Ketamine dependence

The Pharmacological Management of Ketamine Use Disorder: A Systematic Review

OBJECTIVES

There has been limited evidence synthesis examining treatment of ketamine use disorder. We aimed to conduct a systematic review to assess the efficacy and tolerability of pharmacological interventions in the management of ketamine use disorder.

METHODS

We searched MEDLINE, EMBASE, PsychINFO, and CENTRAL (Cochrane Central Register of Controlled Trials) from database inception to November 14, 2023, for studies of any design that reported on any pharmacological intervention in the management of ketamine use disorder. We extracted any reported measure of efficacy or tolerability and assessed outcome quality using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework. We planned to combine outcomes using random-effects meta-analysis, where this was not possible results were reported narratively.

RESULTS

Twelve studies met the inclusion criteria reporting on 368 participants. These comprised 1 controlled trial, 2 retrospective case series, and 9 case reports. Two studies reported on ketamine intoxication, 6 on withdrawal, and 4 on craving/relapse prevention. All studies reported only descriptive outcomes, and all evidence was of very low quality. Benzodiazepine regimens and haloperidol were reported to have potential utility in intoxication and withdrawal, whereas naltrexone, lamotrigine, and a combination of paliperidone palmitate and bupropion were reported to have potential utility in craving/relapse prevention.

CONCLUSIONS

There is a paucity of research into pharmacological management of ketamine use disorder. The limited very low-quality evidence suggests benzodiazepine regimens may be most salient for future exploration in management of ketamine intoxication and withdrawal, whereas case reports suggest naltrexone, lamotrigine, and paliperidone palmitate plus bupropion may potentially merit further investigation with regard to craving/relapse prevention.

The cyclical revival of psychedelics in psychiatric treatment

There is an increasing demand for effective treatments for depression, particularly for individuals grappling with treatment-resistant depression. Over recent years, a surge of interest has focused on exploring the safety and efficacy of psilocybin as a potential treatment for depression. However, preliminary findings from phase 2 studies have been inconclusive, prompting critical examination of issues such as maintaining blinding and the role of adjunctive psychotherapy. The maintenance of double-blinding and the role of adjunctive psychotherapy introduce biases that complicate the attainment of conclusive results in clinical research. Examining historical data reveals a recurrent pattern linked to the use of psychoactive substances, which starts with an excess of optimism and ends with general addictive behaviors and a heightened risk of serious public health problems. Considering these findings, a cautious and measured approach is imperative, given that the efficacy and safety of psilocybin treatment have yet to be unequivocally established. The potential for excessive optimism among researchers is a notable concern, as unwarranted enthusiasm may inadvertently facilitate the widespread adoption of this treatment without sufficient empirical support. In navigating the complexities of depression treatment, it is necessary to strike a balance between innovation and prudence to ensure evidence-based advancement of therapeutic approaches.

Ketamine-induced uropathy: A narrative systemic review of surgical outcomes of reconstructive surgery

Aims

Refractory ketamine-induced uropathy (KU) (RKU) has devastating effects on the lower urinary tract leading to ureteral obstruction and even renal failure. The only effective treatment for RKU is major surgical reconstruction or urinary diversion. Nevertheless, there is a paucity of awareness about this destructive condition; the aim of this study is to conduct a narrative systemic review of all surgical outcomes of RKU.

Methods

This is an English language literature review of surgical outcomes in KU patients who underwent reconstructive lower urinary tract surgery or urinary diversion through 5 August 2022. Two independent researchers assessed the relevance of each paper and disputes were settled by a third party. In-vitro, animal studies, letters to the editor and papers that did not evaluate surgical outcomes were excluded.

Results

Of the 50 763 identified articles, 622 were relevant based on title, 150 based on abstract, but only 23 papers were relevant by content. In all, 875 patients were documented as having KU, of whom 193 (22%) underwent reconstructive surgery. The data were disconcerting, as the apparent rapid progression from the beginning of KU to end-stage bladder was only a 1-year difference of ketamine abuse between those patients who required surgery (4.4 years) and those that did not (3.4 years).

Conclusions

The data suggest that the time interval from the beginning of ketamine-induced uropathy to the end-stage bladder may be measured in months, confounding decision making. There is a dearth of literature about KU, and more research is needed to better understand this pathology.

Narrative Review: Low-Dose Ketamine for Pain Management

Pain is the leading cause of medical consultations and occurs in 50-70% of emergency department visits. To date, several drugs have been used to manage pain. The clinical use of ketamine began in the 1960s and it immediately emerged as a manageable and safe drug for sedation and anesthesia. The analgesic properties of this drug were first reported shortly after its use; however, its psychomimetic effects have limited its use in emergency departments. Owing to the misuse and abuse of opioids in some countries worldwide, ketamine has become a versatile tool for sedation and analgesia. In this narrative review, ketamine's role as an analgesic is discussed, with both known and new applications in various contexts (acute, chronic, and neuropathic pain), along with its strengths and weaknesses, especially in terms of psychomimetic, cardiovascular, and hepatic effects. Moreover, new scientific evidence has been reviewed on the use of additional drugs with ketamine, such as magnesium infusion for improving analgesia and clonidine for treating psychomimetic symptoms. Finally, this narrative review was refined by the experience of the Pain Group of the Italian Society of Emergency Medicine (SIMEU) in treating acute and chronic pain with acute manifestations in Italian Emergency Departments.

Arylcyclohexylamine Derivatives: Pharmacokinetic, Pharmacodynamic, Clinical and Forensic Aspects

Since the 2000s, an increasing number of new psychoactive substances (NPS) have appeared on the drug market. Arylcyclohexylamine (ACH) compounds such as ketamine, phencyclidine and eticyclidine derivatives are of particular concern, given their rapidly increasing use and the absence of detailed toxicity data. First used mainly for their pharmacological properties in anesthesia, their recreational use is increasing. ACH derivatives have an antagonistic activity against the N-methyl-D-aspartate receptor, which leads to dissociative effects (dissociation of body and mind). Synthetic ketamine derivatives produced in Asia are now arriving in Europe, where most are not listed as narcotics and are, thus, legal. These structural derivatives have pharmacokinetic and pharmacodynamic properties that are sometimes very different from ketamine. Here, we describe the pharmacology, epidemiology, chemistry and metabolism of ACH derivatives, and we review the case reports on intoxication.

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.

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.

