gamma-Hydroxybutyrate/sodium oxybate: neurobiology, and impact on sleep and wakefulness

GABAergic synaptic plasticity during a developmentally regulated sleep-like state in C. elegans

Approximately one-fourth of the neurons in Caenorhabditis elegans adults are born during larval development, indicating tremendous plasticity in larval nervous system structure. Larval development shows cyclical expression of sleep-like quiescent behavior during lethargus periods, which occur at larval stage transitions. We studied plasticity at the neuromuscular junction during lethargus using the acetylcholinesterase inhibitor aldicarb. The rate of animal contraction when exposed to aldicarb is controlled by the balance between excitatory cholinergic and inhibitory GABAergic input on the muscle. During lethargus, there is an accelerated rate of contraction on aldicarb. Mutant analysis and optogenetic studies reveal that GABAergic synaptic transmission is reduced during lethargus. Worms in lethargus show partial resistance to GABA(A) receptor agonists, indicating that postsynaptic mechanisms contribute to lethargus-dependent plasticity. Using genetic manipulations that separate the quiescent state from the developmental stage, we show that the synaptic plasticity is dependent on developmental time and not on the behavioral state of the animal. We propose that the synaptic plasticity regulated by a developmental clock in C. elegans is analogous to synaptic plasticity regulated by the circadian clock in other species.

End of life care in adolescents and young adults with cancer: experience of the adolescent unit of the Institut Gustave Roussy

BACKGROUND

Cancer is the third leading cause of death in adolescents and young adults (AYA). Little is known, however, about how end-of-life unfolds for those who die of progressive disease. In order to better evaluate the specific needs of these patients, we performed this study providing baseline information about end-of-life care patterns for AYA in our department.

PATIENTS

A standardised form was used to collect data concerning all 45 patients treated for a malignancy in the Paediatric and Adolescent Oncology Department at the Gustave Roussy Institute, and who had died of progressive disease above 13 years of age, over a two-year period.

RESULTS

The main diagnoses were sarcomas and brain tumours. Previous cancer-directed treatment included a median of 3 different chemotherapy regimens, high-dose chemotherapy with haematopoietic stem cell support for 13% and radiotherapy for 40%. One in every four patients had been enrolled in a clinical trial at diagnosis. Median survival was 18 months after the diagnosis and 7 months after the first relapse/progression. During the last week of life, the median number of physical symptoms was 4, mostly pain and dyspnoea. Frequent psychological symptoms were sadness, anxiety, fear and guilt. End-of-life care included transfusions, artificial nutrition, corticosteroids, pain control, sedation but also palliative chemotherapy. The median time spent in hospital during the last month of life was 16 days. Most patients had died in hospital.

CONCLUSIONS

The terminally ill adolescent displays notable challenges to care providers and requires a holistic approach with the help of a multidisciplinary team.

Drug-induced sleep: theoretical and practical considerations

Faithful replication of normal sleep through medications--can it be achieved? Departure from normal sleep with the use of drugs--when is it desired? Answers to these questions depend on accurate understanding of sleep and on concrete criteria upon which to define it. Since these elements are evolving sciences, as yet incompletely known, one might take a nihilistic approach that we simply cannot judge whether we have successfully replicated sleep, since we do not fully grasp what sleep is or what it does. To address these potential obstacles, our article is written in two sections. The first addresses theoretical considerations for how medications might be seen in the larger framework of sleep. The purpose of this section is to inform readers about key issues in evaluating whether a drug has sufficient data to persuasively argue it is re-creating sleep. (We hope that researchers interested in conducting studies, or critical readers of the drug-study literature, might find this section particularly useful.) The second section of this article approaches exemplary, current concepts of pharmacologic manipulation of sleep, organized by disorders as articulated by the International Classification of Sleep Disorders (2005). This second section will combine practical knowledge of clinical sleep medicine, with emphasis on contemporary knowledge about molecular mechanisms that are felt to underlie some of these phenomena. We recognize that our collective knowledge about sleep will advance in the coming years. We hope that this article serves to facilitate that advance.

