To use or not to use: an update on licit and illicit ketamine use

Targeting N-Methyl-d-Aspartate Receptors in Neurodegenerative Diseases

N-methyl-d-aspartate receptors (NMDARs) are the main class of ionotropic receptors for the excitatory neurotransmitter glutamate. They play a crucial role in the permeability of Ca2+ ions and excitatory neurotransmission in the brain. Being heteromeric receptors, they are composed of several subunits, including two obligatory GluN1 subunits (eight splice variants) and regulatory GluN2 (GluN2A~D) or GluN3 (GluN3A~B) subunits. Widely distributed in the brain, they regulate other neurotransmission systems and are therefore involved in essential functions such as synaptic transmission, learning and memory, plasticity, and excitotoxicity. The present review will detail the structure, composition, and localization of NMDARs, their role and regulation at the glutamatergic synapse, and their impact on cognitive processes and in neurodegenerative diseases (Alzheimer's, Huntington's, and Parkinson's disease). The pharmacology of different NMDAR antagonists and their therapeutic potentialities will be presented. In particular, a focus will be given on fluoroethylnormemantine (FENM), an investigational drug with very promising development as a neuroprotective agent in Alzheimer's disease, in complement to its reported efficacy as a tomography radiotracer for NMDARs and an anxiolytic drug in post-traumatic stress disorder.

Patterns of ketamine use among people with substance use disorder in France: Multisource analysis of the data from the French Addictovigilance Network

BACKGROUND

Due to its psychoactive effects, ketamine has become a drug used for non-medical purpose.

OBJECTIVES

To assess the latest trends in ketamine use among people with substance use disorder and to characterize its clinical complications using complementary health data sources of the French Addictovigilance Network.

METHODS

First, we extracted all reports involving ketamine from 2012 to 2021 from the database of the OPPIDUM program (i.e., a multicentric program conducted in collaboration with hundreds of substance abuse treatment facilities that collects data on drugs used by subjects with substance use disorders). We described the reports globally and the changes from 2012 to 2021. Second, we extracted all cases involving ketamine from July 2020 to December 2022 from the French National Pharmacovigilance Database (BNPV). We identified the cases related to ketamine use among people with substance use disorder and described them.

RESULTS

There was a 2.5-fold increase in the number of ketamine users with substance use disorder in the OPPIDUM program, from 35 (0.7%) subjects in 2012 to 89 (1.7%) subjects in 2021. There was an increase in the proportion of subjects who were daily users, had distress upon discontinuation, and presented addiction. There were 238 cases related to ketamine use among people with substance use disorder in the French National Pharmacovigilance Database from July 2020 to December 2022. Among them, 94 (39.5%) cases involved ketamine use disorder, 20 (8.4%) cases involved urinary tract and kidney symptoms, and 13 (5.5%) cases involved hepatobiliary symptoms.

CONCLUSION

The trend observed over 10 years reflects the growth in ketamine use among people with substance use disorder, although it does not allow to estimate the rates of non-medical use of ketamine in the general population. Ketamine-induced uropathy and cholangiopathy are reported in ketamine users with substance use disorder, especially in case of repeated and/or prolonged use of high doses.

Ketamine in neuropsychiatric disorders: an update

The discovery of ketamine as a rapid-acting antidepressant led to a new era in the development of neuropsychiatric therapeutics, one characterized by an antidepressant response that occurred within hours or days rather than weeks or months. Considerable clinical research supports the use of-or further research with-subanesthetic-dose ketamine and its (S)-enantiomer esketamine in multiple neuropsychiatric disorders including depression, bipolar disorder, anxiety spectrum disorders, substance use disorders, and eating disorders, as well as for the management of chronic pain. In addition, ketamine often effectively targets symptom domains associated with multiple disorders, such as anxiety, anhedonia, and suicidal ideation. This manuscript: 1) reviews the literature on the pharmacology and hypothesized mechanisms of subanesthetic-dose ketamine in clinical research; 2) describes similarities and differences in the mechanism of action and antidepressant efficacy between racemic ketamine, its (S) and (R) enantiomers, and its hydroxynorketamine (HNK) metabolite; 3) discusses the day-to-day use of ketamine in the clinical setting; 4) provides an overview of ketamine use in other psychiatric disorders and depression-related comorbidities (e.g., suicidal ideation); and 5) provides insights into the mechanisms of ketamine and therapeutic response gleaned from the study of other novel therapeutics and neuroimaging modalities.

Molecular and Structural Insight into Adenosine A2A Receptor in Neurodegenerative Disorders: A Significant Target for Efficient Treatment Approach

All biological tissues and bodily fluids include the autacoid adenosine. The P1 class of purinergic receptors includes adenosine receptors. Four distinct G-protein-coupled receptors on the cellular membrane mediate the effects of adenosine, whose cytoplasmic content is regulated by producing/degrading enzymes and nucleoside transporters. A2A receptor has received a great deal of attention in recent years because it has a wide range of potential therapeutic uses. A2B and, more significantly, A2A receptors regulate numerous physiological mechanisms in the central nervous system (CNS). The inferior targetability of A2B receptors towards adenosine points that they might portray a promising medicinal target since they are triggered only under pharmacological circumstances (when adenosine levels rise up to micromolar concentrations). The accessibility of specific ligands for A2B receptors would permit the exploration of such a theory. A2A receptors mediate both potentially neurotoxic and neuroprotective actions. Hence, it is debatable to what extent they play a role in neurodegenerative illnesses. However, A2A receptor blockers have demonstrated clear antiparkinsonian consequences, and a significant attraction exists in the role of A2A receptors in other neurodegenerative disorders. Amyloid peptide extracellular accumulation and tau hyperphosphorylation are the pathogenic components of AD that lead to neuronal cell death, cognitive impairment, and memory loss. Interestingly, in vitro and in vivo research has shown that A2A adenosine receptor antagonists may block each of these clinical symptoms, offering a crucial new approach to combat a condition for which, regrettably, only symptomatic medications are currently available. At least two requirements must be met to determine whether such receptors are a target for diseases of the CNS: a complete understanding of the mechanisms governing A2A-dependent processes and the availability of ligands that can distinguish between the various receptor populations. This review concisely summarises the biological effects mediated by A2A adenosine receptors in neurodegenerative disorders and discusses the chemical characteristics of A2A adenosine receptor antagonists undergoing clinical trials. Selective A2A receptor blocker against neurodegenerative disorders.

Empirical evidence for the neurocognitive effect of nitrous oxide as an adjunctive therapy in patients with treatment resistant depression: A randomized controlled study

Nitrous oxide (N₂O) has demonstrated an antidepressant effect for treatment-resistant depression (TRD), but no studies investigated the effects of N₂O on different cognition domains. This study aimed to test whether N₂O would display pro-cognitive effects. We conducted a double-blinded, placebo-controlled, randomized controlled trial, 44 patients with TRD were randomized to N₂O group (one-hour inhalation of 50% N₂O/50% oxygen) or placebo group (50% air/50% oxygen). Thirty-four patients completed cognitive tests at the pre-treatment phase, 1-week, and 2 weeks post-treatment including subjective cognitive function, processing speed, attention, and executive function. Although the antidepressant effect of N₂O was not significant at 1 week, patients still showed better performance of executive function at 1 week after receiving N₂O compared with the placebo. Moreover, this significant improvement still existed at 1 week after controlling for the change in depressive symptoms over-time. Additionally, no significant difference was observed in subjective cognitive function, processing speed, and attention between these two groups across the 2-week follow-up period. As the first study investigating the treatment effects of N₂O on improving cognitive function in TRD patients, the current study indicated that N₂O has a potential pro-cognitive effect on executive function and this effect might be independent from improvements in depressive symptoms.