Acute and Persistent Withdrawal Syndromes Following Discontinuation of Psychotropic Medications

Studies on psychotropic medications decrease, discontinuation, or switch have uncovered withdrawal syndromes. The present overview aimed at analyzing the literature to illustrate withdrawal after decrease, discontinuation, or switch of psychotropic medications based on the drug class (i.e., benzodiazepines, nonbenzodiazepine benzodiazepine receptor agonists, antidepressants, ketamine, antipsychotics, lithium, mood stabilizers) according to the diagnostic criteria of Chouinard and Chouinard [Psychother Psychosom. 2015;84(2):63-71], which encompass new withdrawal symptoms, rebound symptoms, and persistent post-withdrawal disorders. All these drugs may induce withdrawal syndromes and rebound upon discontinuation, even with slow tapering. However, only selective serotonin reuptake inhibitors, serotonin noradrenaline reuptake inhibitors, and antipsychotics were consistently also associated with persistent post-withdrawal disorders and potential high severity of symptoms, including alterations of clinical course, whereas the distress associated with benzodiazepines discontinuation appears to be short-lived. As a result, the common belief that benzodiazepines should be substituted by medications that cause less dependence such as antidepressants and antipsychotics runs counter the available literature. Ketamine, and probably its derivatives, may be classified as at high risk for dependence and addiction. Because of the lag phase that has taken place between the introduction of a drug into the market and the description of withdrawal symptoms, caution is needed with the use of newer antidepressants and antipsychotics. Within medication classes, alprazolam, lorazepam, triazolam, paroxetine, venlafaxine, fluphenazine, perphenazine, clozapine, and quetiapine are more likely to induce withdrawal. The likelihood of withdrawal manifestations that may be severe and persistent should thus be taken into account in clinical practice and also in children and adolescents.

Methoxphenidine (MXP) induced abnormalities: Addictive and schizophrenia-related behaviours based on an imbalance of neurochemicals in the brain

BACKGROUND AND PURPOSE

Methoxphenidine is a dissociative-based novel psychoactive designer drug. Although fatal accidents from methoxphenidine abuse have been reported, recreational use of the drug continues. We aim to provide scientific supportfor legal regulation of recreational abuse of methoxphenidine by demonstrating its the pharmacological action.

EXPERIMENTAL APPROACH

Addictive potential of methoxphenidine was examined using intravenous self-administration test with rats and conditioned place preference test with mice. Further, a series of behavioural tests (open field test, elevated plus maze test, novel object recognition test, social interaction test and tail suspension test) performed to assess whether methoxphenidine caused schizophrenia-related symptoms in mice. Additionally, neurotransmitter enzyme-linked immunosorbent assay and western blot were used to confirm methoxphenidine-induced neurochemical changes in specific brain regions related to abnormal behaviours.

KEY RESULTS

Methoxphenidine caused addictive behaviours via reinforcing and rewarding effects. Consistently, methoxphenidine induced over-activation of dopamine pathways in the nuclear accumbens, indicating activation of the brain reward circuit. Also, methoxphenidine caused all categories of schizophrenia-related symptoms, including positive symptoms (hyperactivity, impulsivity), negative symptoms (anxiety, social withdrawal, depression) and cognitive impairment. Consistently, methoxphenidine led to the disruption of the hippocampal-prefrontal cortex pathway that is considered to be pathological involved in schizophrenia.

CONCLUSIONS AND IMPLICATIONS

We demonastrate that methoxphenidine causes addictive and schizophrenia-like behaviours and induces neurochemical changes in brain regions associated with these behaviours. We propose that methoxphenidine could be used in developing useful animal disease models and that it also requires legal restrictions on its recreational use.

[History of Ketamine: An ancient molecule that is still popular today]

The history of ketamine begins in 1962, when Calvin Stevens of the pharmaceutical laboratory Parke-Davis synthesizes it from phencyclidine, a molecule with psychodysleptic, hallucinogenic and dissociative properties. Following the first administration of ketamine to humans in 1964 in Jackson prison (Michigan, USA), its dissociative effects associated with short anaesthesia were reported, and a patent for its human use was filed in 1966. In the 1990s, the discovery of opioid-induced hyperalgesia sparked interest in ketamine as an analgesic. In recent years, the human use of ketamine, and in particular its esketamine enantiomer, has shifted towards the treatment of depression. The first cases of ketamine abuse were reported in 1992 in France, leading to special surveillance by the health authorities, and its inclusion in the list of narcotic drugs in 1997. Today, ketamine has become an attractive substance for recreational use, gradually emerging from alternative techno circles to spread to more commercial party scenes. These elements represent a public health concern, associated with the risk of developing new chemically synthesized analogues, the harmful effects of which are still little known.

nNOS-mediated protein-protein interactions: promising targets for treating neurological and neuropsychiatric disorders

Neurological and neuropsychiatric disorders are one of the leading causes of disability worldwide and affect the health of billions of people. Nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS) in the brain. Inhibiting nNOS benefits a variety of neurological and neuropsychiatric disorders, including stroke, depression and anxiety disorders, post-traumatic stress disorder, Parkinson's disease, Alzheimer's disease, chronic pain, and drug addiction. Due to critical roles of nNOS in learning and memory and synaptic plasticity, direct inhibition of nNOS may cause severe side effects. Importantly, interactions of several proteins, including post-synaptic density 95 (PSD-95), carboxy-terminal PDZ ligand of nNOS (CAPON) and serotonin transporter (SERT), with the PSD/Disc-large/ZO-1 homologous (PDZ) domain of nNOS have been demonstrated to influence the subcellular distribution and activity of the enzyme in the brain. Therefore, it will be a preferable means to interfere with nNOS-mediated protein-protein interactions (PPIs), which do not lead to undesirable effects. Herein, we summarize the current literatures on nNOS-mediated PPIs involved in neurological and neuropsychiatric disorders, and the discovery of drugs targeting the PPIs, which is expected to provide potential targets for developing novel drugs and new strategy for the treatment of neurological and neuropsychiatric disorders.

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.