Sodium oxybate: a potential new pharmacological option for the treatment of fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a common disorder, characterized by diffuse pain and tenderness, stiffness, fatigue, affective disorders and significant sleep pathology. A new set of diagnostic criteria have been developed which should make it easier for a busy clinician to diagnose the condition. US Food and Drug Administration (FDA) approved medications for the treatment of FMS have, for the most part, been geared to modulate the pain pathways to give the patient some degree of relief. A different kind of pharmacological agent, sodium oxybate (SXB), is described that is currently approved for the treatment of excessive daytime sleepiness and cataplexy in patients with narcolepsy. SXB, an endogenous metabolite of the inhibitory neurotransmitter gamma-hydroxybutyrate, is thought to act independently as a neurotransmitter with a presumed ability to modulate numerous other central nervous system neurotransmitters. In addition SXB has been shown to robustly increase slow wave sleep and decrease sleep fragmentation. Several large clinical trials have demonstrated SXB's ability to statistically improve pain, fatigue and a wide array of quality of life measurements of patients with fibromyalgia. SXB is not FDA approved to treat fibromyalgia.

Sodium oxybate for the treatment of fibromyalgia

INTRODUCTION

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid that is synthesized within the CNS, mostly from its parent compound gamma amino butyric acid (GABA). GHB acts as a neuromodulator/neurotransmitter to affect neuronal activity of other neurotransmitters and so, stimulate the release of growth hormone. Its sodium salt (sodium oxybate: SXB) was approved by the Food and Drug Administration (FDA) for the treatment of narcolepsy. SXB has shown to improve disrupted sleep and increase NR3 (slow-wave restorative) sleep in patients with narcolepsy. It is rapidly absorbed and has a plasma half-life of 30 - 60 min, necessitating twice-nightly dosing. Most of the observed effects of SXB result from binding to GABA-B receptors.

AREAS COVERED

Several randomized, controlled trials demonstrated significantly improved fibromyalgia (FM) symptoms with SXB. As seen in narcolepsy trials, SXB improved sleep of FM patients, increased slow-wave sleep duration as well as delta power, and reduced frequent night-time awakenings. Furthermore, FM pain and fatigue was consistently reduced with nightly SXB over time. Commonly reported adverse events included headache, nausea, dizziness and somnolence. Despite its proven efficacy, SXB did not receive FDA approval for the management of FM in 2010, mostly because of concerns about abuse.

EXPERT OPINION

Insomnia, fatigue and pain are important clinical FM symptoms that showed moderate improvements with SXB in several large, well-designed clinical trials. Because of the limited efficacy of currently available FM drugs additional treatment options are needed. In particular, drugs like SXB - which belong to a different drug class than other Food and Drug Administration (FDA)-approved FM medications such as pregabalin, duloxetine and milnacipran - would provide a much-needed addition to presently available treatment options. However, the FDA has set the bar high for future SXB re-submissions, with requirements of superior efficacy and improved risk mitigation strategies. At this time, no future FDA submission of SXB for the fibromyalgia indication is planned.

Sodium oxybate in maintaining alcohol abstinence in alcoholic patients with and without psychiatric comorbidity

Sodium oxybate (SMO) is a GABA-ergic drug currently used for the treatment of alcohol-dependence in some European countries. In particular, clinical studies have shown a role of SMO in promoting alcohol abstinence, as well as in relieving withdrawal symptoms. The aim of this study was to describe alcohol abstinence and the onset of craving for and abuse of SMO in alcohol-dependent subjects with and without psychiatric co-morbidity. Forty-eight patients were enrolled and classified into two groups: group A (20 alcoholics without any psychiatric co-morbidity) and group B (28 alcoholics with a psychiatric co-morbidity). All patients were treated with oral SMO (50 mg/kg of body weight t.i.d.) for 12 weeks. Alcohol abstinence as well as alcohol drinking during the 12 weeks of treatment did not differ between the two groups at the end of treatment (p=0.9). In addition, a reduction of alcohol intake in both groups has been observed (p<0.0001). On the other hand, craving for SMO was significantly more frequent in group B than group A (p=0.001). Cases of SMO abuse were observed in almost 10% of group B patients. In conclusion, alcohol abstinence achieved through SMO administration does not differ in patients with and without psychiatric co-morbidity. However, alcoholics with co-morbid borderline disorders appear to be at high risk of developing craving for and abuse of the drug; therefore, SMO may not be indicated in these patients.

