Ketamine

GluN2A: A Promising Target for Developing Novel Antidepressants

BACKGROUND

Depression is a heterogeneous disorder with high morbidity and disability rates that poses serious problems regarding mental health care. It is now well established that N-methyl D-aspartate receptor (NMDAR) modulators are being increasingly explored as potential therapeutic options for treating depression, although relatively little is known about their mechanisms of action. NMDARs are glutamate-gated ion channels that are ubiquitously expressed in the central nervous system (CNS), and they have been shown to play key roles in excitatory synaptic transmission. GluN2A, the predominant Glu2N subunit of functional NMDARs in neurons, is involved in various physiological processes in the CNS and is associated with diseases such as anxiety, depression, and schizophrenia. However, the role of GluN2A in the pathophysiology of depression has not yet been elucidated.

METHODS

We reviewed several past studies to better understand the function of GluN2A in depression. Additionally, we also summarized the pathogenesis of depression based on the regulation of GluN2A expression, particularly its interaction with neuroinflammation and neurogenesis, which has received considerable critical attention and is highly implicated in the onset of depression.

RESULTS

These evidence suggests that GluN2A overexpression impairs structural and functional synaptic plasticity, which contributes to the development of depression. Consequently, this knowledge is vital for the development of selective antagonists targeting GluN2A subunits using pharmacological and molecular methods.

CONCLUSIONS

Specific inhibition of the GluN2A NMDAR subunit is resistant to chronic stress-induced depressive-like behaviors, making them promising targets for the development of novel antidepressants.

Ketamine-Induced Cystitis: A Comprehensive Review of the Urologic Effects of This Psychoactive Drug

Ketamine is a common medical anesthetic and analgesic but is becoming more widely used as a recreational drug. Significant side effects on the urinary tract are associated with frequent recreational ketamine use most notably ketamine-induced cystitis (KIC). Regular ketamine consumption has been shown to increase the risk of cystitis symptoms by 3- to 4-fold, and cessation of ketamine use is usually associated with improvement of symptoms. Common KIC-related problems are urinary pain and discomfort, bladder epithelial barrier damage, reduced bladder storage and increased pressure, ureter stenosis, and kidney failure, all of which significantly impact patients' quality of life. Furthermore, it becomes a vicious cycle when KIC patients attempt to manage their urinary pain with increased ketamine use. The precise pathophysiology of KIC is still unknown but several theories exist, most of which highlight the inflammatory signaling pathways leading to bladder epithelium damage due to presence of ketamine in the urine. Empirical treatment options for KIC are available and consist of ketamine cessation, noninvasive therapies, and surgery, and should be decided upon based on the time course and severity of the disease. Of note, cessation of use is strongly recommended for all KIC patients, and should be supplemented with motivational interviews and psychological and social support. It is crucial for clinicians to be familiar with KIC diagnosis and treatment, and to be prepared to have informed discussions with ketamine-using patients about the potential health consequences of ketamine.

Extracorporeal Shock Wave Therapy Protected the Functional and Architectural Integrity of Rodent Urinary Bladder against Ketamine-Induced Damage