Overlap in the neural circuitry and molecular mechanisms underlying ketamine abuse and its use as an antidepressant

Ketamine, a dissociative anesthetic and psychedelic compound, has revolutionized the field of psychopharmacology by showing robust, and rapid-acting antidepressant activity in patients suffering from major depressive disorder (MDD), suicidal tendencies, and treatment-resistant depression (TRD). Ketamine's efficacy, however, is transient, and patients must return to the clinic for repeated treatment as they experience relapse. This is cause for concern because ketamine is known for its abuse liability, and repeated exposure to drugs of abuse often leads to drug abuse/dependence. Though the mechanism(s) underlying its antidepressant activity is an area of current intense research, both clinical and preclinical evidence shows that ketamine's effects are mediated, at least in part, by molecular adaptations resulting in long-lasting synaptic changes in mesolimbic brain regions known to regulate natural and drug reward. This review outlines our limited knowledge of ketamine's neurobiological and biochemical underpinnings mediating its antidepressant effects and correlates them to its abuse potential. Depression and addiction share overlapping neural circuitry and molecular mechanisms, and though speculative, repeated use of ketamine for the treatment of depression could lead to the development of substance use disorder/addiction, and thus should be tempered with caution. There is much that remains to be known about the long-term effects of ketamine, and our lack of understanding of neurobiological mechanisms underlying its antidepressant effects is a clear limiting factor that needs to be addressed systematically before using repeated ketamine in the treatment of depressed patients.

Efficacy and safety of intranasal esketamine for the treatment of major depressive disorder

Introduction: In March 2019, intranasal esketamine was approved by the Food and Drug Administration (FDA) for the treatment of treatment-resistant depression (TRD) in adults. This review presents the results of clinical trials underlying the FDA approval of intranasal esketamine.Areas covered: Esketamine's efficacy and safety in TRD were assessed in 5 phase III studies: three 4-week, placebo-controlled studies, and two long-term trials. One short-term trial showed statistically significant antidepressant effects of esketamine vs placebo, while a long-term withdrawal study showed that esketamine is significantly beneficial in terms of extending time to relapse, compared to placebo. Two other short-term trials did not meet the prespecified statistical tests for showing efficacy, although improvement in depressive symptoms from baseline to the end of week 4 favors esketamine over placebo.Expert opinion: Intranasal esketamine is a new treatment option for people with TRD. The main benefit of esketamine is rapid onset of antidepressant activity, but the effects of prolonged treatment are still preliminary. The main concerns relate to the safety aspects of prolonged esketamine therapy, when considering its abuse potential. While data for esketamine use over a long period of time is lacking, its use should be carefully monitored.

Dependence, withdrawal and rebound of CNS drugs: an update and regulatory considerations for new drugs development

The purpose of this article is to describe dependence and withdrawal phenomena related to CNS drugs discontinuation and to clarify issues related to the evaluation of clinical drug withdrawal and rebound as they relate to safety in new drug development. The article presents current understanding and definitions of drug dependence and withdrawal which are also relevant and important features of addiction, though not the same. Addiction, called substance use disorder in DSM-5, affects an individual’s brain and behaviour, represents uncontrollable drug abuse and inability to stop taking a drug regardless of the harm it causes. Characteristic withdrawal syndromes following abrupt discontinuation of CNS-active drugs from numerous drug classes are described. These include drugs both scheduled and non-scheduled in the Controlled Substances Act, which categorizes drugs in five schedules based on their relative abuse potentials and dependence liabilities and for regulatory purposes. Schedules 1 and 2 contain drugs identified as those with the highest abuse potential and strictest regulations. Less recognized aspects of drug withdrawal, such as rebound and protracted withdrawal syndromes for several drug classes are also addressed. Part I presents relevant definitions and describes clinical withdrawal and dependence phenomena. Part II reviews known withdrawal syndromes for the different drug classes, Part III describes rebound and Part IV describes protracted withdrawal syndromes. To our knowledge, this is the first compilation of withdrawal syndromes for CNS drugs. Part V provides details of evaluation of dependence and withdrawal in the clinical trials for CNS drugs, which includes general design recommendations, and several tools, such as withdrawal questionnaires and multiple scales that are helpful in the systematic evaluation of withdrawal. The limitations of different aspects of this method of dependence and withdrawal evaluation are also discussed.

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.

Ketamine and Ketamine Metabolite Pharmacology: Insights into Therapeutic Mechanisms

Ketamine, a racemic mixture consisting of (S)- and (R)-ketamine, has been in clinical use since 1970. Although best characterized for its dissociative anesthetic properties, ketamine also exerts analgesic, anti-inflammatory, and antidepressant actions. We provide a comprehensive review of these therapeutic uses, emphasizing drug dose, route of administration, and the time course of these effects. Dissociative, psychotomimetic, cognitive, and peripheral side effects associated with short-term or prolonged exposure, as well as recreational ketamine use, are also discussed. We further describe ketamine's pharmacokinetics, including its rapid and extensive metabolism to norketamine, dehydronorketamine, hydroxyketamine, and hydroxynorketamine (HNK) metabolites. Whereas the anesthetic and analgesic properties of ketamine are generally attributed to direct ketamine-induced inhibition of N-methyl-D-aspartate receptors, other putative lower-affinity pharmacological targets of ketamine include, but are not limited to, γ-amynobutyric acid (GABA), dopamine, serotonin, sigma, opioid, and cholinergic receptors, as well as voltage-gated sodium and hyperpolarization-activated cyclic nucleotide-gated channels. We examine the evidence supporting the relevance of these targets of ketamine and its metabolites to the clinical effects of the drug. Ketamine metabolites may have broader clinical relevance than was previously considered, given that HNK metabolites have antidepressant efficacy in preclinical studies. Overall, pharmacological target deconvolution of ketamine and its metabolites will provide insight critical to the development of new pharmacotherapies that possess the desirable clinical effects of ketamine, but limit undesirable side effects.

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.

Evaluating the abuse potential of psychedelic drugs as part of the safety pharmacology assessment for medical use in humans

Psychedelics comprise drugs come from various pharmacological classes including 5-HT_2A agonists, indirect 5-HT agonists, e.g., MDMA, NMDA antagonists and κ-opioid receptor agonists. There is resurgence in developing psychedelics to treat psychiatric disorders with high unmet clinical need. Many, but not all, psychedelics are schedule 1 controlled drugs (CDs), i.e., no approved medical use. For existing psychedelics in development, regulatory approval will require a move from schedule 1 to a CD schedule for drugs with medical use, i.e., schedules 2-5. Although abuse of the psychedelics is well documented, a systematic preclinical and clinical evaluation of the risks they pose in a medical-use setting does not exist. We describe the non-clinical tests required for a regulatory evaluation of abuse/dependence risks, i.e., drug-discrimination, intravenous self-administration and physical dependence liability. A synopsis of the existing data for the various types of psychedelics is provided and we describe our findings with psychedelic drugs in these models. FDA recently issued its guidance on abuse/dependence evaluation of drug-candidates (CDER/FDA, 2017). We critically review the guidance, discuss the impact this document will have on non-clinical abuse/dependence testing, and offer advice on how non-clinical abuse/dependence experiments can be designed to meet not only the expectations of FDA, but also other regulatory agencies. Finally, we offer views on how these non-clinical tests can be refined to provide more meaningful information to aid the assessment of the risks posed by CNS drug-candidates for abuse and physical dependence. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.