Age, Dose, and Locomotion: Decoding Vulnerability to Ketamine in C57BL/6J and BALB/c Mice

Ketamine has been abused as a psychedelic agent and causes diverse neurobehavioral changes. Adolescence is a critical developmental stage but vulnerable to substances and environmental stimuli. Growing evidence shows that ketamine affects glutamatergic neurotransmission, which is important for memory storage, addiction, and psychosis. To explore diverse biological responses, this study was designed to assess ketamine sensitivity in mice of different ages and strains. Male C57BL/6J and BALB/c mice were studied in adolescence and adulthood separately. An open field test assessed motor behavioral changes. After a 30-min baseline habituation, mice were injected with ketamine (0, 25, and 50 mg/kg), and their locomotion was measured for 60 min. Following ketamine injection, the travelled distance and speed significantly increased in C57BL/6J mice between both age groups (p < 0.01), but not in BALB/c mice. The pattern of hyperlocomotion showed that mice were delayed at the higher dose (50 mg/kg) compared to the lower dose (25 mg/kg) of ketamine treatment. Ketamine accentuated locomotor activation in adolescent C57BL/6J mice compared to adults, but not in the BALB/c strain. Here, we show that ketamine-induced locomotor behavior is modulated by dose and age. The discrepancy of neurobehaviors in the two strains of mice indicates that sensitivity to ketamine is biologically determined. This study suggests that individual vulnerability to ketamine's pharmacological responses varies biologically.

The effects of ketamine on viability, primary DNA damage, and oxidative stress parameters in HepG2 and SH-SY5Y cells

Ketamine is a dissociative anaesthetic used to induce general anaesthesia in humans and laboratory animals. Due to its hallucinogenic and dissociative effects, it is also used as a recreational drug. Anaesthetic agents can cause toxic effects at the cellular level and affect cell survival, induce DNA damage, and cause oxidant/antioxidant imbalance. The aim of this study was to explore these possible adverse effects of ketamine on hepatocellular HepG2 and neuroblastoma SH-SY5Y cells after 24-hour exposure to a concentration range covering concentrations used in analgesia, drug abuse, and anaesthesia (0.39, 1.56, and 6.25 µmol/L, respectively). At these concentrations ketamine had relatively low toxic outcomes, as it lowered HepG2 and SH-SY5Y cell viability up to 30 %, and low, potentially repairable DNA damage. Interestingly, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) remained unchanged in both cell lines. On the other hand, oxidative stress markers [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] pointed to ketamine-induced oxidant/antioxidant imbalance.

Occurrence of Z-drugs, benzodiazepines, and ketamine in wastewater in the United States and Mexico during the Covid-19 pandemic

Z-drugs, benzodiazepines and ketamine are classes of psychotropic drugs prescribed for treating anxiety, sleep disorders and depression with known side effects including an elevated risk of addiction and substance misuse. These drugs have a strong potential for misuse, which has escalated over the years and was hypothesized here to have been exacerbated during the COVID-19 pandemic. Wastewater-based epidemiology (WBE) constitutes a fast, easy, and relatively inexpensive approach to epidemiological surveys for understanding the incidence and frequency of uses of these drugs. In this study, we analyzed wastewater (n = 376) from 50 cities across the United States and Mexico from July to October 2020 to estimate drug use rates during a pandemic event. Both time and flow proportional composite and grab samples of untreated municipal wastewater were analyzed using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry to determine loadings of alprazolam, clonazepam, diazepam, ketamine, lorazepam, nordiazepam, temazepam, zolpidem, and zaleplon in raw wastewater. Simultaneously, prescription data of the aforementioned drugs were extracted from the Medicaid database from 2019 to 2021. Results showed high detection frequencies of ketamine (90 %), lorazepam (87 %), clonazepam (76 %) and temazepam (73 %) across both Mexico and United States and comparatively lower detection frequencies for zaleplon (22 %), zolpidem (9 %), nordiazepam (<1 %), diazepam (<1 %), and alprazolam (<1 %) during the pandemic. Average mass consumption rates, estimated using WBE and reported in units of mg/day/1000 persons, ranged between 62 (temazepam) and 1100 (clonazepam) in the United States. Results obtained from the Medicaid database also showed a significant change (p < 0.05) in the prescription volume between the first quarter of 2019 (before the pandemic) and the first quarter of 2021 (pandemic event) for alprazolam, clonazepam and lorazepam. Study results include the first detections of zaleplon and zolpidem in wastewater from North America.

Mifepristone (RU-486®) as a Schedule IV Controlled Drug—Implications for a Misleading Drug Policy on Women’s Health Care

Background: Mifepristone (RU-486) has been approved for abortion in Taiwan since 2000. Mifepristone was the first non-addictive medicine to be classified as a schedule IV controlled drug. As a case of the “misuse” of “misuse of drugs laws,” the policy and consequences of mifepristone-assisted abortion for pregnant women could be compared with those of illicit drug use for drug addicts. Methods: The rule-making process of mifepristone regulation was analyzed from various aspects of legitimacy, social stigma, women’s human rights, and access to health care. Results and Discussion: The restriction policy on mifepristone regulation in Taiwan has raised concerns over the legitimacy of listing a non-addictive substance as a controlled drug, which may produce stigma and negatively affect women’s reproductive and privacy rights. Such a restriction policy and social stigma may lead to the unwillingness of pregnant women to utilize safe abortion services. Under the threat of the COVID-19 pandemic, the US FDA’s action on mifepristone prescription and dispensing reminds us it is time to consider a change of policy. Conclusions: Listing mifepristone as a controlled drug could impede the acceptability and accessibility of safe mifepristone use and violates women’s right to health care.

The One Health vision requires veterinarians and physicians to collaborate to prevent bioethical challenges created by restricted access to ketamine in low- and middle-income countries

The One Health approach asserts that the health of animals and people is closely connected. Under this approach, the CDC and AVMA work globally to attain optimal health outcomes for both animals and humans. One facet of optimal health involves access to safe and effective anesthetics and analgesics. The anesthetic and analgesic drug ketamine possesses unique properties that make it particularly important for both veterinary and human patients in low- and middle-income countries (LMICs). These properties include its portability and stability, low cost, ease of administration, and wide therapeutic margin. China advocates regularly to the United Nations for global scheduling of ketamine as a controlled substance. However, this would disproportionately restrict access to ketamine in LMICs, imposing bioethical challenges related to animal patients, human patients, and communities. In alignment with the One Health vision, opposing global scheduling of ketamine in LMICs creates a unique opportunity for collaboration between veterinarians and physicians in LMICs and high-income countries to prevent these bioethical challenges.

Ketamine: from prescription anaesthetic to New Psychoactive Substance

Discovered in the United States of America (USA) in the 1960s, ketamine was introduced as an anaesthetic drug to specifically replace phencyclidine. Briefly, the substance moved from the medical world to recreational users, since it was discovered that intense psychedelic experiences were obtained with dosages lower than those prescribed for anesthesia. At the end of the 90's, circulated in London nightclubs as a drug itself and as counterfeit 3,4-methylenedioxymethamphetamine tablets. In 1997, the Drug Enforcement Administration (DEA) alerted the United States (US) government to the increasing diffusion of ketamine in American 'clubs', and in 1999, the substance was added to Schedule III of drugs controlled by federal authorities. In 2002, ketamine epidemics moved to Europe, and the European Monitoring Centre for Drugs and Drug Addiction carried out a risk assessment monitoring of the phenomenon. An estimated ninety-nine percent of all global ketamine seizures occurred in Asia. Its growing popularity is due to the fact that this new psychoactive substance is cheaper than other stimulants such as MDMA that the amount used for recreational purposes does not cause respiratory depression and its legal use as a drug makes it widely available for a diversion towards illicit markets. Nevertheless, acute intoxication and several deaths have been related to exclusive ketamine use both in Europe and internationally. Since 2015, there has been and increasing rise of the illicit ketamine market and currently the drug is being used with unprecedented peaks and a consequent significant increase in seizures and clinical cases worldwide.