This study tested the hypothesis that extracorporeal-shock-wave (ECSW) protected the functional and anatomical integrity of rat urinary-bladder against ketamine-induced damage. In in vitro study, the rat bladder smooth muscle cells (RBdSMCs) were categorized into G1 (sham-control), G2 (RBdSMCs + menadione), G3 (RBdSMCs + ECSW) and G4 (RBdSMCs + menadione + ECSW). The results showed protein expressions of oxidative-stress/mitochondrial-damaged biomarkers (NOX-1/NOX-2/oxidized protein/cytosolic-cytochrome-C/cyclophilin-D), inflammatory markers (MyD88/TRAF6/p-IKB-α/NF-κB/TNF-α/IL-6/IL-1ß/MMP-9/iNOS), and cell-stress response signalings (ASK1/p-MKK4/p-MKK7/ERK1/2//p-JNK/p-p38/p-53) were significantly increased in G2 than in G1 and G3, and those were significantly reversed in G4 (all p < 0.0001). Adult-male SD rats (n = 24) were equally categorized into group 1 (sham-control), group 2 (ketamine/30 mg/kg/daily i.p. injection for four weeks), group 3 [ketamine/30 mg/kg + ECSW/optimal energy (0.12 mJ/mm²/120 impulses/at 3 h and days 3/7/14/21/28 after ketamine administration)] and group 4 [(ketamine/30 mg/kg + ECSW/higher energy (0.16 mJ/mm²/120 impulses)] and animals were euthanized by day 42. The results showed the urine levels of pro-inflammatory cytokines (TNF-α/IL-6) were lowest in group 1, highest in group 2 and significantly higher in group 3 than in group 4 at days 1/7/14/28 (all p < 0.0001). The duration of urinary bladder contraction was lowest in group 2, highest in group 1 and significantly higher in group 4 than in group 3, whereas the maximal pressure of urinary bladder exhibited an opposite pattern of bladder contraction among the groups (all p < 0.0001). The histopathological findings of fibrosis/inflammation/keratinization and protein expressions of oxidative-stress/mitochondrial-damaged biomarkers (NOX-1/NOX-2/oxidized protein/cytosolic-cytochrome-C/cyclophilin-D), and inflammatory (TLR-2/TLR-4/MyD88/TRAF6/p-IKB-α/NF-κB/TNF-α/IL-1ß/MMP-9/iNOS) and cell-stress response (ASK1/p-MKK4/p-MKK7/ERK1/2//p-JNK/p-p38) signalings and apoptotic/fibrotic biomarkers (cleaved-caspas3/cleaved-PARB/Smad3/TFG-ß) exhibited an identical pattern of urine proinflammatory cytokine among the groups (all p < 0.0001). ECSW effectively attenuated ketamine-induced bladder damage and dysfunction.

Genitourinary Tissue Engineering: Reconstruction and Research Models

Tissue engineering is an emerging field of research that initially aimed to produce 3D tissues to bypass the lack of adequate tissues for the repair or replacement of deficient organs. The basis of tissue engineering protocols is to create scaffolds, which can have a synthetic or natural origin, seeded or not with cells. At the same time, more and more studies have indicated the low clinic translation rate of research realised using standard cell culture conditions, i.e., cells on plastic surfaces or using animal models that are too different from humans. New models are needed to mimic the 3D organisation of tissue and the cells themselves and the interaction between cells and the extracellular matrix. In this regard, urology and gynaecology fields are of particular interest. The urethra and vagina can be sites suffering from many pathologies without currently adequate treatment options. Due to the specific organisation of the human urethral/bladder and vaginal epithelium, current research models remain poorly representative. In this review, the anatomy, the current pathologies, and the treatments will be described before focusing on producing tissues and research models using tissue engineering. An emphasis is made on the self-assembly approach, which allows tissue production without the need for biomaterials.

Ketamine-induced urological toxicity: potential mechanisms and translation for adults with mood disorders receiving ketamine treatment

Intravenous (IV) ketamine has been shown to have rapid and robust antidepressant effects in adults with treatment-resistant depression (TRD). Urological toxicity has been observed in chronic ketamine abusers as evidenced by dysuria, urgency, and hematuria. The foregoing observation provides the basis for evaluating whether ketamine-induced urological toxicity (KIUT) is associated with sub-anesthetic doses of ketamine (0.5-1.0 mg/kg) in adults with mood disorders. The overarching objective of this article is to identify potential mechanisms of KIUT which appears to be dose and frequency dependent. Available research indicates that high-frequency ketamine is associated with disruption of the urothelial barrier as well as direct ketamine toxicity (i.e., decreased expression of junction proteins) in KIUT of the bladder. Chronic and high-frequency ketamine use is also associated with bladder inflammation mediated via neurogenic and IgE inflammation. Other non-mutually exclusive causes are nerve hyperplasia, hypersensitivity, cell apoptosis, microvascular damage, and overexpression of carcinogenic genes. Notwithstanding the evidence of KIUT in ketamine abusers, there is no evidence that ketamine and/or esketamine treatment in adults with mood disorders is associated with KIUT. However, all patients receiving ketamine/esketamine for mood disorder treatment should be queried about genitourinary symptoms during acute and, where applicable, maintenance dosing.