ZLc002, a putative small-molecule inhibitor of nNOS interaction with NOS1AP, suppresses inflammatory nociception and chemotherapy-induced neuropathic pain and synergizes with paclitaxel to reduce tumor cell viability

Elevated N-methyl-D-aspartate receptor activity contributes to central sensitization. Our laboratories and others recently reported that disrupting protein-protein interactions downstream of N-methyl-D-aspartate receptors suppresses pain. Specifically, disrupting binding between the enzyme neuronal nitric oxide synthase and either its upstream (postsynaptic density 95 kDa, PSD95) or downstream (e.g. nitric oxide synthase 1 adaptor protein, NOS1AP) protein partners suppressed inflammatory and/or neuropathic pain. However, the lack of a small-molecule neuronal nitric oxide synthase-NOS1AP inhibitor has hindered efforts to validate the therapeutic utility of disrupting the neuronal nitric oxide synthase-NOS1AP interface as an analgesic strategy. We, therefore, evaluated the ability of a putative small-molecule neuronal nitric oxide synthase-NOS1AP inhibitor ZLc002 to disrupt binding between neuronal nitric oxide synthase and NOS1AP using ex vivo, in vitro, and purified recombinant systems and asked whether ZLc002 would suppress inflammatory and neuropathic pain in vivo. In vitro, ZLc002 reduced co-immunoprecipitation of full-length NOS1AP and neuronal nitric oxide synthase in cultured neurons and in HEK293T cells co-expressing full-length neuronal nitric oxide synthase and NOS1AP. However, using a cell-free biochemical binding assay, ZLc002 failed to disrupt the in vitro binding between His-neuronal nitric oxide synthase1-299 and glutathione S-transferase-NOS1AP400-506, protein sequences containing the required binding domains for this protein-protein interaction, suggesting an indirect mode of action in intact cells. ZLc002 (4-10 mg/kg i.p.) suppressed formalin-evoked inflammatory pain in rats and reduced Fos protein-like immunoreactivity in the lumbar spinal dorsal horn. ZLc002 also suppressed mechanical and cold allodynia in a mouse model of paclitaxel-induced neuropathic pain. Anti-allodynic efficacy was sustained for at least four days of once daily repeated dosing. ZLc002 also synergized with paclitaxel when administered in combination to reduce breast (4T1) or ovarian (HeyA8) tumor cell line viability but did not alter tumor cell viability without paclitaxel. Our results verify that ZLc002 disrupts neuronal nitric oxide synthase-NOS1AP interaction in intact cells and demonstrate, for the first time, that systemic administration of a putative small-molecule inhibitor of neuronal nitric oxide synthase-NOS1AP suppresses inflammatory and neuropathic pain.

1,2-Diarylethylamine- and Ketamine-Based New Psychoactive Substances

While phencyclidine (PCP) and ketamine remain the most well-studied and widely known dissociative drugs, a number of other agents have appeared since the late 1950s and early 1960s, when the pharmacological potential of this class was first realized. For example, hundreds of compounds have been pursued as part of legitimate research efforts to explore these agents. Some of these found their way out of the research labs and onto illicit markets of the 1960s and following decades as PCP analogs. Other "illicit analogs" apparently never appeared in the scientific literature prior to their existence on clandestine markets, thus originating as novel innovations in the minds of clandestine chemists and their colleagues. Like so much else in this world, new technologies changed this dynamic. In the 1990s individuals separated by vast geographical distances could now communicate nearly instantaneously with ease through the Internet. Some individuals used this newly found opportunity to discuss the chemistry and psychoactive effects of dissociative drugs as well as to collaborate on the design and development of novel dissociative compounds. Similar to modern pharmaceutical companies and academic researchers, these seekers tinkered with the structure of their leads pursuing goals such as improved duration of action, analgesic effects, and reduced toxicity. Whether all these goals were achieved for any individual compound remains to be seen, but their creations have been let out of the bag and are now materialized as defined compositions of matter. Moreover, these creations now exist not only in and of themselves but live on further as permutations into various novel analogs and derivatives. In some cases these compounds have made their way to academic labs where potential clinical applications have been identified. These compounds reached wider distribution when other individuals picked up on these discussions and began to market them as "research chemicals" or "legal highs". The result is a continuously evolving game that is being played between legislatures, law enforcement, and research chemical market players. Two structurally distinct classes that have appeared as dissociative-based new psychoactive substances (NPS) are the 1,2-diarylethylamines and β-keto-arylcyclohexylamines. Examples of the former include diphenidine and various analogs such as fluorolintane and N-ethyl-lanicemine, and examples of the latter are analogs of ketamine such as methoxetamine, deschloroketamine, and 2-fluoro-2-deschloroketamine. The subject of this chapter is the introduction to some of the dissociative NPS from these classes and their known pharmacology that have emerged on the market in recent years.

Side-effects associated with ketamine use in depression: a systematic review

This is the first systematic review of the safety of ketamine in the treatment of depression after single and repeated doses. We searched MEDLINE, PubMed, PsycINFO, and Cochrane Databases and identified 288 articles, 60 of which met the inclusion criteria. After acute dosing, psychiatric, psychotomimetic, cardiovascular, neurological, and other side-effects were more frequently reported after ketamine treatment than after placebo in patients with depresssion. Our findings suggest a selective reporting bias with limited assessment of long-term use and safety and after repeated dosing, despite these being reported in other patient groups exposed to ketamine (eg, those with chronic pain) and in recreational users. We recommend large-scale clinical trials that include multiple doses of ketamine and long-term follow up to assess the safety of long-term regular use.