Ketamine use disorder: preclinical, clinical, and neuroimaging evidence to support proposed mechanisms of actions

Ketamine, a noncompetitive NMDA receptor antagonist, has been exclusively used as an anesthetic in medicine and has led to new insights into the pathophysiology of neuropsychiatric disorders. Clinical studies have shown that low subanesthetic doses of ketamine produce antidepressant effects for individuals with depression. However, its use as a treatment for psychiatric disorders has been limited due to its reinforcing effects and high potential for diversion and misuse. Preclinical studies have focused on understanding the molecular mechanisms underlying ketamine's antidepressant effects, but a precise mechanism had yet to be elucidated. Here we review different hypotheses for ketamine's mechanism of action including the direct inhibition and disinhibition of NMDA receptors, AMPAR activation, and heightened activation of monoaminergic systems. The proposed mechanisms are not mutually exclusive, and their combined influence may exert the observed structural and functional neural impairments. Long term use of ketamine induces brain structural, functional impairments, and neurodevelopmental effects in both rodents and humans. Its misuse has increased rapidly in the past 20 years and is one of the most common addictive drugs used in Asia. The proposed mechanisms of action and supporting neuroimaging data allow for the development of tools to identify 'biotypes' of ketamine use disorder (KUD) using machine learning approaches, which could inform intervention and treatment.

Long-term safety of ketamine and esketamine in treatment of depression

INTRODUCTION

Ketamine is an NMDA receptor antagonist that can produce rapid-acting antidepressant effects. Esketamine (Spravato), the S-enantiomer of racemic ketamine, was approved by the FDA for treatment-resistant depression in 2019. Here we review what is known about the long-term safety of both racemic ketamine and esketamine as therapies for psychiatric disorders.

AREAS COVERED

In this article, we conducted a safety review of ketamine and esketamine. In looking at ketamine and esketamine long-term safety effects, we considered data available from experimental studies and several phase-three clinical trials.

EXPERT OPINION

Based on available data, the most common side effects of ketamine/esketamine are generally transient, mild, and self-limited. These include dissociation, nausea, headache, elevated heart rate, and blood pressure. Treatment with esketamine may lead to an increased risk of lower urinary tract symptoms, such as dysuria or urgency. However, severe bladder pathology has not been reported among patients receiving doses of esketamine/ketamine in line with prescribing guidelines for depression. There is considerable data that ketamine at high doses can lead to long-term impairments in cognition. However, the esketamine clinical trials found that cognition generally remains stable or improves over time, suggesting that when used appropriately, there is no increased risk of cognitive impairment.

Optimized Clinical Strategies for Treatment-Resistant Depression: Integrating Ketamine Protocols with Trauma- and Attachment-Informed Psychotherapy

Strategically timed trauma- and attachment-informed psychotherapy to address underlying emotional wounds, paired with ketamine administered in precision-calibrated doses to ensure high-entropy brain states, may be key to improving the quality and duration of ketamine’s therapeutic efficacy for treatment-resistant depression. This approach optimizes the opportunities for change created by ketamine’s known effects as a rapid antidepressant that stimulates synaptogenesis, normalizes neural connectivity and coherence, enhances neuroplasticity, reduces inflammation, and induces high-entropy brain states with associated subjective psychedelic experiences. Ketamine, a non-selective N-methyl-D-aspartate (NMDA) receptor antagonist is a safe, effective, fast-acting dissociative anesthetic that, as a standalone treatment, also exhibits rapid sustained antidepressant effects, even in many patients with treatment-resistant depression. A prior history of developmental trauma and attachment injuries are known primary factors in the etiology of treatment resistance in depression and other mental disorders. Thus, the adjunct of targeted psychotherapy attuned to trauma and attachment injuries may enhance and prolong ketamine efficacy and provide an opportunity for lasting therapeutic change. Psychotherapy engagement during repeated ketamine sessions for patient safety and integration of altered states, paired with separate individualized psychotherapy-only sessions timed 24–48 h post ketamine induction, takes advantage of peak ketamine-induced dendritic spine growth in the prefrontal cortex and limbic system, and normalized network connectivity across brain structures. This strategically timed paired-session approach also exploits the therapeutic potential created by precision-calibrated ketamine-linked high-entropy brain states and associated psychedelic experiences that are posited to disrupt overly rigid maladaptive thoughts, behaviors, and disturbing memories associated with treatment-resistant depression; paired sessions also support integration of the felt sense of happiness and connectivity associated with psychedelic experiences.

Ketamine use in relation to depressive symptoms among high school seniors

BACKGROUND AND OBJECTIVES

Ketamine is efficacious in treating treatment-resistant depression in medical settings and the drug was approved for such use by the US Federal Drug Administration in 2019. However, little is known about how use outside of medical settings relates to depression. We determined whether recreational ketamine use, relative to the use of other drugs, is related to the current experience of depression among adolescents.

METHODS

We examined data from the 2016 to 2019 Monitoring the Future nationally representative survey of high school seniors in the United States (N = 15,673). We determined how past-year drug use and frequency of past-year drug use were associated with students reporting a high level of current depressive symptoms relative to other students.

RESULTS

Ketamine use was associated with highest risk for a high level of depression (aPR = 1.55, 95% confidence interval [CI]: 1.24-1.94), followed by use of cannabis (aPR = 1.29, 95% CI: 1.19-1.39), and nonmedical use of tranquilizers (aPR = 1.22, 95% CI: 1.04-1.44) and amphetamine (aPR = 1.17, 95% CI: 1.01-1.34). Alcohol use was associated with decreased risk (aPR = 0.92, 95% CI: 0.85-0.99). With respect to frequency of past-year use, more frequent use of ketamine and cannabis was associated with increased risk for a high level of depression in a dose-response-like manner, with past-year use of ketamine and cannabis ≥10 times associated with increased risk for depression by 70% and 40%, respectively.

DISCUSSION AND CONCLUSIONS

Past-year recreational ketamine use is a risk factor for reporting current depression than most other drugs.

SCIENTIFIC SIGNIFICANCE

This was the first study to compare the risk of use of various drugs in relation to depression.

Clinical and behavior characteristics of individuals who used ketamine

This study aims to depict and compare clinical characteristics and risk behavior among groups of individuals using ketamine, polydrugs or smoking cigarette. A total of 185 drug-using participants and 49 smokers participated in this study. A cross-sectional interview was used to collect information on demographics, drug- and sex-related behaviors, HIV serostatus, lower urinary tract symptoms (LUTS), behavioral dispositions. N-back memory test was used to measure short-term memory. Result shows that 10 participants (5.41%) were HIV positive and 14 (7.57%) having LUTS. Individuals with ketamine and polydrugs use have significantly worse drug-related problem than cigarette smokers. Compared to cigarette smokers and ketamine users, individuals with polydrug users scored significantly higher on impulsivity measures. Cigarette smokers performed significantly better than the other two groups on the memory tests. A few patients had been infected with HIV and diagnosed with LUTS. Findings support that memory on short term recalls of patients with ketamine use might be impaired. Study findings warrants the necessarily of further study on influences of using ketamine.