Sodium oxybate in the treatment of binge eating disorder: an open-label, prospective study

OBJECTIVE

To assess preliminarily the effectiveness of sodium oxybate in binge eating disorder.

METHOD

This was an open-label, prospective, 16-week, flexible dose study of sodium oxybate in binge eating disorder. The primary outcome was binge eating episode frequency.

RESULTS

Twelve individuals received sodium oxybate, 10 completed at least one postbaseline evaluation, and five completed the study. Mean dose at endpoint was 7.1 (2.0) g/day. Sodium oxybate was associated with significant reductions in frequency of binge days and binge episodes, as well as measures of clinical severity, eating pathology, obsessive-compulsive symptoms, food cravings, body mass index, and body weight. Nine participants had remission of binge eating and five lost ≥5% of their baseline weight; all five of the latter participants had remission of binge eating.

DISCUSSION

In this open-label trial, sodium oxybate was effective in binge eating disorder, but associated with high a discontinuation rate.

A 2-week, polysomnographic, safety study of sodium oxybate in obstructive sleep apnea syndrome

PURPOSE

Sodium oxybate (SXB) is approved for cataplexy and excessive daytime sleepiness in narcolepsy. Obstructive sleep apnea syndrome (OSAS) affects ∼9-50% of narcoleptics. Effects of 2-week SXB administration on apnea-hypopnea index (AHI), oxygen saturation (SaO(2)), and sleep architecture were investigated in OSAS patients.

METHODS

OSAS patients (n = 48) received 2-week SXB or placebo (PBO) treatment with polysomnography at baseline and day 14. The primary outcome measure was change from baseline in mean AHI. Secondary outcomes included changes from baseline in SaO(2), and sleep architecture.

RESULTS

Compared with PBO, SXB significantly increased reduction in mean AHI and obstructive apnea index with SXB (-0.8 ± 13.3 vs. -8.2 ± 10.0; p = 0.0327 and 3.54 ± 11.1 vs. -4.72 ± 7.7; p = 0.0054, respectively) and significantly increased change in slow wave sleep duration (5.2 ± 25.0 min vs. 29.4 ± 37.0 min; p = 0.0038). There were no differences between treatments in SaO2, central apneic events, or other measures. Adverse events, most commonly headache, were noted in nine of 27 (33%) and six of 23 (26%) patients receiving SXB and PBO, respectively.

CONCLUSIONS

Short-term use of 4.5 g/night SXB did not generate respiratory depressant effects in OSAS patients as measured by AHI, obstructive apnea events, central apneas, and SaO2. Extended use of SXB in higher therapeutic doses in OSAS has not been studied, and merits caution.

Using isotopic tools to dissect and quantitate parallel metabolic pathways

4-Hydroxyacids are ubiquitous in human physiology. They are derived from the drugs of abuse gamma-hydroxybutyrate (GHB), gamma-hydroxypentanoate(GHP), in addition to the omnipresent lipid peroxidation product 4-hydroxy-2-(E)-nonenal (4-HNE). Previously we reported that 4-hydroxyacids are catabolized through two parallel pathways. In this report we detail two isotopic tools that have allowed the dissection of this catabolic process and illustrate how these tools can be used to quantify the relative flux down each pathway. We found that 4-hydroxynonanoate (4-hydroxyacid derived from 4-HNE) is primarly catabolized through a pathway that phosphorylates the C-4 hydroxyl and isomerizes it to a C-3 hydroxy compound, which is catabolized through beta-oxidation.