Long-term outcome in outpatients with depression treated with acute and maintenance intravenous ketamine: A retrospective chart review

BACKGROUND

Little is known about the long-term outcomes of repeated ketamine infusions for depression. We conducted a retrospective chart review to investigate outcomes of maintenance intravenous ketamine treatment at Massachusetts General Hospital.

METHODS

Eighty-five patients with treatment-resistant depression (TRD) who started intravenous ketamine from October 2018 to November 2019 were examined. Symptom severity was evaluated with the 16-item Quick Inventory of Depressive Symptomatology-Self Report scale (QIDS-SR₁₆) at every visit prior to administration. The initial ketamine dose was usually 0.5 mg/kg infused over 40 min. Intravenous ketamine was administered twice-weekly for three weeks in an induction phase, followed by maintenance with a variable administration schedule and dose. Response was defined as a ≥50% reduction in total QIDS-SR₁₆ score from baseline.

RESULTS

Forty (47.1%) of the 85 patients who started treatment discontinued during or right after the induction phase; 3 (3.5%) were still on induction at the time of this report, and 42 (49.4%) transitioned to maintenance after completing induction. Among these patients, 14 (16.5%) discontinued during maintenance and 28 (32.9%) continued on maintenance. The mean ketamine dosage during maintenance was 0.91±0.28 mg/kg. Fifteen out of 82 patients (18.3%) responded to induction treatment and 6 (7.3%) remained in responder status at the time of data analysis during maintenance. Three patients discontinued ketamine due to side-effects.

CONCLUSIONS

Despite the apparently low response rate in QIDS-SR₁₆ scores and considerable out-of-pocket costs, almost half of real-world outpatients with TRD decided to continue with maintenance ketamine treatment due to perceived significant improvement.

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.

What urologists need to know about ketamine-induced uropathy: A systematic review

AIMS

Ketamine is a general anesthetic. Dissociative effects and low cost led ketamine becoming an illegal recreational drug in young adults. Ketamine-induced uropathy (KIU) is one of the complications observed in abusers. This study aimed to provide a systematic literature review on KIU clinical presentation, pathophysiology, and treatments.

METHODS

We performed the literature search in PubMed, Web of Science, Scopus, and Embase using the terms ketamine and bladder. English papers on human and animal studies were accepted.

RESULTS

A total of 75 papers were selected. Regular ketamine users complain about severe storage symptoms and pelvic pain. Hydronephrosis may develop in long-term abusers and is correlated to the contracted bladder, ureteral stenosis, or vesicoureteral reflux due to ureteral involvement and/or bladder fibrosis. Cystoscopy shows ulcerative cystitis. Ketamine in urine might exert direct toxicity to the urothelium, disrupting its barrier function and enhancing cell apoptosis. The presence of ketamine/ions in the bladder wall result in neurogenic/IgE-mediated inflammation, stimulation of the inducible nitric oxide synthase-cytokines-cyclooxygenase pathway with persistent inflammation and fibrosis. Abstinence is the first therapeutic step. Anti-inflammatory drugs, analgesics and anticholinergics, intravesical instillation of hyaluronic acid, hydrodistension and intravesical injection of botulin toxin-A were helpful in patients with early-stage KIU. In patients with end-stage disease, the control of intractable symptoms and the increase of bladder capacity were the main recommendations to perform augmentation enterocystoplasty.

CONCLUSIONS

KIU is becoming a worldwide health concern, which should be taken into account in the differential diagnosis of ulcerative cystitis.

Rapid-acting antidepressant ketamine, its metabolites and other candidates: A historical overview and future perspective