Small molecule inhibitors of PSD95-nNOS protein-protein interactions suppress formalin-evoked Fos protein expression and nociceptive behavior in rats

Excessive activation of NMDA receptor (NMDAR) signaling within the spinal dorsal horn contributes to central sensitization and the induction and maintenance of pathological pain states. However, direct antagonism of NMDARs produces undesirable side effects which limit their clinical use. NMDAR activation produces central sensitization, in part, by initiating a signaling cascade that activates the enzyme neuronal nitric oxide synthase (nNOS) and generates the signaling molecule nitric oxide. NMDAR-mediated activation of nNOS requires a scaffolding protein, postsynaptic density protein 95kDa (PSD95), which tethers nNOS to NMDARs. Thus, disrupting the protein-protein interaction between PSD95 and nNOS may inhibit pro-nociceptive signaling mechanisms downstream of NMDARs and suppress central sensitization while sparing unwanted side effects associated with NMDAR antagonists. We examined the impact of small molecule PSD95-nNOS protein-protein interaction inhibitors (ZL006, IC87201) on both nociceptive behavior and formalin-evoked Fos protein expression within the lumbar spinal cord of rats. Comparisons were made with ZL007, an inactive analog of ZL006, and the NMDAR antagonist MK-801. IC87201 and ZL006, but not ZL007, suppressed phase 2 of formalin-evoked pain behavior and decreased the number of formalin-induced Fos-like immunoreactive cells in spinal dorsal horn regions associated with nociceptive processing. MK-801 suppressed Fos protein expression in both dorsal and ventral horns. MK-801 produced motor ataxia in the rotarod test whereas IC87201 and ZL006 failed to do so. ZL006 but not ZL007 suppressed paclitaxel-induced mechanical and cold allodynia in a model of chemotherapy-induced neuropathic pain. Co-immunoprecipitation experiments revealed the presence of the PSD95-nNOS complex in lumbar spinal cord of paclitaxel-treated rats, although ZL006 did not reliably disrupt the complex in all subjects. The present findings validate use of putative small molecule PSD95-nNOS protein-protein interaction inhibitors as novel analgesics and demonstrate, for the first time, that these inhibitors suppress inflammation-evoked neuronal activation at the level of the spinal dorsal horn.

Group II mGlu receptor antagonist LY341495 enhances the antidepressant-like effects of ketamine in the forced swim test in rats

RATIONALE

Numerous preclinical and clinical studies have reported the rapid and sustained antidepressant effects of the NMDA receptor antagonist ketamine. Because ketamine induces several undesirable and dangerous effects, a variety of strategies have been suggested to avoid such effects.

OBJECTIVES

Here, we propose to enhance the sub-effective doses of ketamine by co-administration with the group II metabotropic glutamate (mGlu) receptor antagonist LY341495. This compound potentially acts as an antidepressant via a mechanism similar to that of ketamine.

METHODS

To investigate the rapid and sustained antidepressant-like effects of these drugs, we administered ketamine and LY341495 individually or in combination, 40 min and 24 h before the forced swim test (FST).

RESULTS

We found that sub-effective doses of ketamine and LY341495, given jointly, induce significant antidepressant-like effects, at both 40 min and 24 h after administration. The results obtained using Western blot technique indicate that mammalian target of rapamycin (mTOR) pathway activation may be involved in the mechanism of this action. The effects of drugs, used at identical ranges of times and doses, on spontaneous locomotor activity in rats were excluded. Furthermore, the results obtained from the rota-rod test and the ketamine-induced hyperlocomotion test suggest a lack of potentially adverse effects from the combined administration of ketamine and LY341495 at doses previously used in the FST.

CONCLUSION

Altogether, these data suggest that the joint administration of ketamine and LY341495 might be a noteworthy alternative to the use of solely ketamine in the therapy of depression.

Nonconventional interventions for chronic post-traumatic stress disorder: Ketamine, repetitive trans-cranial magnetic stimulation (rTMS), and alternative approaches

It is alarming that only 59% of those who have post-traumatic stress disorder (PTSD) respond to selective serotonin reuptake inhibitors. Many existing treatments, both pharmacological and nonpharmacological, do not directly target trauma memories that lay at the core of the PTSD pathogenesis. Notable exceptions are medications like ketamine and propranolol and trauma-focused psychotherapies like eye-movement desensitization and reprocessing therapy (developed by Shapiro) and Trauma Interventions using Mindfulness Based Extinction and Reconsolidation (TIMBER) for trauma memories (developed by Pradhan). Although the antidepressant effects of ketamine are no longer news, ketamine's effects on treatment refractory PTSD (TR-PTSD) is a recent concept. As TR-PTSD has a marked public health burden and significant limitations in terms of treatment interventions, a thorough assessment of current strategies is required. Research to bring clarity to the underlying pathophysiology and neurobiology of TR-PTSD delineating the chemical, structural, and circuitry abnormalities will take time. In the interim, in the absence of a 1-size-fits-all therapeutic approach, pragmatically parallel lines of research can be pursued using the pharmacological and nonpharmacological treatments that have a strong theoretical rationale for efficacy. This article aims to review the current literature on interventions for PTSD, most notably ketamine, trans-cranial magnetic stimulation treatment, yoga and mindfulness interventions, and TIMBER. We present an outline for their future use, alone as well as in combination, with a hope of providing additional insights as well as advocating for developing more effective therapeutic intervention for this treatment-resistant and debilitating condition.

Ketamine dependence in an anesthesiologist: an occupational hazard?

Substance abuse among medical professionals is a cause for concern. Certain psychotropic substances such as ketamine are at easy dispense to anesthesiologists increasing the likelihood of misuse and dependence and raise several issues including safety of patients. We discuss a case demonstrating ketamine dependence in an anesthesiologist from India. The reported psychotropic effects of ketamine ranged from dissociation and depersonalization to psychotic experiences. There was also development of significant tolerance to ketamine without prominent physical withdrawal symptoms and cyclical use of very high doses was observed. Issues related to management of health professionals are also discussed.

Severity of club drug dependence and perceived need for treatment among a sample of adult club drug users in Shanghai, China

PURPOSE

Examine the severity of club drug dependence and perceived need for treatment, and further identify their determinants among a sample of club drug users in Shanghai, China.

METHODS

Two hundred and seventy-six club drug users were recruited using respondent-driven sampling (RDS). Severity of dependence on club drugs was measured using the Severity of Dependence Scale (SDS).

RESULTS

69.9% reported dependence on club drugs (i.e., SDS ≥ 4) and 36.6% reported severe dependence (i.e., SDS ≥ 6). One-eighth (12.7%) perceived need for drug treatment. Severe dependence on club drugs was more likely among those who reported recent use of ecstasy and those who had more depressive symptoms, but less likely among those reporting recent use of methamphetamine. Perceived need for treatment was more likely among those who lived with a spouse or boy/girlfriend, but less likely among those had prior drug treatment experience and more severe club drug dependence.