Slow-wave sleep deficiency and enhancement: implications for insomnia and its management

In humans, slow-wave sleep (SWS) consists of stages 3 and 4 of non rapid eye movement (nonREM) sleep. The low-frequency, high-amplitude slow waves that dominate the electroencephalogram (EEG) during SWS can be quantified as slow-wave activity (SWA). SWS and SWA are regulated very accurately in response to variations in the duration and intensity of wakefulness and sleep. SWA declines more or less independently of circadian phase during the course of a sleep episode, indicating that it is primarily under homeostatic rather than circadian control. An age-related decline in SWS and SWA is well established. In some studies, apprehension, depression and insomnia have been associated with reductions in SWS and SWA. Experimental reductions of SWS through SWS deprivation (without altering total sleep time or REM duration) have been reported to lead to an increase in daytime sleep propensity and reductions in performance. SWS and SWA are therefore thought to contribute to the recovery processes that occur during sleep. Most currently prescribed hypnotics, such as the benzodiazepines and Z-drugs, suppress SWA. Some compounds have been shown to enhance SWS and SWA in healthy volunteers through GAT-1 inhibition, GABA-A modulation, GABA-B modulation, and 5HT2(A) antagonism. Pharmacological enhancement of SWS has also been observed in insomnia. The effects of SWS enhancement on other sleep parameters will be discussed.

Gamma-hydroxybutyrate does not maintain self-administration but induces conditioned place preference when injected in the ventral tegmental area

Gamma-hydroxybutyric acid (GHB) is an endogenous brain substance that has diverse neuropharmacological actions, including rewarding properties in different animal species and in humans. As other drugs of abuse, GHB affects the firing of ventral tegmental neurons (VTA) in anaesthetized animals and hyperpolarizes dopaminergic neurons in VTA slices. However, no direct behavioural data on the effects of GHB applied in the VTA or in the target regions of its dopaminergic neurons, e.g. the nucleus accumbens (NAc), are available. Here, we investigated the effects of various doses of intravenous GHB in maintaining self-administration (from 0.001 to 10 mg/kg per infusion), and its ability to induce conditioned place preference (CPP) in rats when given orally (175-350 mg/kg) or injected directly either in the VTA or NAc (from 10 to 300 microg/0.5 microl per side). Our results indicate that while only 0.01 mg/kg per infusion GHB maintained self-administration, although not on every test day, 350 mg/kg GHB given orally induced CPP. CPP was also observed when GHB was injected in the VTA (30-100 microg/0.5 microl per side) but not in the NAc. Together with recent in-vitro findings, these results suggest that the rewarding properties of GHB mainly occur via disinhibition of VTA dopaminergic neurons.

A single acute pharmacological dose of γ-hydroxybutyrate modifies multiple gene expression patterns in rat hippocampus and frontal cortex

γ-Hydroxybutyrate (GHB) is a natural brain neuromodulator that has its own enzymatic machinery for synthesis and degradation, release, and transport systems and several receptors that belong to the G protein-coupled receptor (GPCR) family. Targeting of this system with exogenous GHB is used in therapy to induce sleep and anesthesia and to reduce alcohol withdrawal syndrome. GHB is also popular as a recreational drug for its anxiolytic and mild euphoric effects. However, in both cases, GHB must be administered at high doses in order to maintain GHB concentrations in brain of ∼800-1,000 μM. These high concentrations are thought to be necessary for interactions with low-affinity sites on GABA(B) receptor, but the molecular targets and cellular mechanisms modulated by GHB remain poorly characterized. Therefore, to provide new insights into the elucidation of GHB mechanisms of action and open new tracks for future investigations, we explored changes of GHB-induced transcriptomes in rat hippocampus and prefrontal cortex by using DNA microarray studies. We demonstrate that a single acute anesthetic dose of 1 g/kg GHB alters a large number of genes, 121 in hippocampus and 53 in prefrontal cortex; 16 genes were modified simultaneously in both brain regions. In terms of molecular functions, the majority of modified genes coded for proteins or nucleotide binding sites. In terms of Gene Ontology (GO) functional categories, the largest groups were involved in metabolic processing for hippocampal genes and in biological regulation for prefrontal cortex genes. The majority of genes modified in both structures were implicated in cell communication processes. Western blot and immunohistochemical studies carried out on eight selected proteins confirmed the microarray findings.