Non-parenteral Ketamine for Depression: A Practical Discussion on Addiction Potential and Recommendations for Judicious Prescribing

Intravenous (IV) ketamine is increasingly used off-label at subanesthetic doses for its rapid antidepressant effect, and intranasal (IN) esketamine has been recently approved in several countries for treating depression. The clinical utility of these treatments is limited by a paucity of publicly funded IV ketamine and IN esketamine programs and cost barriers to private treatment programs, as well as the drug cost for IN esketamine itself, which makes generic ketamine alternatives an attractive option. Though evidence is limited, use of non-parenteral racemic ketamine formulations (oral, sublingual, and IN) may offer more realistic access in less rigidly supervised settings, both for acute and maintenance treatment in select cases. However, the psychiatric literature has repeatedly cautioned on the addictive potential of ketamine and raised caution for both less supervised and longer-term use of ketamine. To date, these concerns have not been discussed in view of available evidence, nor have they been discussed within a broader clinical context. This paper examines the available relevant literature and suggests that ketamine misuse risks appear not dissimilar to those of other well-established and commonly prescribed agents with abuse potential, such as stimulants or benzodiazepines. As such, ketamine prescribing should be considered in a similar risk/benefit context to balance patient access and need for treatment with concern for potential substance misuse. Our consortium of mood disorder specialists with significant ketamine prescribing experience considers prescribing of non-parenteral ketamine a reasonable clinical treatment option in select cases of treatment-resistant depression. This paper outlines where this may be appropriate and makes practical recommendations for clinicians in judicious prescribing of non-parenteral ketamine.

The impact of Taiwan's implementation of a nationwide harm reduction program in 2006 on the use of various illicit drugs: trend analysis of first-time offenders from 2001 to 2017

Background

After implementing a nationwide harm reduction program in 2006, a dramatic decline in the incidence of human immunodeficiency virus (HIV) infection among people with injection drug use (IDU) was observed in Taiwan. The harm reduction program might have sent out the message discouraging the choice of IDU among illicit drug users in early stage. Based on the yearly first-time offense rates from 2001 to 2017, this study aimed to examine (1) whether the nationwide implementation of the harm reduction program in 2006 led to changes in first-time offenders’ use of heroin; (2) whether the intervention had a similar effect on the use of other illicit drugs; and (3) whether the effect of the intervention was limited to the first-time offenders of young age groups.

Methods

Yearly first-time illicit-drug offense rates from 2001 to 2017 in Taiwan were derived from two national databases for drug arrests that were verified using urine tests: the Criminal Record Processing System on Schedule I/II Drugs and the Administrative Penalty System for Schedule III/IV Substances. A hierarchy of mutually exclusive categories of drug uses was defined by the drug with the highest schedule level among those tested positive in an arrest. Segmented regression analyses of interrupted time series were used to test for the impact of the 2006 intervention.

Results

There was a decrease of 22.37 per 100,000 in the rate for heroin but no detectable level changes in that for methamphetamine or ecstasy after the 2006 intervention in Taiwan. There were baseline decreasing trends in the first-time offense rate from 2001 to 2017 for heroin and ecstasy and an increasing trend for methamphetamine, with the slopes not altered by the 2006 intervention. The postintervention decrease in the first-time offense rate for heroin was detectable among offenders less than 40 years old.

Conclusions

Our results indicate a diffusion effect of the 2006 intervention on decreasing heroin use among young offenders and have policy implications for better prevention and treatment for different age groups.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12954-021-00566-5.

Analysis of drug residue in needle-exchange syringes in Washington, D.C

For the first time in Washington, D.C., an analysis of drug residue from used needle-exchange syringes has been performed. This analysis is part of a larger initiative to understand the District of Columbia's illicit drug supply and its intravenous (IV) user's consumption trends as our nation faces the opioid epidemic. The goal of this study is to develop a more comprehensive monitoring program that provides real-time analysis necessary for public health organizations, in addition to providing initial observations of drugs detected. A total of 1187 syringes were analyzed over a period of nine months. Of these, 732 syringes (61.7%) were confirmed to contain a controlled dangerous substance (CDS). Fentanyl was detected in 490 syringes, the most observed CDS in all syringes analyzed. Heroin was the second most detected CDS, observed in 192 syringes. The third most detected CDS was cocaine, which was observed in 132 syringes, followed by the fourth most detected CDS, methamphetamine, observed in 82 syringes. Novel findings of this study include the first reported detections of methamphetamine, synthetic cathinones, and synthetic cannabinoids in used syringes in D.C. Ninety-seven syringes that contained no CDS contained a non-controlled substance of interest, such as diphenhydramine, xylazine, and etizolam. One limitation of this study is that this method cannot determine whether mixtures present in syringes stem from mixtures present prior to injection, back-to-back usage, or sharing of needles. This preliminary study illustrates the strength of surveillance to monitor drug trends and can be used to detect emerging novel dangerous substances in the future.

Neurofilament light chain as novel blood biomarker of disturbed neuroaxonal integrity in patients with ketamine dependence

OBJECTIVES

Chronic and heavy ketamine use has been associated with persistent neurocognitive impairment and structural brain abnormalities. Blood levels of neurofilament light chain (NFL) was recently proposed as a measure of axonal integrity in several neuropsychiatric disorders. We aimed to characterise the axonal neurotoxicity of chronic ketamine use and its relationship to relevant clinical outcomes.

METHODS

We enrolled 65 treatment-seeking ketamine-dependent patients (55 males and 10 females) and 60 healthy controls (51 males and 9 females). Blood NFL levels measured by single molecule array (SiMoA) immunoassay. We compared NFL levels between groups and used regression analyses to identify clinical variables related to NFL levels.

RESULTS

Ketamine-dependent patients had significantly higher NFL levels compared to controls (p < 0.001). A multivariate regression showed that age (p < 0.05) and lifetime history of major depressive disorder (MDD) (p < 0.01) predicted high NFL blood levels in patients. Subsequent group comparisons showed that specifically ketamine-dependent patients with a lifetime history of MDD had significantly increased NFL levels than those without (p < 0.05).

CONCLUSIONS

These results suggest substantial neuroaxonal alterations following chronic and heavy ketamine use. The pronounced increase of NFL levels in the MDD subgroup warrants further investigation of a potential neuroaxonal vulnerability of depressed patients to ketamine.

Recreational ketamine-related deaths notified to the National Programme on Substance Abuse Deaths, England, 1997-2019

BACKGROUND

Ketamine is a phencyclidine derivative with dissociative anaesthetic properties. Increasing numbers of individuals in England take ketamine recreationally. Information on deaths arising from such use in England is presented.

METHODS

Cases were extracted on 31 January 2020 from the National Programme on Substance Abuse Deaths database, based on text searches of the cause of death, coroner's verdict and positive toxicology results for the terms 'ketamine' or 'norketamine'.

FINDINGS

During 1997-2005, there were <5 deaths p.a. in which ketamine was implicated. Numbers increased until 2009 (21), plateauing until 2016; thereafter, deaths have risen to about 30 p.a. Decedents' characteristics (N = 283): male 84.1%, mean age 31.2 (SD 10.0) years, employed 56.5%, drug use history 79.6% and living with others 60.3%. Ketamine was detected with other substances in most cases. Main (74.6%) underlying cause of death was accidental poisoning. Ketamine may have impaired judgement in other cases.

