Study on the Mass Spectrometry Fragmentation Patterns for Rapid Screening and Structure Identification of Ketamine Analogues in Illicit Powders.

Ketamine analogues have been emerging in recent years and are causing severe health and social problems worldwide. Ketamine analogues use 2-phenyl-2-aminocyclohexanone as the basic structure and achieve physiological reactions similar to or even more robust than the prototype of ketamine by changing the substituents on the benzene ring (R1 and R2) and amine group (RN1). Therefore, the mass spectrometry (MS) fragmentation pathways and fragments of ketamine analogues have certain regularity. Eight ketamine analogues are systematically investigated by GC-QTOF/MS and LC-Q-Orbitrap MS/MS with the positive mode of electrospray ionization. The MS fragmentation patterns of ketamine analogues are summarized according to high-resolution MS data. The α-cleavage of carbon bond C1-C2 in the cyclohexanone moiety and further losses of CO, methyl radical, ethyl radical and propyl radical are the characteristic fragmentation pathways of ketamine analogues in EI-MS mode. The loss of H2O or the sequential loss of RN1NH2, CO and C4H6 are the distinctive fragmentation pathways of ketamine analogues in ESI-MS/MS mode. Moreover, these MS fragmentation patterns are first introduced for the rapid screening of ketamine analogues in suspicious powder. Furthermore, the structure of the ketamine analogue in suspicious powder is 2-(Methylamino)-2-(o-tolyl)cyclohexan-1-one, which is further confirmed by NMR. This study contributes to the identification of the chemical structure of ketamine analogues, which can be used for the rapid screening of ketamine analogues in seized chemicals.

Simultaneous quantitation of ketamine, norketamine and dehydronorketamine in human milk using a novel ultra high-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) assay.

There is a paucity of data on the transfer of ketamine from maternal blood into human milk. Quantification of ketamine in human milk provides information about the potential exposure of the infant to ketamine and its metabolites from the mother during lactation. A highly specific, reproducible, and sensitive UPLC-MS/MS based analytical method was developed and validated for the quantitation of ketamine and its metabolites (norketamine and dehydronorketamine) in human milk. Samples were subjected to a simple protein precipitation and ketamine-d4 and norketamine-d4 were used as internal standards. Separation of the analytes was achieved using an Acquity UPLC equipped with BEH RP18 1.7 µm, 2.1 × 100 mm column. Mass spectrometric analysis of the analyte ions was carried out using electrospray with positive ionization and multiple reaction monitoring mode. The assay was linear over a concentration range of 1-100 ng/mL for ketamine and norketamine, and 0.1-10 ng/mL for dehydronorketamine. Acceptable intra-day and inter-day accuracy and precision were observed for all the analytes. High recovery of the analytes and minimal matrix effect were observed. Stability of analytes was confirmed at the tested conditions. This assay was successfully used to measure analytes in human milk samples collected from lactating women enrolled in a clinical research study. This is the first validated method that simultaneously quantified ketamine and its metabolites in human milk.

Perfil de muestras de ketamina analizadas entre el 2017-2022 / Profile of ketamine´s samples analyzed during 2017-2022

La ketamina es un anestésico disociativo que actúa como antagonista no competitivo del receptor NMDA (N-metil-D-aspartato). Actualmente se utiliza como anestésico y analgésico en medicina veterinaria y en algunas áreas de la medicina humana. La sensación disociativa que produce la ketamina comúnmente denominada “K-Hole o fuera del cuerpo”, es placentera para algunos individuos, y ha llevado a la ketamina a ganar popularidad como droga recreativa. En el presente estudio se evaluó la cantidad de muestras positivas a ketamina provenientes de distintas fiscalías de Chile entre el 2017-2022, colocando atención a muestras liquidas transparentes, donde se cuantificaron 49 muestras mediante HPLC/UV-DAD, obteniendo resultados en porcentaje de ketamina clorhidrato. Se observó si existe una relación en cuanto a la concentración y procedencia de incautación con productos veterinarios o humanos de venta legal que contienen esta sustancia. Se puede concluir que entre los años 2017 al 2022 hubo un aumento significativo en el análisis de muestras positivas a ketamina pasando de 72 muestras en el 2017 a 3202 muestras el 2022. En cuanto a las muestras liquidas transparentes positivas a ketamina, no presentaron una tendencia definida en los años evaluados. Con respecto a la concentración de ketamina clorhidrato, se aprecia que las concentraciones se encuentran en el rango de 8-12%, observándose una directa relación con la ketamina de uso veterinario que se encuentra al 10% de ketamina clorhidrato, paralelamente, la procedencia de incautación de ketamina liquida a nivel nacional, se concentra en las regiones de Arica y Parinacota y Tarapacá.(AU)