New approaches for the treatment of sleep disorders

Epidemiological studies have established that sleep disorders are common and often untreated. Besides having a negative impact on overall health, these conditions can significantly disrupt normal daily functions. While a number of drugs are employed in the treatment of sleep disorders, safety, tolerability, and variable efficacy limit their utility. Clinical developments in the area have been facilitated especially by advances in neurobiology and neuropharmacology. In this regard, a wide array of neuroactive substances has been found to be responsible for regulating sleep and wakefulness. Advances in the understanding of neurotransmitter and hormone receptor mechanisms and classifications have led to new opportunities for developing novel therapeutics for treating sleep disorders. Provided in this report is an overview of some of the more prevalent sleep disorders, including narcolepsy, insomnia, obstructive sleep apnea syndrome, and restless legs syndrome, with a summary and critique of medications used to treat these conditions. For each disorder, information is provided on recent approaches taken to develop novel therapeutics based on laboratory findings relating to the underlying biological abnormalities associated with the condition, in addition to approaches that leverage existing therapeutics to develop new treatment options for patients. Significant advances in the future await a better understanding of the underlying pathophysiology of these conditions and of the neurobiological alterations associated with these disorders. It is hoped that some of the research directions described herein will stimulate additional research in this area and thereby help foster the discovery of novel agents for treating major sleep disorders.

Incidence of craving for and abuse of gamma-hydroxybutyric acid (GHB) in different populations of treated alcoholics: an open comparative study

Gamma-hydroxybutyric acid (GHB) is a drug currently used for the treatment of alcohol dependence. The aim of our study was to investigate the incidence of craving for and abuse of GHB in 47 patients enrolled and divided into four groups: group A (pure alcoholics), group B (alcoholics with a sustained full remission from cocaine dependence), group C (alcoholics with a sustained full remission from heroin dependence) and group D (alcoholics in a methadone maintenance treatment [MMT] programme). All patients were treated with an oral dose of GHB (50 mg/kg of body weight t.i.d.) for three months. Craving for GHB was statistically significant higher in group B than in group A (P < 0.001), C (P = 0.01) and D (P < 0.001), and in group C than in group D (P < 0.05). Abuse of GHB proved to be statistically significant higher in group B than in group A (P < 0.001) and D (P < 0.01), and in group C than in group A (P = 0.01) and D (P < 0.05). Thus, the administration of GHB in alcoholics with a sustained full remission from heroin or cocaine dependence is not recommended; however, this should not discourage physicians from using GHB for the treatment of pure alcoholics or alcohol dependents following a MMT.

Catabolism of 4-hydroxyacids and 4-hydroxynonenal via 4-hydroxy-4-phosphoacyl-CoAs