CONCLUSIONS

Although controlled, recreational ketamine use and related fatalities continue to increase. Consumers need to be more aware of the potentially fatal risks they face.

Increased Nectin-4 levels in chronic ketamine abusers and the relationship with lower urinary tract symptoms

Persistent ketamine use causes susceptibility to addiction and bladder toxicity. We examined the association of lower urinary tract symptoms and levels of Nectin-4, a member of the cell adhesion molecules that is essential for maintaining the urothelium barrier in chronic ketamine abusers. We measured the plasma levels of Nectin-4 in 88 patients with ketamine dependence and 69 controls. Patients with ketamine dependence were assessed for ketamine use variables, psychological symptoms, and lower urinary tract symptoms. We found Nectin-4 levels were increased in ketamine-dependent patients compared to the controls (p < 0.0001). Patients with urinary tract symptoms exhibited lower Nectin-4 levels than those without (p = 0.021). Our results suggest an up-regulation of Nectin-4 following chronic and heavy ketamine use. Patients with ketamine dependence with a compromised upregulation of Nectin-4 are likely to have more severe urinary tract symptoms. The mechanisms underlying the involvement of Nectin-4 in ketamine addiction and bladder toxicity warrant future investigation.

Gender Differences in Depression and Quality of Life in Current and Abstinent Ketamine Users

Ketamine use has become of increasing concern because it has spread in many parts of the world during the past few years. Substance users usually have depression and a lower quality of life (QoL). The aim of this study was to explore depression and QoL in ketamine users, and to further examine the role of gender in relation to differences in depression and QoL in ketamine users. This study recruited 204 current ketamine users, 102 abstinent ketamine users and 102 healthy controls. The demographic data, severity of depression and QoL were recorded. Analysis of Variance (ANOVA) was employed to compare the associations of ketamine use status with depression and QoL. Gender differences were examined by moderator analysis. The current ketamine users with and without ketamine use disorder, in addition to the abstinent ketamine users with ketamine use disorder, have more severe depression and a lower QoL than healthy controls. There were significant gender differences in depression and QoL in abstinent ketamine users with ketamine use disorder. Ketamine users have more severe depression and a lower QoL. In particular, depression and a lower QoL are still prominent in abstinent ketamine users. The gender differences in depression and QoL are significant in abstinent ketamine users.

First-time offenders for recreational ketamine use under a new penalty system in Taiwan: incidence, recidivism and mortality in national cohorts from 2009 to 2017

BACKGROUND AND AIMS

Ketamine has become a new recreational drug of choice among young people in parts of Asia. Using national databases in Taiwan, this study aimed to (1) examine the yearly trend in the ketamine offence rate over time; (2) estimate the 3-year risk of drug-related re-offence and its correlates among the first-time offenders; and (3) estimate the 3-year standardized mortality ratio (SMR) among the first-time offenders.

DESIGN, SETTING AND PARTICIPANTS

Retrospective cohort studies of offenders for recreational ketamine use in a penalty system initiated in 2009. Offenders for recreational ketamine use were identified from the Administrative Penalty System for Schedule III/IV Substances database from 2009 to 2017, and the re-offence rate and mortality among first-time offenders were assessed via record-linkage within the database as well as with both the criminal drug offence database and the national mortality database. The cohort from 2009 to 2016 (n = 39 178) was used for the recidivism analysis and the cohort from 2009 to 2013 (n = 25 357) was used for the 3-year SMR analysis.

MEASUREMENTS

Recidivism was estimated using survival analysis of the event as re-arrest for using ketamine, more serious illicit drugs (Schedules I/II), or any illicit drugs (ketamine or Schedules I/II). SMRs were estimated for overall and cause-specific death within 3 years after the first offence for ketamine use.

FINDINGS

The age-standardized rates for both prevalent (1.38 per 1000) and first-time offenders (0.65 per 1000) peaked in 2013 and then decreased steadily. The 3-year risk of re-offence was 33.85% [95% confidence interval (CI) = 33.23-34.47%) for ketamine use and 39.52% (95% CI = 39.00-40.04%) for any illicit drug use. These first-time offenders had an SMR of 4.9 (95% CI = 4.3-5.4) for overall mortality, 2.1 (95% CI = 1.6-2.7) for natural deaths and 7.6 (95% CI = 6.7-8.6) for unnatural deaths.

CONCLUSIONS

Recreational ketamine use in Taiwan appears to lead not only to high risk for drug-related re-offence but also to excess mortality.

Harm related to recreational ketamine use and its relevance for the clinical use of ketamine. A systematic review and comparison study

BACKGROUNDS

Ketamine is a dissociative anesthetic that is currently considered for several new indications.

AIM

To deduce the safety of long-term ketamine treatment using the harm of heavy recreational (non-medical) ketamine use as a proxy for maximal possible harm of ketamine treatment.

METHODS

Systematic literature review according to PRISMA guidelines to identify controlled studies on ketamine-related harm in heavy recreational ketamine users. Results were compared with serious adverse events (SAEs) in patients treated with ketamine according to three systematic reviews considering dosing regimen and cumulative dose.

RESULTS

The systematic search yielded 25 studies. Heavy recreational ketamine use can escalate to ketamine dependency and was often dose-dependently associated with other SAEs, including cognitive and mental disorders, and gastrointestinal and urinary tract symptoms, which disappeared upon marked reduction of ketamine use. Heavy ketamine users have a much higher cumulative exposure to ketamine than ketamine treated patients (>90 times), which may explain why SAEs in the clinical context are mostly mild and reversible and why ketamine dependence was not reported in these patients.

CONCLUSION

Treatment of patients with ketamine is not associated with ketamine dependency or SAEs. However, caution is needed since data on long-term clinical ketamine use with a long-term follow-up is lacking.

Therapeutic potential of ketamine for alcohol use disorder

Excessive alcohol consumption is involved in 1/10 of deaths of U.S. working-age adults and costs the country around $250,000,000 yearly. While Alcohol Use Disorder (AUD) pathology is complex and involves multiple neurotransmitter systems, changes in synaptic plasticity, hippocampal neurogenesis, and neural connectivity have been implicated in the behavioral characteristics of AUD. Depressed mood and stress are major determinants of relapse in AUD, and there is significant comorbidity between AUD, depression, and stress disorders, suggesting potential for overlap in their treatments. Disulfiram, naltrexone, and acamprosate are current pharmacotherapies for AUD, but these treatments have limitations, highlighting the need for novel therapeutics. Ketamine is a N-methyl-D-Aspartate receptor antagonist, historically used in anesthesia, but also affects other neurotransmitters systems, synaptic plasticity, neurogenesis, and neural connectivity. Currently under investigation for treating AUDs and other Substance Use Disorders (SUDs), ketamine has strong support for efficacy in treating clinical depression, recently receiving FDA approval. Ketamine's effect in treating depression and stress disorders, such as PTSD, and preliminary evidence for treating SUDs further suggests a role for treating AUDs. This review explores the behavioral and neural evidence for treating AUDs with ketamine and clinical data on ketamine therapy for AUDs and SUDs.

