treatment. Four patients (10 %) had adverse psychological or behavioral outcomes.

LIMITATIONS

MADRS scales were administered by psychiatrists, psychologists, and trainees in each discipline who did not undergo standardized training in scale administration. Consistent data regarding the race/ethnicity of the patients was not available.

CONCLUSION

Twice weekly racemic ketamine infusion is an effective treatment option for patients hospitalized with MDD. Unmonitored or at home ketamine therapy may pose substantial risks.

Effects of ketamine and esketamine on preventing postpartum depression after cesarean delivery: A meta-analysis

BACKGROUND

Ketamine and esketamine has been suggested to have potential efficacy in preventing postpartum depression (PPD) recent years. The aim of this meta-analysis was to evaluate the effectiveness of ketamine and esketamine on PPD after cesarean delivery.

METHODS

We systematically searched PubMed, Embase, and the Cochrane Library for studies investigating the efficacy of ketamine and esketamine in preventing PPD. The primary outcomes of this study were risk ratios (RRs) and EPDS scores (Edinburgh Postnatal Depression Scale) in relation to PPD after ketamine and esketamine. The second outcomes were the postoperative adverse events.

RESULTS

Thirteen randomized controlled trials (RCTs) and one retrospective study including 2916 patients were analyzed, including six on the use of ketamine and eight on the use of esketamine. The risk ratios and EPDS scores of PPD were significantly decreased in the ketamine/esketamine group compared to those in the control group in one week and four weeks postoperative periods. Subgroup analyses showed that high dosage, administrated in patient controlled intravenous analgesia (PCIA) method and only esketamine exhibited a significant reduction in the incidence and EPDS scores of PPD in one week and four week postoperative. However, the incidences of postoperative adverse events, such as dizziness, diplopia, hallucination, and headache were significantly higher in the ketamine/esketamine group than that in the control group.

CONCLUSION

Ketamine and esketamine appear to be effective in preventing PPD in the one week and four week postoperative periods after cesarean delivery with moderate certainty of evidence. But they can also lead to some short-term complications too. Future high-quality studies are needed to confirm the efficacy of ketamine and esketamine in different countries.

Effects of ketamine, propofol and isoflurane on electrocardiographic variables in clinically healthy dogs premedicated with medetomidine and midazolam

The purpose of this study was to investigate the effects of three anesthetic agents, with premedication of medetomidine and midazolam, on electrocardiographic variables in dogs. Ten adult mixed breed dogs were used in a crossover design study, where they received ketamine, propofol and isoflurane treatments with a one-week washout period between them. In all three groups, medetomidine was administered first followed by midazolam after 15 min. Then, after 20 min, group 1 received ketamine intravenously (IV), group 2 received propofol (IV), and group 3 received isoflurane (inhalation). In all dogs, electrocardiographs were taken before and after premedication's, as well as every 15 min during anesthesia. Medetomidine significantly decreased heart rate and P wave amplitude and increased PR interval, R wave amplitude, QT interval, and T wave amplitude. Midazolam increased the amplitude of the R and T waves. Ketamine increased the heart rate and PR interval. Propofol increased the heart rate for up to 15 min, decreased the PR interval for up to 30 min, and the QT interval for up to 45 min. Isoflurane increased the heart rate and decreased the amplitude of R and T waves. The results showed that the drugs used in this study did not have many side effects on electrocardiographic variables and could be used without serious concern. The most important side effects observed were a severe reduction in heart rate and 1st degree atrioventricular (AV) block and, to a lesser extent, 2nd degree AV block caused by medetomidine and midazolam which were masked by the anesthetics.