CONCLUSIONS

Our findings suggest that educational activities should be implemented to raise public awareness about the powerful addictive properties of club drugs, along with efforts to reduce stigma towards drug abuse and psychiatric disorders. Programs to motivate drug users to seek treatment and encourage treatment linkage are urgently needed.

Psychiatric side effects of medications prescribed in internal medicine

Several pharmacological treatments used in internal medicine can induce psychiatric side effects (PSEs) that mimic diagnoses seen in psychiatry. PSEs may occur upon withdrawal or intoxication, and also at usual therapeutic doses. Drugs that may lead to depressive, anxious, or psychotic syndromes include corticosteroids, isotretinoin, levo-dopar mefloquine, interferon-a, and anabolic steroids, as well as some over-the-counter medications. PSEs are often difficult to diagnose and can be very harmful to patients. PSEs are discussed in this review, as well as diagnostic clues to facilitate their identification.

Ketamine use: a review

AIMS

Ketamine remains an important medicine in both specialist anaesthesia and aspects of pain management. At the same time, its use as a recreational drug has spread in many parts of the world during the past few years. There are now increasing concerns about the harmful physical and psychological consequences of repeated misuse of this drug. The aim of this review was to survey and integrate the research literature on physical, psychological and social harms of both acute and chronic ketamine use.

METHOD

The literature on ketamine was systematically searched and findings were classified into the matrix of Nutt et al.'s (2007) rational scale for assessing the harms of psychoactive substances.

RESULTS

A major physical harm is ketamine induced ulcerative cystitis which, although its aetiology is unclear, seems particularly associated with chronic, frequent use of the drug. Frequent, daily use is also associated with neurocognitive impairment and, most robustly, deficits in working and episodic memory. Recent studies suggest certain neurological abnormalities which may underpin these cognitive effects. Many frequent users are concerned about addiction and report trying but failing to stop using ketamine.

CONCLUSIONS

The implications of these findings are drawn out for treatment of ketamine-induced ulcerative cystitis in which interventions from urologists and from addiction specialists should be coordinated. Neurocognitive impairment in frequent users can impact negatively upon achievement in education and at work, and also compound addiction problems. Prevention and harm minimization campaigns are needed to alert young people to these harmful and potentially chronic effects of ketamine.

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

Ketamine, a derivative of phencyclidine that was developed in the 1960s, is an anesthetic and analgesic with hallucinogenic effects. In this paper, the pharmacological and toxicological effects of ketamine are briefly reviewed. Ketamine possesses a wide safety margin but such a therapeutic benefit is somewhat offset by its emergence phenomenon (mind-body dissociation and delirium) and hallucinogenic effects. The increasing abuse of ketamine, initially predominantly in recreational scenes to experience a “k-hole” and other hallucinatory effects but more recently also as a drug abused during the workday or at home, has further pushed governments to confine its usage in many countries. Recently, urinary tract dysfunction has been associated with long-term ketamine use. In some long-term ketamine users, such damage can be irreversible and could result in renal failure and dialysis. Although ketamine has not yet been scheduled in the United Nations Conventions, previous studies using different assessment parameters to score the overall harms of drugs indicated that ketamine may cause more harm than some of the United Nations scheduled drugs. Some countries in Southeast and East Asia have reported an escalating situation of ketamine abuse. Dependence, lower urinary tract dysfunction, and sexual impulse or violence were the most notable among the ketamine-associated symptoms in these countries. These results implied that the danger of ketamine may have been underestimated previously. Therefore, the severity levels of the ketamine-associated problems should be scrutinized more carefully and objectively. To prevent ketamine from being improperly used and evolving into an epidemic, a thorough survey on the prevalence and characteristics of illicit ketamine use is imperative so that suitable policy and measures can be taken. On the other hand, recent findings that ketamine could be useful for treating major depressive disorder has given this old drug a new impetus. If ketamine is indeed a remedy for treating depression, more research on the risks and benefits of its clinical use will be indispensable.

[Anesthesia in drug addiction]

The growing social problem of drug abuse has increased the likelihood that anesthesiologists will find acute or chronic drug users among patients requiring anesthesia for elective or emergency surgery. We must therefore be aware of the effects drugs have on the organism and their possible pharmacokinetic and pharmacodynamic interactions with anesthetic agents in order to prevent complications during surgery and postoperative recovery. Such knowledge is required for the management of abstinence syndrome or overdose, which pose the greatest potential dangers for the hospitalized drug addict.

Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse

Pharmacologic and toxic effects of xenobiotics, such as drugs of abuse, depend on the genotype and phenotype of an individual, and conversely on the isoenzymes involved in their metabolism and transport. The current knowledge of such isoenzymes of frequently abused therapeutics such as opioids (oxycodone, hydrocodone, methadone, fentanyl, buprenorphine, tramadol, heroin, morphine and codeine), anesthetics (γ-hydroxybutyric acid, propofol, ketamine and phencyclidine) and cognitive enhancers (methylphenidate and modafinil), and some important plant-derived hallucinogens (lysergide, salvinorin A, psilocybin and psilocin), as well as of nicotine in humans are summarized in this article. The isoenzymes (e.g., cytochrome P450, glucuronyltransferases, esterases and reductases) involved in the metabolism of drugs and some pharmacokinetic data are discussed. The relevance of such data is discussed for predicting possible interactions with other xenobiotics, understanding pharmacokinetic behavior and pharmacogenomic variations, assessing toxic risks, developing suitable toxicological analysis procedures, and finally for interpretating drug testing results.

Out-of-body experience and auditory and visual hallucinations in a patient with cardiogenic syncope: Crucial role of cardiac event recorder in establishing the diagnosis

Out-of-body experience (OBE) and visual and auditory hallucinations can occur in a variety of medical conditions. We describe a 48-year-old male patient who experienced several paroxysmal events with different combinations of the aforementioned symptoms that could finally be attributed to cardiogenic syncope after subcutaneous implantation of an event recorder and that ceased after implantation of a cardiac pacemaker. Hallucinations and OBE are well-known phenomena in syncope. The special purpose of this report is to highlight the crucial role of implantation of the event recorder in establishing the diagnosis and the additional support of the diagnosis by the cessation after implanting the cardiac pacemaker.