An Integrative Approach to Ketamine Therapy May Enhance Multiple Dimensions of Efficacy: Improving Therapeutic Outcomes With Treatment Resistant Depression

Research over the last two decades has established ketamine as a safe, effective, fast-acting, and sustained antidepressant that significantly reduces adverse symptoms associated with depression, even in patients who are treatment resistant. Much of this research has evolved within the framework of several independent branches of scientific inquiry: in addition to the study of ketamine is a non-selective NMDAR antagonist with rapid antidepressant effects, it has also been found effective as a psychoplastogen that stimulates synaptogenesis and increases neuroplasticity, as a powerful anti-inflammatory that may improve inflammation-related depressive symptoms, as a substance that induces beneficial high entropy brain states, and as a subjectively impactful psychedelic agent. Each branch of inquiry has generated independent evidence of ketamine's efficacy but has advanced without substantive coordination or communication with other lines of inquiry. Integrative research that considers these branches of research together may lead toward a better understanding of ketamine's effects and improved treatment protocols and clinical outcomes. Such an overview can inform more comprehensive patient care through: (a) informed patient psychoeducation that encompasses all of ketamine's mechanisms of action; (b) calibration of optimal dosage to ensure induction and maintenance of high entropy brain states during each ketamine session utilizing EEG measurement; (c) Improved management of emergence side effects through proper care for set and setting; (d) inclusion of pre-selected appropriate music to enhance the emotional experience; (e) increased monitoring of ketamine effects on cortical activity, inter-hemispheric imbalance, and inflammation-related levels of cytokines to further improvements in ketamine protocols; and (f) appropriate timing of any adjunctive psychotherapy sessions to coincide with peak neurogenesis at 24-48 h post ketamine treatment.

Sleep quality among individuals with ketamine use and the mediating role of craving

Sleep problems are common in Taiwan. Poor sleep may be associated with many illnesses, including substance use disorders. Ketamine use disorder has significantly increased in Taiwan in recent years and may lead to physical and cognitive problems. Craving for ketamine is a risk factor for ketamine use and relapse, and poor sleep quality may increase craving. This study aimed to explore the mediating effects of craving on the relationship between poor sleep quality and ketamine use. Demographic data, sleep quality, severity of dependence and craving were recorded for current ketamine users and abstinent ketamine users. Mediation analysis was used to examine the mediating effect of craving on the relationship between poor sleep and ketamine use. This study enrolled 414 current ketamine users with ketamine use disorder, 238 current ketamine users without ketamine use disorder, and 102 abstinent ketamine users with ketamine use disorder. Compared with healthy controls, all ketamine users had poor sleep quality. Poor sleep quality was associated with the initiation of and dependence on ketamine use. Craving can mediate the relationship between poor sleep quality and ketamine use. Poor sleep quality remains a problem for those abstaining from ketamine use. Poor sleep quality in ketamine users is an important issue because it is directly and indirectly through craving associated with ketamine use.

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.

New psychoactive substances in Taiwan: challenges and strategies

PURPOSE OF REVIEW

Abuse of new psychoactive substances (NPS) has been a new global concern. So far, there has been no international consensus on legislative control of NPS. Scrutiny of Taiwan's illegal drug use history reveals that legislation and policy play an important role in tackling the drug issues.

RECENT FINDINGS

Since the early 2000s, use of club drugs (mostly NPS) has become popular in local rave parties and dance clubs in Taiwan. Some NPS, such as ketamine, synthetic cathinones, and para-methoxymethamphetamine, have posed a risk to public health and a challenge to drug policy.

SUMMARY

The illegal drug use history in Taiwan was firstly briefly reviewed, and the recent NPS use situation was depicted. Heroin and methamphetamine have been the most predominant drugs, but NPS such as ketamine and synthetic cathinones have become a new issue. The toxicological profiles of commonly abused NPS in Taiwan, although limited, were discussed. By comparison of the legislative mechanism for NPS control between Taiwan, South Korea, and Japan, it was found that timely and flexible legislative mechanism(s) is essential for early identification, surveillance, and comprehensive evaluation. In addition, researches on NPS epidemiology and toxicology are needed to firm up evidence-based strategies for effective prevention, treatment, and harm reduction measures.

A randomized, double-blind, active placebo-controlled study of efficacy, safety, and durability of repeated vs single subanesthetic ketamine for treatment-resistant depression

The strategy of repeated ketamine in open-label and saline-control studies of treatment-resistant depression suggested greater antidepressant response beyond a single ketamine. However, consensus guideline stated the lack of evidence to support frequent ketamine administration. We compared the efficacy and safety of single vs. six repeated ketamine using midazolam as active placebo. Subjects received either six ketamine or five midazolam followed by a single ketamine during 12 days followed by up to 6-month post-treatment period. The primary end point was the change from baseline in the Montgomery-Åsberg Depression Rating Scale (MADRS) score at 24 h after the last infusion. Fifty-four subjects completed all six infusions. For the primary outcome measure, there was no significant difference in change of MADRS scores between six ketamine group and single ketamine group at 24 h post-last infusion. Repeated ketamine showed greater antidepressant efficacy compared to midazolam after five infusions before receiving single ketamine infusion. Remission and response favored the six ketamine after infusion 4 and 5, respectively, compared to midazolam before receiving single ketamine infusion. For those who responded, the median time-to-relapse was nominally but not statistically different (2 and 6 weeks for the single and six ketamine group, respectively). Repeated infusions were relatively well-tolerated. Repeated ketamine showed greater antidepressant efficacy to midazolam after five infusions but fell short of significance when compared to add-on single ketamine to midazolam at the end of 2 weeks. Increasing knowledge on the mechanism of ketamine should drive future studies on the optimal balance of dosing ketamine for maximum antidepressant efficacy with minimum exposure.

Neurobehavioral, testicular and erectile impairments of chronic ketamine administration: Pathogenesis and ameliorating effect of N-acetyl cysteine

Ketamine, a dissociative anesthetic, recently has spread as a recreational drug. Its abuse lead to neurobehavioral disturbance in addition to toxic effects on other body organs. To evaluate the toxic effects of chronic administration of low ketamine doses on the memory, testicles, and erection, explore its pathophysiology through oxidative stress mechanism and examine the ameliorating effect of N-acetyl cysteine (NAC). A total of 40 male albino rats were assigned to control, vehicle, ketamine only I.P. (10 mg/kg), and ketamine (10 mg/kg) + NAC (150 mg/kg) groups. Assessment of memory affection and erectile function by Passive Avoidance, Novel Object Recognition, and copulatory tests were performed. Estimation of malondialdehyde (MDA), catalase (CAT), and total antioxidant capacity (TAC) in serum and prefrontal & hippocampal homogenate, and luteinizing hormone (LH), testosterone in serum were done. Prefrontal cortex, hippocampus, and testes were collected for histopathology. Chronic ketamine administration induced significant memory deficits (P < 0.05), reduced erectile function (P < 0.05), severe hypospermatogenesis, increased MDA, reduced CAT, TAC levels in serum, and tissue homogenate (P < 0.05) and reduction of LH, and testosterone (P < 0.05). Treatment with NAC resulted in significant improvement of memory function, improved erectile function, and decrease in oxidative injury in both serum and tissue homogenates. Testosterone and LH levels exhibited significant difference between treatment groups and controls (P < 0.05). NAC reduced the deleterious histopathological changes. These data suggest that long-term ketamine affects short and long memory, induces erectile and testicular dysfunction through oxidative stress. Co-administration with NAC ameliorates these toxic effects.