Ketamine is a dissociative anesthetic that act as non-competitive antagonist at N-methyl-D-aspartate (NMDA) receptors. Nowadays, ketamine is used in veterinary medicine and some areas on human medicine as anesthetic and analgesic. The dissociative effect produced by ketamine called “k-Hole or out of body” is pleasant to some individuals, and has led to it gaining in popularity as a recreational drug. The present study evaluated the number of positives samples for ketamine from different Chilean prosecutors between 2017 and 2022. In addition, the study paid attention in transparent liquid samples, quantifying 49 of them at random by HPLC/UV-DAD obtain the percentage of ketamine hydrochloride, and correlate this result with the concentration of veterinary and human drugs for legal sale, also, evaluate the origin of seizure of these liquid samples at the national level. Between 2017 and 2022, there was a significant increase of positive samples for ketamine, from 72 samples in 2017 to 3202 samples in 2022. Otherwise, transparent liquid samples positives for ketamine did not show a defined trend in the years evaluated. Results of the quantification of liquid samples are in the range of 8-12%; these results show a direct relation with veterinary ketamine products, which are available at 10% of ketamine hydrochloride. Additionally, the origin of seizure of liquid ketamine at the national level is concentrated in the north regions of Chile: Arica and Parinacota, and Tarapacá.(AU)

Association of S(+) ketamine, dexmedetomidine and butorphanol for chemical restraint in scarlet macaws (Ara macao) / Associação cetamina S(+), dexmedetomidina e butorfanol na contenção química de araracangas (Ara macao)

The present study aimed at assessing the effects of combining 20 mg/kg S(+) ketamine with 25 µg/kg dexmedetomidine and 0.4 mg/kg butorphanol on the physiological parameters and anesthetic recovery time and score of eight captive scarlet macaw (Ara macao) specimens. These specimens were captured at the Marabá Zoobotanic Foundation (Fundação Zoobotânica de Marabá), Pará, using butterfly and mist nets, and subsequently subjected to the proposed protocol. The following physiological parameters were evaluated: heart rate (HR), respiratory rate (RR), saturation of peripheral oxygen (SpO2), body temperature (BT), and non-invasive blood pressure 5 min after drug administration (M0) and every 10 min thereafter (M1‒M5), with a total of 55 min of analysis of anesthetic effects. Glycemia was measured 5 min after drug administration and every 30 min thereafter. Anesthetic induction and recovery times were also determined. Among the parameters evaluated in this study, both HR and BT significantly decreased throughout the anesthetic period, with the lowest levels at 55 min after drug administration (M5). In contrast, RR did not significantly differ, and all animals remained stable, maintaining an RR close to a mean of 20 ± 8 cpm. Throughout the anesthetic period, SpO2was 92 ± 5%, with no significant difference. The birds remained under spontaneous ventilation and without oxygen supplementation. Systolic, diastolic, and mean blood pressures remained stable, with no significant differences in any of these measurements. At M0 and M3, the glycemia decreased slightly, albeit with no significant difference justifying an adverse effect or even hypoglycemia. The anesthetic induction time, from M0 to decubitus, was 2.4 ± 0.7 min. The anesthetic recovery time, from M0 to effortless bipedal position and adequate phalangeal flexion, was 99.3 ± 32.4 min. The sedation was assessed as intense, and the anesthetic recovery was rated excellent in 62.5% and good in 37.5% of the animals.(AU)