Attentional bias to incentive stimuli in frequent ketamine users

BACKGROUND

The attention-grabbing properties of drugs to drug-using individuals have been well documented and recent research has begun to suggest that such attentional bias may be related to the severity of drug dependency. Dependence on ketamine has been reported anecdotally but no systematic study has investigated this phenomenon. We aimed to explore attentional biases to incentive stimuli in different populations of ketamine users.

METHOD

Using a dot-probe paradigm, attentional bias to both drug-related and money-related stimuli was investigated in 150 participants: 30 frequent ketamine users, 30 infrequent ketamine users, 30 ex-ketamine users, 30 poly-drug users and 30 non-drug-using controls. Two stimulus presentation times were used (200 and 2000 ms) to investigate whether attentional bias was as a result of an automatic or a more conscious attentional shift. Participants also rated the degree to which stimuli used in the dot-probe paradigm were pleasurable.

RESULTS

Frequent ketamine users demonstrated an attentional bias to both types of incentive stimuli only at the short stimulus presentation interval and this was significantly correlated with degree of ketamine use. No attentional biases were observed in any of the other groups. All groups rated money stimuli as more pleasurable than neutral stimuli.

CONCLUSIONS

These data support incentive models of drug use and demonstrate the ability of the attentional bias paradigm to discriminate recreational drug users from those with more dependent patterns of use. Ketamine is a potentially dependence-forming drug.

Drug abuse and dependency during pregnancy: anaesthetic issues

Drug abuse is a significant social problem that can lead to serious obstetric complications, some of which may be confused with pregnancy-related disease states. Substance abuse poses a number of challenges with respect to the management of pain and the conduct of anaesthesia in the peripartum period. This review was based on information from a literature search of epidemiological, research and review papers on substance abuse during pregnancy, obtained for the purpose of preparing a background paper for the Ministerial Council on Drug Strategy, Commonwealth Government of Australia. Given that almost 80% of substance-abusing parturients require anaesthetic services in the perinatal period, early antenatal referral for anaesthetic review is recommended. To optimise the care of these vulnerable patients, obstetricians, general practitioners and midwives should attempt to identify substance-abusing parturients and refer them to an anaesthetist. A careful anaesthetic evaluation with non-judgemental questioning is essential, with management tailored to individual patient needs and the urgency of obstetric intervention for vaginal delivery or caesarean section. Opioid-dependent women, in particular, benefit from antenatal pain management planning. Patients recovering from drug addiction should also have a well-documented analgesic strategy. A multidisciplinary approach will involve obstetricians, anaesthetists and staff of the Drug and Alcohol Service. In acute admissions of women by whom antenatal care was not accessed, a high index of suspicion for illicit drug use should arise. Because illicit substance use is so prevalent, if untoward reactions occur during an otherwise uneventful anaesthetic, the possibility of drug abuse should be considered.

Brief review: Perioperative management of the patient with chronic non-cancer pain

PURPOSE

Both opioid and non-opioid medications are being utilized increasingly in the treatment of chronic non-cancer pain, and the number of surgical patients receiving large regular doses of opioids is ever-expanding. The perioperative pain control of these patients is often challenging, and is broadening the role of the anesthesiologist as 'perioperative physician'. These patients need to be identified before surgery to plan optimal pain control postoperatively. The purpose of this review is to provide an update on the important considerations in managing the chronic non-cancer pain patient receiving high dose opioids and other adjunctive medications/analgesics.

SOURCE

English language articles published between June 1980 and May 2006 were identified by a computerized Medline search using keywords (1/2)chronic pain(1/2), (1/2)opioid dependent(1/2) and (1/2)perioperative(1/2). This same search strategy was repeated and updated using both Medline and Embase. All relevant publications were retrieved and their bibliographies were scanned for additional sources.

PRINCIPAL FINDINGS

Although an increasingly common problem for the acute pain service, there is very little published on this topic. Key points include the concept of opioid equivalency, tolerance, the role of adjunctive medications, and the need for good communication between the surgical team, the acute pain service and the patient who is often anxious about the upcoming procedure due to previous unpleasant experiences with poor pain control in hospital.

CONCLUSION

Clinical care of the opioid-dependent patient in the perioperative period can be a daunting task. Education to all staff involved in this area needs to be enhanced to improve outcome and patient satisfaction.

The role of ketamine in pain management

Ketamine is a dissociative anaesthetic; its mechanism of action is primarily an antagonism of the N-methyl-D-aspartate (NMDA) receptor. The role of ketamine, in particular in lower sub-anaesthetic doses, has recently gained increasing interest in pain management. It has been studied in a considerable number of trials and analysed in meta-analyses and systematic reviews. Based on these data, the primary role of ketamine in such low doses is as an 'anti-hyperalgesic', 'anti-allodynic' or 'tolerance-protective' agent. It therefore has a role in the treatment of opioid resistant or 'pathological' pain (central sensitisation with hyperalgesia or allodynia, opioid induced hyperalgesia, neuropathic pain) rather than as an 'analgesic' in its own right. Low dose ketamine also has 'preventive analgesia' properties. Furthermore, in higher doses it provides effective and safe sedation and analgesia for painful procedures. The place of ketamine in the treatment of chronic pain and the effects of long-term medicinal use remain unclear.

Ketamine : from medicine to misuse

This review describes the medical, research and recreational uses of ketamine, an anaesthetic derivative of phencyclidine that has dissociative, analgesic and psychedelic properties. Ketamine has a complex mechanism of action that is further complicated by stereoselectivity; however, antagonism of glutamate NDMA receptors is thought to underlie its analgesic, dissociative and neuroprotective effects. While ketamine use in medical and veterinary settings is well documented and has a good safety record, the increase in its unregulated use outside of such controlled environments is a cause for concern. The impact on higher centres in the brain, particularly altered perception of auditory, visual and painful stimuli, results in a general lack of responsive awareness that puts the recreational user at (often unrecognised) risk of personal harm. The perceptual and mood changes observed in those who have consumed ketamine are highly sensitive to age, dose, route of administration, previous experience and setting. At low doses, stimulant effects predominate and the effect of environmental conditions are significant; with higher doses, psychedelic effects predominate and the effect of the environment diminishes. The potential of ketamine as a novel clinical and research tool is matched by its abuse potential outside medical settings.