Ketamine in Major Depressive Disorder: Mechanisms and Future Perspectives

Major depressive disorder (MDD) is a serious psychiatric illness that causes functional impairment in many people. While monoaminergic antidepressants have been used to effectively treat MDD, these antidepressants have limitations in that they have delayed onset of action and many patients remain treatment-resistant. Therefore, there is a need to develop antidepressants with a novel target, and researchers have directed their attention to the glutamatergic system. Ketamine, although developed as an anesthetic, has been found to produce an antidepressant effect at sub-anesthetic doses via N-Methyl-D-aspartic acid (NMDA) receptor blockade as well as NMDA receptor- independent pathways. A single infusion of ketamine produced rapid improvement in clinical symptoms to a considerable level and led to the resolution of serious depressive symptoms, including imminent suicidal ideation, in patients with MDD. A series of recent randomized controlled trials have provided a high level of evidence for the therapeutic efficacy of ketamine treatment in MDD and presented new insights on the dose, usage, and route of administration of ketamine as an antidepressant. With this knowledge, it is expected that ketamine treatment protocols for MDD will be established as a treatment option available in clinical practice. However, long-term safety must be taken into consideration as ketamine has abuse potential and it is associated with psychological side effects such as dissociative or psychotomimetic effects.

Development of an addiction index and delineation 15-year trends of illicit drugs from the Taiwan national drug enhancement database

Illicit drug use contributes to substantial morbidity and mortality. Drug scheduling, a legal measure in drug enforcement, is often structured as a hierarchy based on addiction tendency, abuse trends, and harm, but may lack data-driven evidence when classifying substances. Our study aims to measure addiction tendency and use trends based on real-world data. We used the open access database of National Police Agency, Ministry of the Interior in Taiwan and analyzed all daily criminal cases of illicit drugs from 2013 to 2017 and monthly illicit drug enforcement data from the same database from 2002 to 2017. We hypothesized that repeat and frequent use despite legal consequence may be a reflection of addictive behavior, and empirical mode decomposition was applied in analysis to calculate addiction tendency indices and intrinsic 15-year use trends. Our analysis showed heroin has the highest addiction index, followed by methamphetamine. 3,4-Methyl enedioxy methamphetamine, marijuana, and ketamine had lower addictive propensities. This result is consistent with most drug scheduling hierarchies. 15-year use trends of substances were consistent with previous epidemiological studies.

Management of Treatment-Resistant Depression in Real-World Clinical Practice Settings Across Asia

PURPOSE

Consensus is lacking on the management of treatment-resistant depression (TRD), resulting in significant variations on how TRD patients are being managed in real-world practice. A survey explored how clinicians managed TRD across Asia, followed by an expert panel that interpreted the survey results and provided recommendations on how TRD could be managed in real-world clinical settings.

METHODS

Between March and July 2018, 246 clinicians from Hong Kong, Japan, Mainland China, South Korea, and Taiwan completed a survey related to their treatment approaches for TRD.

RESULTS

The survey showed physicians using more polytherapy (71%) compared to maintaining patients on monotherapy (29%). The most commonly (23%) administered polytherapy involved antidepressant augmentation with antipsychotics that 19% of physicians also indicated as their most important approach for managing TRD. The highest number of physicians (34%) ranked switching to another class of antidepressants as their most important approach, while 16% and 9% chose antidepressant combinations and electroconvulsive therapy (ECT), respectively.

CONCLUSION

Taking into account the survey results, the expert panel made general recommendations on the management of TRD. TRD partial-responders to antidepressants should be considered for augmentation with second-generation antipsychotics. For non-responders, switching to another class of antidepressants ought to be considered. TRD patients achieving remission with acute treatment should consider continuing their antidepressants for at least another 6 months to prevent relapse. ECT is a treatment consideration for patients with severe depression or persistent symptoms despite multiple adequate trials of antidepressants. Physicians should also consider the response, tolerability and adherence to the current and previous antidepressants, the severity of symptoms, comorbidities, concomitant medications, preferences, and cost when choosing a TRD treatment approach for each individual patient.

Mis-anaesthetized society: expectancies and recreational use of ketamine in Taiwan

Background

The popularity of ketamine for recreational use has been increasing in Asia, including Taiwan. Still, little known about the pattern of ketamine expectancies and whether such patterns are related to ketamine use. This study aimed to examine whether the positive and negative ketamine expectancies are differentially associated with ketamine-using behavior, and whether such relationship may differ by early-onset use of tobacco or alcohol.

Methods

Participants were recruited using respondent-driven sampling (RDS) among regular tobacco and alcohol users, aged 18 to 50, residing in Taipei from 2007 to 2010. Totally 1115 participants (with an age distribution skewed to the right, median = 26; interquartile range: 22–32) had information on substance use and completed a 12-item ketamine expectancies questionnaire (with 6 positive and 6 negative statements). Using two axes of High and Low expectancies, the four combinations of binary positive and binary negative ketamine expectancies were created. Each participant’s drug-using experience was categorized into illicit drug naïve, exclusive ketamine use, polydrug ketamine use, or other illicit drug use. Using the weights in the network output by RDS Analysis Tool, multivariable logistic regression analysis was then conducted.

Results

The weighted prevalence was 2.4% for exclusive ketamine use, 9.0% for polydrug ketamine use, and 9.1% for the other illicit drug use. Ketamine users (11.4%) had greater positive expectancies and lower negative expectancies, particularly the combination of High Positive with Low Negative, as compared to the illicit drug-naïve or other illicit drug users. After adjustment for early-onset tobacco (or alcohol) use and sociodemographic characteristics, High Positive, Low Negative, and their combination of High Positive-Low Negative expectancies remained strongly associated with ketamine uses, without evidence of moderation from early-onset use of tobacco or alcohol.

Conclusions

Positive and negative ketamine expectancies were associated in opposite directions with ketamine use, independent of early-onset use of tobacco or alcohol. Our results indicate ketamine expectancies as possible targets for future intervention and prevention of ketamine use, with a less confrontational feedback on decreasing an individual’s positive expectancies is essential in preventing young people from the initiation of ketamine use.

Local Ketamine Improves Postoperative Analgesia After Third Molar Surgery

PURPOSE

Evidence exists to support the peripheral analgesic effect of local administration of ketamine (LAK) after third molar surgery. The aim of the present systematic review and meta-analysis was to determine the efficacy of LAK in the control of pain, swelling, and trismus after third molar surgery.

MATERIALS AND METHODS

The study design was a systematic review with a meta-analysis of the effect of LAK after third molar surgery. A search in electronic databases was performed from September 2017 to February 2019. Only prospective clinical trials and randomized controlled trials that had evaluated LAK after third molar surgery were included. The meta-analysis was based on the random effects model. The outcome measures evaluated were postoperative acute pain, swelling, and trismus. The estimated overall effect size was a standardized mean difference (SMD).

RESULTS

A total of 110 study subjects (men and women aged 18 to 50 years) were evaluated for the analgesic effect. The SMD showed a significant analgesic effect (postoperative pain control) favoring LAK (SMD, -1.7403; 95% confidence interval [CI], -2.45 to -1.04). Evaluation of the anti-inflammatory effect of LAK included 105 study subjects and resulted in significantly less swelling in the first postoperative day (SMD, -0.6169; 95% CI, -1.1654 to -0.0683). However, LAK did not reduce the incidence of trismus after third molar surgery (SMD, -0.7241; 95% CI, -2.2765 to 0.8284).

CONCLUSIONS

The use of LAK can reduce the incidence and severity of postoperative pain after third molar surgery and had an anti-inflammatory effect, although only in the first postoperative day. However, LAK had no effect on trismus reduction after third molar surgery.