O presente estudo objetivou avaliar os efeitos do uso da cetamina S(+) 20 mg/kg associada à dexmedetomidina 25 µg/kg e butorfanol 0,4 mg/kg sobre os parâmetros fisiológicos, tempo e qualidade da recuperação anestésica de araracangas (Ara macao). Foram utilizados oito espécimes de Ara macao cativas da Fundação Zoobotânica de Marabá, Pará. A captura foi realizada com o uso de puçá e rede de contenção e em seguida as aves foram submetidas ao protocolo proposto. Foram avaliados: frequência cardíaca, frequência respiratória, saturação parcial da oxihemoglobina (SpO2), temperatura corporal e pressão arterial não-invasiva a partir de 5 minutos após a aplicação dos fármacos (M0) e a cada 10 minutos seguintes (M1, M2, M3, M4 e M5), totalizando 55 minutos de contemplação dos efeitos anestésicos. A glicemia foi avaliada aos 5 minutos da aplicação dos fármacos e repetida após 30 minutos. Também foi determinado o tempo de indução e de recuperação. Dentre os parâmetros avaliados, a frequência cardíaca e a temperatura demonstraram queda estatisticamente significativa ao longo do período anestésico, ambas com os menores valores registrados aos 55 minutos após a aplicação dos fármacos (M5). A frequência respiratória não apresentou diferença estatística e todos os animais se mantiveram estáveis e com a frequência próxima a média de 20±8mpm. A saturação da oxihemoblobina (SpO2) ao longo do período anestésico foi de 92±5%, não houve diferença estatisticamente relevante, as aves permaneceram sob ventilação espontânea e sem suplementação de oxigênio. As pressões arteriais sistólica, diastólica e média, mantiveram-se estáveis e não houve diferença estatística para nenhuma dessas medidas. A glicemia, mensurada em M0 e M3 demonstrou queda discreta, sem diferença significativa capaz de justificar um efeito adverso ou mesmo hipoglicemia. O tempo de indução, desde aplicação dos anestésicos até o decúbito, foi de 2,4±0,7 minutos. O tempo de recuperação, compreendido desde a aplicação dos fármacos (M0) até a constatação da posição bipedal sem esforço e adequada flexão das falanges, foi de 99,3±32,4 minutos. A qualidade de sedação foi considerada intensa e a recuperação anestésica foi classificada como ótima para 62,5% e boa para 37,5% dos animais.(AU)

Ketamine and Norketamine: Enantioresolution and Enantioselective Aquatic Ecotoxicity Studies.

Ketamine is a chiral drug used for various clinical purposes but often misused. It is metabolized to norketamine, an active chiral metabolite. Both substances have been detected in environmental matrices, but studies about their enantioselective toxic effects are scarce. In the present study, the enantiomers of ketamine and norketamine were separated by a semipreparative enantioselective liquid chromatography method, and their toxicity was investigated in different aquatic organisms. The enantioseparation was achieved using a homemade semipreparative chiral column. Optimized conditions allowed the recovery of compounds with enantiomeric purity higher than 99%, except for (R)-ketamine (97%). The absolute configuration of the enantiomers was achieved by experimental electronic circular dichroism (ECD). The ecotoxicity assays were performed with the microcrustacean Daphnia magna and the protozoan Tetrahymena thermophila using Toxkit MicroBioTests. Different concentrations were tested (0.1-10 000 µg/L) to include environmental levels (~0.5-~100 µg/L), for racemates (R,S) and the isolated enantiomers (R or S) of ketamine and norketamine. No toxicity was observed in either organism at environmental levels. However, at greater concentrations, (R,S)-ketamine presented higher mortality for D. magna compared with its metabolite (R,S)-norketamine (85 and 20%, respectively), and the (S)-ketamine enantiomer showed higher toxicity than the (R)-ketamine enantiomer. In addition, (S)-ketamine also presented higher growth inhibition than (R)-ketamine for T. thermophila at the highest concentrations (5000 and 10 000 µg/L). Contrary to D. magna, growth inhibition was observed for both enantiomers of norketamine and in the same magnitude order of the (S)-ketamine enantiomer. The results showed that the 2 organisms had different susceptibilities to norketamine and that the toxicity of ketamine at high concentrations is enantioselective for both organisms. Environ Toxicol Chem 2022;41:569-579. © 2020 SETAC.