Major depressive disorder (MDD) is one of the most disabling psychiatric disorders. Approximately one-third of the patients with MDD are treatment resistant to the current antidepressants. There is also a significant therapeutic time lag of weeks to months. Furthermore, depression in patients with bipolar disorder (BD) is typically poorly responsive to antidepressants. Therefore, there exists an unmet medical need for rapidly acting antidepressants with beneficial effects in treatment-resistant patients with MDD or BD. Accumulating evidence suggests that the N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine produces rapid and sustained antidepressant effects in treatment-resistant patients with MDD or BD. Ketamine is a racemic mixture comprising equal parts of (R)-ketamine (or arketamine) and (S)-ketamine (or esketamine). Because (S)-ketamine has higher affinity for NMDAR than (R)-ketamine, esketamine was developed as an antidepressant. On 5 March 2019, esketamine nasal spray was approved by the US Food and Drug Administration. However, preclinical data suggest that (R)-ketamine exerts greater potency and longer-lasting antidepressant effects than (S)-ketamine in animal models of depression and that (R)-ketamine has less detrimental side-effects than (R,S)-ketamine or (S)-ketamine. In this article, the author reviews the historical overview of the antidepressant actions of enantiomers of ketamine and its major metabolites norketamine and hydroxynorketamine. Furthermore, the author discusses the other potential rapid-acting antidepressant candidates (i.e., NMDAR antagonists and modulators, low-voltage-sensitive T-type calcium channel inhibitor, potassium channel Kir4.1 inhibitor, negative modulators of γ-aminobutyric acid, and type A [GABA_A ] receptors) to compare them with ketamine. Moreover, the molecular and cellular mechanisms of ketamine's antidepressant effects are discussed.

Effects of unconventional recreational drug use in pregnancy

Recreational drug toxicity is a rapidly evolving aspect in clinical practice. The prevalence of recreational drug abuse in the past decade has achieved an epidemic scale due to invention of new agents and ease of accessibility to the abused drugs. "Unconventional recreational drugs" is the term that includes new psychoactive drugs and medications diverted for recreational goals. Misuse of unconventional recreational drugs during pregnancy can affect both the pregnant woman and the fetus. However, the problems are usually unrecognized and overlooked by healthcare professionals. In this articles, obstetric complications, teratogenicity and neonatal abstinence syndrome from exposure during pregnancy to synthetic cannabinoids, synthetic cathinones, tramadol, kratom, olanzapine, quetiapine, ketamine and ketamine are reviewed. The main purpose is to create awareness about maternal, fetal and neonatal effects of these unconventional recreational drugs, so healthcare professionals will have improved vigilance for these under-recognized issues.

Consensus Guidelines on the Use of Intravenous Ketamine Infusions for Chronic Pain From the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists

BACKGROUND

Over the past 2 decades, the use of intravenous ketamine infusions as a treatment for chronic pain has increased dramatically, with wide variation in patient selection, dosing, and monitoring. This has led to a chorus of calls from various sources for the development of consensus guidelines.

METHODS

In November 2016, the charge for developing consensus guidelines was approved by the boards of directors of the American Society of Regional Anesthesia and Pain Medicine and, shortly thereafter, the American Academy of Pain Medicine. In late 2017, the completed document was sent to the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters, after which additional modifications were made. Panel members were selected by the committee chair and both boards of directors based on their expertise in evaluating clinical trials, past research experience, and clinical experience in developing protocols and treating patients with ketamine. Questions were developed and refined by the committee, and the groups responsible for addressing each question consisted of modules composed of 3 to 5 panel members in addition to the committee chair. Once a preliminary consensus was achieved, sections were sent to the entire panel, and further revisions were made. In addition to consensus guidelines, a comprehensive narrative review was performed, which formed part of the basis for guidelines.

RESULTS

Guidelines were prepared for the following areas: indications; contraindications; whether there was evidence for a dose-response relationship, or a minimum or therapeutic dose range; whether oral ketamine or another N-methyl-D-aspartate receptor antagonist was a reasonable treatment option as a follow-up to infusions; preinfusion testing requirements; settings and personnel necessary to administer and monitor treatment; the use of preemptive and rescue medications to address adverse effects; and what constitutes a positive treatment response. The group was able to reach consensus on all questions.

CONCLUSIONS

Evidence supports the use of ketamine for chronic pain, but the level of evidence varies by condition and dose range. Most studies evaluating the efficacy of ketamine were small and uncontrolled and were either unblinded or ineffectively blinded. Adverse effects were few and the rate of serious adverse effects was similar to placebo in most studies, with higher dosages and more frequent infusions associated with greater risks. Larger studies, evaluating a wider variety of conditions, are needed to better quantify efficacy, improve patient selection, refine the therapeutic dose range, determine the effectiveness of nonintravenous ketamine alternatives, and develop a greater understanding of the long-term risks of repeated treatments.