The effects of sub-anesthetic ketamine plus ethanol on behaviors and apoptosis in the prefrontal cortex and hippocampus of adolescent rats

Ketamine has become increasingly popular in adolescent drug abusers worldwide. Meanwhile, alcohol is usually used by ketamine users. However, little work has been conducted to examine the chronic combined effects of ketamine and ethanol on adolescent brain. Here we probed into the effects of chronic administration of ketamine at recreational doses alone or combined with ethanol on behaviors and neuron damage in an adolescent rat model. 28-day old rats were treated with either 20 or 30 mg/kg ketamine plus or not plus 10% ethanol daily for 21 days. Depressive like behaviors, anxiety like behavior and memory impairment were tested using open field test, forced swimming test, elevated plus maze and Morris water maze. Apoptosis in prefrontal cortex (PFC) and hippocampus (HIP) were determined by the TdT-mediated dUTP Nick-End Labeling (TUNEL) and protein and mRNA levels of caspase-3, Bax and Bcl-2. Results show that co-application of ketamine and ethanol significantly increased immobility time in the forced swimming test, up-regulated TUNEL positive cells and both protein and mRNA expressions of caspase-3 and Bax, compared with the control group and ketamine and ethanol use alone groups in the PFC, but not in the HIP. Our study suggests that chronic co-administration of ketamine and ethanol results in depressive-like behavior and the caspase-dependent apoptosis in the PFC of adolescent rats' brains.

Lamotrigine attenuates the motivation to self-administer ketamine and prevents cue- and prime-induced reinstatement of ketamine-seeking behavior in rats

BACKGROUND

Lamotrigine is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. A case report has demonstrated that a ketamine addict experienced a significant reduction in craving and ketamine use after taking lamotrigine. The present study determined whether lamotrigine can reduce the motivation for ketamine and prevent the relapse to ketamine seeking behavior in rats.

METHODS

Male Sprague-Dawley rats were trained to respond for intravenous ketamine (0.5 mg/kg/infusion) self-administration or food pellets. The effects of lamotrigine on the motivation for ketamine or food were assessed using breakpoint test under a progressive ratio (PR) paradigm. Furthermore, the effects of lamotrigine on reinstatement of ketamine-seeking and food-seeking behaviors were examined after extinction.

RESULTS

Lamotrigine significantly decreased the breakpoint for ketamine and prevented cue- and ketamine priming-induced reinstatement of ketamine seeking behavior. However, lamotrigine did not affect the breakpoint for food reinforcement, cue-induced reinstatement of food-seeking behavior, or spontaneous locomotor activity.

CONCLUSIONS

Our data reveal that lamotrigine is capable of attenuating the reinforcing efficacy of ketamine and reducing ketamine craving and relapse risk, which lays the foundation for conducting clinical trials in patients with ketamine use disorder.

Difference in long-term relapse rates between youths with ketamine use and those with stimulants use

BACKGROUND

Understanding the relapse risk among different illicit drugs is vital for developing an adequate relapse prevention policy. Therefore, the current study aims to explore the potential difference in long-term relapse rates between youths who use ketamine and those who use stimulants (3,4-Methylenedioxymethamphetamine [MDMA] or methamphetamine).

METHODS

The study's participants included 92 youths with ketamine use (ketamine group, mean age: 16.0 years) and 43 youths with MDMA/methamphetamine use (stimulants group, mean age: 16.1 years) that had undergone a family-oriented treatment program in a medical center in Taiwan. All participants were followed up for a maximum of 7 years in order to observe their long-term outcomes with regard to substance use relapse.

RESULTS

During the follow-up period, compared to the 34.8% relapse rate in ketamine users, their counterparts who used MDMA or methamphetamine had a significantly higher relapse rate (60.5%, Adjusted HR = 1.86, 95%CI: 1.06-3.28, p = 0.032). Of the youths in the ketamine group that relapsed, 65.6% continued to use ketamine in their relapse event, while 34.4% switched to MDMA or methamphetamine. Among the relapsing youths in the stimulants group, 84.6% continued to use MDMA or methamphetamine in their relapse event, while 15.4% switched to ketamine (p = 0.042).

CONCLUSIONS

Compared to adolescents who use ketamine, those using MDMA or methamphetamine had higher relapse rates and were more likely to use the same type of drug upon relapsing. These results can serve as a crucial reference for developing relapse prevention policies of illicit drugs for the youth population.

Addictive potential of novel treatments for refractory depression and anxiety

Treatment-resistant mood disorders and anxiety disorders require intensive treatment, but treatment options should balance benefits and adverse effects or other potential detrimental effects on patients, including the risk of developing prescription medication addiction. Some of the newer treatment modalities for mood and anxiety disorders may have similar properties to benzodiazepines. The goal of this review was to identify the potential for developing dependence on the novel treatment approaches to treatment-resistant depression and refractory anxiety disorders. PubMed, MEDLINE, PsycINFO, Ovid, Cochrane Library, and Google Scholar were searched. Ketamine is effective in improving symptoms of major depressive disorder, but with no sustained benefits. Long-term use of oral or intranasal ketamine formulations may be associated with the risk of developing dependence. Augmentation of stimulant medication is usually effective for residual symptoms of depression, but the effects are usually short lasting and there is a potential for abuse. Synthetic cannabinoids and medicinal cannabis are increasingly being prescribed for a number of medical conditions, including anxiety disorders, without enough evidence about their efficacy and with the risk of patients developing dependence. In summary, benzodiazepines, ketamine, stimulant medications, and cannabinoids have some common characteristics, including short-lasting benefits and the risk of developing prescription medication addiction with longer use. All of these treatments may raise ethical dilemmas about the appropriateness of prescribing these medications in the long run for patients with depression and anxiety disorders.

Alcohol aggravates ketamine-induced behavioral, morphological and neurochemical alterations in adolescent rats: The involvement of CREB-related pathways

Currently, an increasing proportion of adolescent ketamine users simultaneously consume alcohol. However, the potential behavioural and neurological alterations induced by such a drug combination and the underlying mechanisms have not been systematically examined. Therefore, in the present study, the behavioural and morphological changes and the underlying mechanisms were studied in adolescent rats after repeated alcohol and/or ketamine treatment. This study provided the first evidence that co-administration of alcohol (2 and 4 g/kg, i.g.) in adolescent rats significantly potentiated the neurotoxic properties of repeated ketamine (30 mg/kg, i.p.) treatments over 14 days, manifesting as increased locomotor activity, stereotypic behaviour, ataxia and morphological changes. This potentiation was associated with the enhancement by alcohol of ketamine-induced glutamate (Glu) and dopamine (DA) release in the cortex and hippocampus. Further mechanistic study demonstrated that alcohol potentiated ketamine-induced neurotoxicity through down-regulation of Akt (a serine/threonine kinase or protein kinase, PKB), protein kinase A (PKA), calmodulin-dependent kinase IV (CaMK-IV)-mediated cyclic AMP-responsive element binding protein (CREB) pathways and induction of neuronal apoptosis in the cortex and hippocampus of the adolescent rats. As this study provides strong evidence that repeated alcohol and ketamine co-exposure may cause serious neurotoxicity, attention needs to be drawn to the potential risk of this consumption behaviour, especially for adolescents.

Ketamine for the treatment of major depressive disorder and bipolar depression: A review of the literature

Introduction

Over the past decade, ketamine has been studied for major depressive disorder and bipolar depression. Ketamine is believed to exert its antidepressant properties through N-methyl-D-aspartate receptor antagonism.

Methods

Study authors completed a literature review of seven randomized controlled trials of ketamine usage in major depressive disorder and bipolar depression.

Results

Ketamine demonstrated a statistically significant improvement over placebo or midazolam in major depressive disorder. Ketamine also exhibited a statistically significant improvement over placebo in bipolar depression.

Discussion

Ketamine has shown promise in quickly reducing symptoms in patients with treatment resistant depression and bipolar depression. Using ketamine may be helpful for patients that have exhausted other therapeutic options.