Molecular mechanisms underlying the antidepressant actions of arketamine: beyond the NMDA receptor.

The discovery of robust antidepressant actions exerted by the N-methyl-D-aspartate receptor (NMDAR) antagonist (R,S)-ketamine has been a crucial breakthrough in mood disorder research. (R,S)-ketamine is a racemic mixture of equal amounts of (R)-ketamine (arketamine) and (S)-ketamine (esketamine). In 2019, an esketamine nasal spray from Johnson & Johnson was approved in the United States of America and Europe for treatment-resistant depression. However, an increasing number of preclinical studies show that arketamine has greater potency and longer-lasting antidepressant-like effects than esketamine in rodents, despite the lower binding affinity of arketamine for the NMDAR. In clinical trials, non-ketamine NMDAR-related compounds did not exhibit ketamine-like robust antidepressant actions in patients with depression, despite these compounds showing antidepressant-like effects in rodents. Thus, the rodent data do not necessarily translate to humans due to the complexity of human psychiatric disorders. Collectively, the available studies indicate that it is unlikely that NMDAR plays a major role in the antidepressant action of (R,S)-ketamine and its enantiomers, although the precise molecular mechanisms underlying antidepressant actions of (R,S)-ketamine and its enantiomers remain unclear. In this paper, we review recent findings on the molecular mechanisms underlying the antidepressant actions of (R,S)-ketamine and its potent enantiomer arketamine. Furthermore, we discuss the possible role of the brain-gut-microbiota axis and brain-spleen axis in stress-related psychiatric disorders and in the antidepressant-like action of arketamine. Finally, we discuss the potential of arketamine as a treatment for cognitive impairment in psychiatric disorders, Parkinson's disease, osteoporosis, inflammatory bowel diseases, and stroke.

Structural basis of ketamine action on human NMDA receptors.

Ketamine is a non-competitive channel blocker of N-methyl-D-aspartate (NMDA) receptors1. A single sub-anaesthetic dose of ketamine produces rapid (within hours) and long-lasting antidepressant effects in patients who are resistant to other antidepressants2,3. Ketamine is a racemic mixture of S- and R-ketamine enantiomers, with S-ketamine isomer being the more active antidepressant4. Here we describe the cryo-electron microscope structures of human GluN1-GluN2A and GluN1-GluN2B NMDA receptors in complex with S-ketamine, glycine and glutamate. Both electron density maps uncovered the binding pocket for S-ketamine in the central vestibule between the channel gate and selectivity filter. Molecular dynamics simulation showed that S-ketamine moves between two distinct locations within the binding pocket. Two amino acids-leucine 642 on GluN2A (homologous to leucine 643 on GluN2B) and asparagine 616 on GluN1-were identified as key residues that form hydrophobic and hydrogen-bond interactions with ketamine, and mutations at these residues reduced the potency of ketamine in blocking NMDA receptor channel activity. These findings show structurally how ketamine binds to and acts on human NMDA receptors, and pave the way for the future development of ketamine-based antidepressants.

Stereoselective ketamine effect on cardiac output: a population pharmacokinetic/pharmacodynamic modelling study in healthy volunteers.