Club Drugs and HIV Infection: A Review

Club drug use is common among populations with human immunodeficiency virus (HIV) and populations at high risk for HIV infection. Club drugs have a myriad of acute and chronic medical consequences. Club drug-related visits to the emergency department and admissions for treatment of substance use have increased dramatically over the past 15 years. Most epidemiological data support the role of club drugs in increasing sexual risk behavior, with some studies demonstrating an independent association between use of certain club drugs and HIV infection. The direct influence of club drugs on progression of HIV disease remains to be determined; however, club drugs may interact with certain retroviral medications and have been associated with decreased adherence to medication. Clinicians should ask all patients about patterns of club drug use, counsel patients about the risks associated with club drug use, and refer patients to appropriate behavioral treatment programs for substance use when clinically indicated.

Behavioral effects of ketamine and toxic interactions with psychostimulants

Background

The anesthetic drug ketamine (KT) has been reported to be an abused drug and fatal cases have been observed in polydrug users. In the present study, considering the possibility of KT-enhanced toxic effects of other drugs, and KT-induced promotion of an overdose without making the subject aware of the danger due to the attenuation of several painful subjective symptoms, the intraperitoneal (i.p.) KT-induced alterations in behaviors and toxic interactions with popular co-abused drugs, the psychostimulants cocaine (COC) and methamphetamine (MA), were examined in ICR mice.

Results

A single dose of KT caused hyperlocomotion in a low (30 mg/kg, i.p.) dose group, and hypolocomotion followed by hyperlocomotion in a high (100 mg/kg, i.p.) dose group. However, no behavioral alterations derived from enhanced stress-related depression or anxiety were observed in the forced swimming or the elevated plus-maze test. A single non-fatal dose of COC (30 mg/kg, i.p.) or MA (4 mg/kg, i.p.) caused hyperlocomotion, stress-related depression in swimming behaviors in the forced swimming test, and anxiety-related behavioral changes (preference for closed arms) in the elevated plus-maze test. For the COC (30 mg/kg) or MA (4 mg/kg) groups of mice simultaneously co-treated with KT, the psychostimulant-induced hyperlocomotion was suppressed by the high dose KT, and the psychostimulant-induced behavioral alterations in the above tests were reversed by both low and high doses of KT. For the toxic dose COC (70 mg/kg, i.p.)- or MA (15 mg/kg, i.p.)-only group, mortality and severe seizures were observed in some animals. In the toxic dose psychostimulant-KT groups, KT attenuated the severity of seizures dose-dependently. Nevertheless, the mortality rate was significantly increased by co-treatment with the high dose KT.

Conclusion

Our results demonstrated that, in spite of the absence of stress-related depressive and anxiety-related behavioral alterations following a single dose of KT treatment, and in spite of the KT-induced anticonvulsant effects and attenuation of stress- and anxiety-related behaviors caused by COC or MA, the lethal effects of these psychostimulants were increased by KT.

„Out-of-body experience“ als mögliches Anfallssymptom bei einem Patienten mit rechtsparietaler Läsion

Out-of-body experiences are reported in a variety of diseases and physiologic conditions. We report a 44-year-old patient with epigastric auras, psychomotor and grand mal seizures, and paroxysmal experiences during which he believed to have left his body and seen himself from the outside. Electroencephalography showed a right temporal and right parietal seizure pattern on several occasions, and a lesion in the right parietal lobe was detected by cranial magnetic resonance imaging. Histological examination showed a pleomorphic xanthoastrocytoma. Following extirpation of the lesion, the patient has been seizure-free for 5 years.

Recognition and management of complications of new recreational drug use

Use of illicit drugs in clubs and large dance parties (so-called raves) is a burgeoning cultural trend. Such recreational drug use is associated with several medical complications, both acute and longlasting. Although few, if any, of the drugs currently used in recreational venues are truly new, their patterns and context of use have changed (a great deal in some instances). For some of these substances, this cultural repackaging of the drug experience has resulted in various medical disorders that have previously gone undocumented. This review aims to help treating physicians recognise and manage complications associated with the use of new drugs in clubs, including methylenedioxymethamfetamine, ephedrine, gamma-hydroxybutyrate; gamma-butyrolactone, 1,4-butanediol, flunitrazepam, ketamine, and nitrites. We also alert researchers to specific toxic effects of club-drugs on which more basic information is needed.

Absence of behavioral sensitization in healthy human subjects following repeated exposure to ketamine

RATIONALE

Sensitization to the effects of N-methyl-D-aspartate (NMDA) glutamate receptor antagonists is robust in animals. However, the applicability of this model to humans is unclear because it currently rests on highly confounded retrospective studies of individuals who experienced protracted psychoses following repeated binges with NMDA receptor antagonists.

OBJECTIVES

The purpose of the current study was to determine whether there was evidence of sensitization to the behavioral effects of ketamine in healthy human subjects with repeated exposure to this drug.

METHODS

Data were studied from 295 healthy human subjects who participated in one or more of 11 separate studies that involved ketamine administration over 14 years. Positive and negative symptoms (Brief Psychiatric Rating Scale: BPRS), perceptual alterations (Clinician-Administered Dissociative States Scale: CADSS), and "high" and "anxiety" states (Visual Analog Scale: VAS) that were measured in all studies were included as outcome measures.

RESULTS

After including the number of previous exposures, number of previous studies, and time since first exposure as variables, repeated exposure to ketamine did not result in increased behavioral responses, suggestive of behavioral sensitization.

CONCLUSIONS

The current data do not provide evidence that repeated exposure to ketamine, albeit limited, is associated with sensitization to the behavioral effects of ketamine.

[Depersonalization--current data]

OBJECTIVE

Depersonalization is a fascinating clinical phenomenon referring to a self-consciousness disorder, characterized by emotional detachment from one's own feelings, thoughts, or actions. This article intends to summarize the current literature in this area.

METHOD

Using the Medline data base, we reviewed literature addressing the clinical, etiology, nosology, physiopathology, and treatment of depersonalization.

CONCLUSIONS

Derealization means that perception of the world and of external reality are altered. These 2 phenomena are often associated. They are not specific to any psychiatric entity and are reported in many different psychiatric syndromes. Many factors, including use of different substances, are involved in their onset. The physiopathology is still little known. However, some conceptual models suggest partial amygdala inhibition combined with activation of other amygdaloid structures. A serotoninergic functioning impairment is indicated in different pharmacologic studies. Different psychotropic drugs, especially serotoninergic antidepressants, have been proposed for pharmacotherapy; however, there are no conclusive randomized studies, and the contribution of psychotherapy in treating these patients is still questioned.