Substance misuse-related poisoning deaths, England and Wales, 1993–2016

Context

In recent years there has been an increase in the availability of ‘novel psychoactive substances (NPS)’ or ‘legal highs’. In turn, there is concern as to the risks these compounds pose as compared to those posed by traditionally misused substances such as illicit diamorphine (heroin), methadone, cocaine, and amfetamines.

Methods

We reviewed deaths where opiates/opioids, stimulants, hypnosedatives, hallucinogens, or volatile substances were mentioned on the death certificate in England and Wales, 1993–2016 as recorded on the Office for National Statistics drug poisoning deaths database. Deaths were analysed by year of registration of death, age, sex, intent, drug(s) involved, and the presence of alcohol (ethanol).

Results

There were 68,347 drug-related deaths in England and Wales (includes both licit and illicit substances), of which 15,457 were either coded as, or had mention of, drug dependent/non-dependent substance abuse on the death certificate. Opioids, particularly diamorphine/morphine and methadone, featured in most deaths. Diamorphine/morphine-related deaths (17,402) increased from 155 in 1993 to 981 in 2001, and then remained relatively stable until 2010 (791). Thereafter, annual numbers of deaths fell to 579 in 2012, but have since increased to 1,209 (2016). Deaths in the age group 20–29 years declined from 46% (1993), to 13% (2016), whereas in those aged 40–49 years the percentage of deaths increased from 13% (1993) to 33% (2016). Methadone was mentioned in 7,894 deaths (1993–2016). Annual numbers of such deaths increased from 206 to 437, 1993–7, then declined, but have since increased, reaching 413 in 2016. As to age, a similar pattern as to diamorphine/morphine-related deaths is apparent. Annual numbers of deaths involving cocaine (1993–2016: 3,342), reached 235 in 2008, declined, but have since increased (2011: 112, 2016: 371). Annual numbers of deaths involving methylenedioxyamfetamine/ methylenedioxyethamfetamine/ methylenedioxymetamfetamine (‘ecstasy’) (1993–2016: 853), have also increased steadily in recent years (2010; 8, 2016: 65). There were relatively few mentions of ‘novel stimulants’ (1993–2016: 386) on death certificates and such deaths have declined in recent years (2015: 88, 2016: 57). Mephedrone was most frequently mentioned (122), as was para-methoxyamfetamine/ para-methoxymetamfetamine (88). Conversely, although synthetic cannabinoids were mentioned infrequently (1993–2016: 37), such deaths have increased recently (2015: 8, 2016: 26).

Conclusions

Illicit diamorphine (heroin) and methadone continue to be the principal drugs of abuse involved in fatal poisonings in England and Wales. The increase in such deaths in recent years has been largely due to an increase in deaths amongst older users, although the role of potent synthetic opioids such as carfentanil is a cause for concern. Overall, stimulants and related compounds have been implicated in an increasing number of deaths annually. The impact of the plethora of NPS that have appeared in recent years on fatal poisonings may have been mitigated by legislation.

Engineering Tissues without the Use of a Synthetic Scaffold: A Twenty-Year History of the Self-Assembly Method

Twenty years ago, Dr. François A. Auger, the founder of the Laboratory of Experimental Organogenesis (LOEX), introduced the self-assembly technique. This innovative technique relies on the ability of dermal fibroblasts to produce and assemble their own extracellular matrix, differing from all other tissue-engineering techniques that use preformed synthetic scaffolds. Nevertheless, the use of the self-assembly technique was limited for a long time due to its main drawbacks: time and cost. Recent scientific breakthroughs have addressed these limitations. New protocol modifications that aim at increasing the rate of extracellular matrix formation have been proposed to reduce the production costs and laboratory handling time of engineered tissues. Moreover, the introduction of vascularization strategies in vitro permits the formation of capillary-like networks within reconstructed tissues. These optimization strategies enable the large-scale production of inexpensive native-like substitutes using the self-assembly technique. These substitutes can be used to reconstruct three-dimensional models free of exogenous materials for clinical and fundamental applications.