BACKGROUND: Ketamine has cardiac excitatory side-effects. Currently, data on the effects of ketamine and metabolite concentrations on cardiac output are scarce. We therefore developed a pharmacodynamic model derived from data from a randomised clinical trial. The current study is part of a larger clinical study evaluating the potential mitigating effect of sodium nitroprusside on the psychedelic effects of ketamine. METHODS: Twenty healthy male subjects received escalating esketamine and racemic ketamine doses in combination with either placebo or sodium nitroprusside on four visits: (i) esketamine and placebo, (ii) esketamine and sodium nitroprusside, (iii) racemic ketamine and placebo, and (iv) racemic ketamine and sodium nitroprusside. During each visit, arterial blood samples were obtained and cardiac output was measured. Nonlinear mixed-effect modelling was used to analyse the cardiac output time-series data. Ketamine metabolites were added to the model in a sequential manner to evaluate the effects of metabolites. RESULTS: A model including an S-ketamine and S-norketamine effect best described the data. Ketamine increased cardiac output, whereas modelling revealed that S-norketamine decreased cardiac output. No significant effects were detected for R-ketamine, metabolites other than S-norketamine, or sodium nitroprusside on cardiac output. CONCLUSIONS: S-Ketamine, but not R-ketamine, increased cardiac output in a dose-dependent manner. In contrast to S-ketamine, its metabolite S-norketamine reduced cardiac excitation in a dose-dependent manner. CLINICAL TRIAL REGISTRATION: Dutch Cochrane Center 5359.

Dextran sulfate sodium-induced inflammation and colitis in mice are ameliorated by (R)-ketamine, but not (S)-ketamine: A role of TrkB signaling.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that causes long-lasting inflammation and colitis in the gastrointestinal tract. Depression is a common symptom in patients with UC. (R)-ketamine is a new safer antidepressant than (R,S)-ketamine and (S)-ketamine. Here, we examined the effects of two ketamine enantiomers on the dextran sulfate sodium (DSS)-induced colitis model of UC. Ingestion of 3% DSS in drinking water for 14 days increased the scores of Disease Activity Index (DAI) in mice. Repeated administration of (R)-ketamine (10 mg/kg/day, 14 days or last 7 days), but not (S)-ketamine (10 mg/kg/day, 14 days or last 7 days), significantly ameliorated the increased DAI score and increased blood levels of interleukin-6 (IL-6) in DSS-treated mice. In addition, (R)-ketamine, but not (S)-ketamine, attenuated the reduced colonic length in DSS-treated mice. Furthermore, DSS-induced increased DAI score and blood IL-6 levels were significantly ameliorated after subsequent repeated administration of (R)-ketamine (10 mg/kg/day for last 7 days), but not 5-aminosalicyclic acid (50 mg/kg/day for last 7 days). Moreover, the pretreatment with a tropomyosin-receptor-kinase B (TrkB) antagonist ANA-12 (0.5 mg/kg) significantly blocked the beneficial effects of (R)-ketamine in DSS-induced UC model. The study shows that (R)-ketamine can produce beneficial effects in DSS-induced colitis model through TrkB stimulation. Therefore, (R)-ketamine may be a novel therapeutic drug for inflammatory bowel diseases such as UC.

Antidepressant Actions of Ketamine: Potential Role of L-Type Calcium Channels.

Recently, the United States Food and Drug Administration approved esketamine, the S-enantiomer of ketamine, as a fast-acting therapeutic drug for treatment-resistant depression. Although ketamine is known as an N-methyl-d-aspartate (NMDA) receptor antagonist, the underlying mechanisms of how it elicits an antidepressant effect, specifically at subanesthetic doses, are not clear and remain an advancing field of research interest. On the other hand, high-dose (more than the anesthetic dose) ketamine-induced neurotoxicity in animal models has been reported. There has been progress in understanding the potential pathways involved in ketamine-induced antidepressant effects, some of which include NMDA-receptor antagonism, modulation of voltage-gated calcium channels, and brain-derived neurotrophic factor (BDNF) signaling. Often these pathways have been shown to be linked. Voltage-gated L-type calcium channels have been shown to mediate the rapid-acting antidepressant effects of ketamine, especially involving induction of BDNF synthesis downstream, while BDNF deficiency decreases the expression of L-type calcium channels. This review focuses on the reported studies linking ketamine's rapid-acting antidepressant actions to L-type calcium channels with an objective to present a perspective on the importance of the modulation of intracellular calcium in mediating the effects of subanesthetic (antidepressant) versus high-dose ketamine (anesthetic and potential neurotoxicant), the latter having the ability to reduce intracellular calcium by blocking the calcium-permeable NMDA receptors, which is implicated in potential neurotoxicity.

Rapid tolerance to behavioral effects of ethanol in rats: Prevention by R-(-)-ketamine.

R-(-)-ketamine has emerged as a potentially improved medication over that of the (S)-isomer (marketed as Spravato for depression). Recent data have suggested (R)-ketamine could have value in the treatment of substance use disorder. The present set of experiments was undertaken to examine whether (R)-ketamine might prevent tolerance development. Rapid ethanol (ETOH) tolerance was studied since racemic ketamine had previously been shown to block this tolerance development in rats. In the present study, male Sprague-Dawley rats were given two large doses of ETOH on Day 1 (2.3 + 1.7 g/kg) and 2.3 g/kg ETOH on Day 2. Animals were tested for effects of 2.3 g/kg ETOH on grip strength, inclined screen performance and rotarod performance on Day 1 with or without (R)-ketamine as a pretreatment. (R)-ketamine alone was tested at the highest dose studied (10 mg/kg) and did not significantly influence any dependent measure. (R)-ketamine (1-10 mg/kg) did not alter the acute effects of ETOH except for enhancing the effects of ETOH on the inclined screen test at 3 mg/kg. Between-subjects analysis documented that tolerance developed to the effects of ETOH only on the measure of grip strength. (R)-ketamine (3 mg/kg) given prior to ETOH on Day 1 exhibited a strong trend toward preventing tolerance development (p = 0.062). The present results extend prior findings on the potential value of (R)-ketamine in substance abuse disorder therapeutics and add to the literature on NMDA receptor blockade as a tolerance-regulating mechanism.

Crocins, the Bioactive Components of Crocus sativus L., Counteract the Disrupting Effects of Anesthetic Ketamine on Memory in Rats.

Consistent experimental evidence suggests that anesthetic doses of the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine cause severe memory impairments in rodents. Crocins are among the various bioactive ingredients of the plant Crocus sativus L., and their implication in memory is well-documented. It has not yet been elucidated if crocins are able to attenuate the memory deficits produced by anesthetic ketamine. The present study was undertaken aiming to clarify this issue in the rat. For this aim, the object recognition, the object location and the habituation tests, reflecting non-spatial recognition memory, spatial recognition memory and associative memory, respectively, were utilized. A post-training challenge with crocins (15-30 mg/kg, intraperitoneally (i.p.), acutely) counteracted anesthetic ketamine (100 mg/kg, i.p.)-induced performance impairments in all the above-mentioned behavioral memory paradigms. The current findings suggest that crocins modulate anesthetic ketamine's amnestic effects.

Molecular evolution of a cytochrome P450 for the synthesis of potential antidepressant (2R,6R)-hydroxynorketamine.

Saturation mutagenesis at seven first-sphere residues of the cytochrome P450 monooxygenase 154E1 (CYP154E1) from Thermobifida fusca YX was applied to construct a variant with only three substitutions that enabled the effective two-step synthesis of the potential antidepressant (2R,6R)-hydroxynorketamine. A recombinant E. coli whole-cell system was essential for GC/MS based medium-throughput screening and at the same time facilitated the oxidation of the substrate (R)-ketamine at a higher scale for product isolation and subsequent NMR analysis.

Therapeutic Mechanisms of Ketamine.

Major depressive disorder is the greatest burden of developed countries in the context of morbidity caused by mental disorders. Until recent, ketamine has been mostly used for anesthesia, analgesia, sedation and treatment of chronic pain syndromes. However, unique pharmacodynamic properties of ketamine have increased interests in it's use for treatment of depression. It is assumed that ketamine reverses synaptic chronic stress pathology within one day of administration by postsynaptic glutamate activation, providing synaptic connectivity restoration that last for days or weeks. Potential glutamatergic agents, in context of treatment of major depressive disorder are not entirely novel phenomenon. Considering the aforementioned, current neurobiological view of depression as a solely monoaminergic phenomenon should be reassessed in order to prompt discovery of putative antidepressant drugs of novel generation. Acute side effects, such as increased salivation, increase in heart rate, systemic arterial pressure and intracranial pressure necessitate careful monitoring during intravenous administration of ketamine, even in subanesthetic doses. However, major burden of ketamine administration lies in it's ability to produce psychotomimetic side effects and emergence delirium. Esketamine nasal spray has now been widely approved and is considered safe in terms of acute side effects, tolerability and consistent therapeutic benefit.

Repurposing of Drugs-The Ketamine Story.

An intranasal formulation of esketamine, the S enantiomer of ketamine, in conjunction with an oral antidepressant, has been approved by the FDA for treating treatment-resistant major depressive disorder (TRD) in 2019, almost 50 years after it was approved as an intravenous anesthetic. In contrast to traditional antidepressants, ketamine shows a rapid (within 2 h) and sustained (∼7 days) antidepressant effect and has significant positive effects on antisuicidal ideation. Ketamine's antidepressant mechanism is predominantly mediated by the N-methyl-d-aspartate receptor (NMDA) receptor, although NMDA-independent mechanisms are not ruled out. At the neurocircuitry level, ketamine affects the brain's reward and mood circuitry located in the corticomesolimbic structures involving the hippocampus, nucleus accumbens, and prefrontal cortex. Repurposing of ketamine for treating TRD provided a new understanding of the pathophysiology of depression, a paradigm shift from monoamine to glutamatergic neurotransmission, thus making it a unique tool to investigate the brain and its complex neurocircuitries.

Pharmacokinetics of ketamine and its major metabolites norketamine, hydroxynorketamine, and dehydronorketamine: a model-based analysis.

BACKGROUND: Recent studies show activity of ketamine metabolites, such as hydroxynorketamine, in producing rapid relief of depression-related symptoms and analgesia. To improve our understanding of the pharmacokinetics of ketamine and metabolites norketamine, dehydronorketamine, and hydroxynorketamine, we developed a population pharmacokinetic model of ketamine and metabolites after i.v. administration of racemic ketamine and the S-isomer (esketamine). Pharmacokinetic data were derived from an RCT on the efficacy of sodium nitroprusside (SNP) in reducing the psychotomimetic side-effects of ketamine in human volunteers. METHODS: Three increasing i.v. doses of esketamine and racemic ketamine were administered to 20 healthy volunteers, and arterial plasma samples were obtained for measurement of ketamine and metabolites. Subjects were randomised to receive esketamine/SNP, esketamine/placebo, racemic ketamine/SNP, and racemic ketamine/placebo on four separate occasions. The time-plasma concentration data of ketamine and metabolites were analysed using a population compartmental model approach. RESULTS: The pharmacokinetics of ketamine and metabolites were adequately described by a seven-compartment model with two ketamine, norketamine, and hydroxynorketamine compartments and one dehydronorketamine compartment with metabolic compartments in-between ketamine and norketamine, and norketamine and dehydronorketamine main compartments. Significant differences were found between S- and R-ketamine enantiomer pharmacokinetics, with up to 50% lower clearances for the R-enantiomers, irrespective of formulation. Whilst SNP had a significant effect on ketamine clearances, simulations showed only minor effects of SNP on total ketamine pharmacokinetics. CONCLUSIONS: The model is of adequate quality for use in future pharmacokinetic and pharmacodynamic studies into the efficacy and side-effects of ketamine and metabolites. CLINICAL TRIAL REGISTRATION: Dutch Cochrane Center 5359.

Distinct cognitive and discriminative stimulus effects of ketamine enantiomers in rats.

Although (S)-ketamine was approved for use in treatment-resistant depression in 2019, new preclinical findings suggest that (R)-ketamine might produce better efficacy and tolerability relative to (S)-ketamine. Here we evaluated the effects of (R)-, (S)-, and (R,S)-ketamine on executive functions as measured in the attentional set shifting task (ASST) and on their discriminative stimulus effects in rats. Earlier data demonstrated that cognitive flexibility is compromised by (R,S)-ketamine, but the effects of enantiomers in rats are unknown. Separate cohorts of rats were tested in ASST and trained to discriminate either (R,S)-ketamine, (S)-ketamine, or (R)-ketamine (all at 10 mg/kg) from saline; in order to maintain the discrimination, a higher (R)-ketamine dose (17.5 mg/kg) was subsequently instituted. In ASST, all three forms increased the trials to criterion measure at reversal learning and extra-dimensional set-shifting phases. However, in contrast to (R)- and (S)-ketamine, (R,S)-ketamine prolonged the mean time to complete a single trial during early stages, suggesting increased reaction time, and/or unspecific side-effects related to motor or motivational impairments. In the drug discriminations, all rats acquired their respective discriminations between drug and saline. In (R,S)-ketamine-trained rats, (R)-ketamine and (S)-ketamine only partially substituted for the training dose of (R,S)-ketamine. Further, (R)-ketamine did not fully substitute in rats trained to (S)-ketamine. The data suggest more serious cognitive deficits produced by (R,S)-ketamine than its enantiomers. Furthermore, (R,S)-ketamine and its isomers share overlapping but not isomorphic discriminative stimulus effects predicting distinct subjective responses to (R)- vs. (S)-ketamine in humans.

Decreased bone mineral density in ovariectomized mice is ameliorated after subsequent repeated intermittent administration of (R)-ketamine, but not (S)-ketamine.

AIM: Depression is a common symptom in people with osteoporosis. (R)-ketamine produced greater potency and longer-lasting antidepressant-like actions than (S)-ketamine in rodents. Here, we examined the effects of two ketamine enantiomers on the reduced bone mineral density (BMD) in the ovariectomized (OVX) mice which is an animal model of postmenopausal osteoporosis. METHODS: Female ddY mice were OVX or sham-operated. Subsequently, saline (10 mL/kg/d, twice weekly), (R)-ketamine (10 mg/kg/d, twice weekly), or (S)-ketamine (10 mg/kg/d, twice weekly) was administered intraperitoneally into OVX or sham mice for the 6 weeks. The femur from all mice was collected 3 days after the final injection, and BMD in the femur was measured. RESULTS: The reduction of cortical BMD and total BMD in the OVX mice was significantly ameliorated after subsequent repeated intermittent administration of (R)-ketamine, but not (S)-ketamine. CONCLUSION: The study shows that (R)-ketamine can ameliorate the reduced cortical BMD and total BMD in OVX mice. Therefore, (R)-ketamine would be a novel therapeutic drug for women with osteoporosis.

Violence against women and drug-facilitated sexual assault (DFSA): A review of the main drugs.

Sexual violence is a universal phenomenon without restriction to sex, age, ethnicity or social class that causes devastating effects in the physical and mental health spheres, in the short-term and long-term, such as pregnancy, sexually transmitted infections (STI) and greater susceptibility to psychiatric symptoms, especially depression. Some cases of sexual assault and rape are based on the use of so-called drug-facilitated sexual assault (DFSA), which cause victims' loss of consciousness and inability to defend, making them vulnerable to violence. Thus, this article aimed to review the literature on gender violence and the drugs used to facilitate sexual assault, addressing their mechanism of action and pharmacokinetics, as well as drug detection times in human body and types of forensic identification. It is understood that the knowledge of these drugs and their pharmacological and diagnostic mechanisms should be widely disseminated, especially about sensitivity tests and the time the drug remains in the body, which would validate the promotion of evidence to prove abuse, and, thus, being able to give a promising outcome to cases of aggression, which is extremely beneficial for women.