4-Hydroxyacids are products of ubiquitously occurring lipid peroxidation (C(9), C(6)) or drugs of abuse (C(4), C(5)). We investigated the catabolism of these compounds using a combination of metabolomics and mass isotopomer analysis. Livers were perfused with various concentrations of unlabeled and labeled saturated 4-hydroxyacids (C(4) to C(11)) or 4-hydroxynonenal. All the compounds tested form a new class of acyl-CoA esters, 4-hydroxy-4-phosphoacyl-CoAs, characterized by liquid chromatography-tandem mass spectrometry, accurate mass spectrometry, and (31)P-NMR. All 4-hydroxyacids with five or more carbons are metabolized by two new pathways. The first and major pathway, which involves 4-hydroxy-4-phosphoacyl-CoAs, leads in six steps to the isomerization of 4-hydroxyacyl-CoA to 3-hydroxyacyl-CoAs. The latter are intermediates of physiological beta-oxidation. The second and minor pathway involves a sequence of beta-oxidation, alpha-oxidation, and beta-oxidation steps. In mice deficient in succinic semialdehyde dehydrogenase, high plasma concentrations of 4-hydroxybutyrate result in high concentrations of 4-hydroxy-4-phospho-butyryl-CoA in brain and liver. The high concentration of 4-hydroxy-4-phospho-butyryl-CoA may be related to the cerebral dysfunction of subjects ingesting 4-hydroxybutyrate and to the mental retardation of patients with 4-hydroxybutyric aciduria. Our data illustrate the potential of the combination of metabolomics and mass isotopomer analysis for pathway discovery.

Illicit gamma-hydroxybutyrate (GHB) and pharmaceutical sodium oxybate (Xyrem): differences in characteristics and misuse

There are distinct differences in the accessibility, purity, dosing, and misuse associated with illicit gamma-hydroxybutyrate (GHB) compared to pharmaceutical sodium oxybate. Gamma-hydroxybutyrate sodium and sodium oxybate are the chemical and drug names, respectively, for the pharmaceutical product Xyrem (sodium oxybate) oral solution. However, the acronym GHB is also used to refer to illicit formulations that are used for non-medical purposes. This review highlights important differences between illicit GHB and sodium oxybate with regard to their relative abuse liability, which includes the likelihood and consequences of abuse. Data are summarized from the scientific literature; from national surveillance systems in the U.S., Europe, and Australia (for illicit GHB); and from clinical trials and post-marketing surveillance with sodium oxybate (Xyrem). In the U.S., the prevalence of illicit GHB use, abuse, intoxication, and overdose has declined from 2000, the year that GHB was scheduled, to the present and is lower than that of most other licit and illicit drugs. Abuse and misuse of the pharmaceutical product, sodium oxybate, has been rare over the 5 years since its introduction to the market, which is likely due in part to the risk management program associated with this product. Differences in the accessibility, purity, dosing, and misuse of illicit GHB and sodium oxybate suggest that risks associated with illicit GHB are greater than those associated with the pharmaceutical product sodium oxybate.

Narcolepsy and depression and the neurobiology of gammahydroxybutyrate

A voluminous literature describes the relationship between disturbed sleep and depression. The breakdown of sleep is one of the cardinal features of depression and often also heralds its onset. Frequent arousals, periods of wakefulness and a short sleep onset REM latency are typical polysomnographic features of depression. The short latency to REM sleep has been attributed to the combination of a monoaminergic deficiency and cholinergic supersensitivity and these irregularities have been proposed to form the biological basis of the disorder. A similar imbalance between monoaminergic and cholinergic neurotransmission has been found in narcolepsy, a condition in which frequent awakenings, periods of wakefulness and short sleep onset REM latencies are also characteristic findings during sleep. In many cases of narcolepsy, this imbalance appears to result from a deficiency of hypocretin but once established, whether in depression or narcolepsy, this disequilibrium sets the stage for the dissociation or premature appearance of REM sleep and for the dissociation of the motor inhibitory component of REM sleep or cataplexy. In the presence of this monoaminergic/cholinergic imbalance, gammahydroxybutyrate (GHB) may acutely further reduce the latency of REM sleep and induce cataplexy, in both patients with narcolepsy or depression. On the other hand, the repeated nocturnal application of GHB in patients with narcolepsy improves the continuity of sleep, prolongs the latency to REM sleep and prevents cataplexy. Evidence to date suggests that GHB may restore the normal balance between monoaminergic and cholinergic neurotransmission. As such, the repeated use of GHB at night and the stabilization of sleep over time makes GHB an effective treatment for narcolepsy and a potentially effective treatment for depression.

Sedative and hypothermic effects of gamma-hydroxybutyrate (GHB) in rats alone and in combination with other drugs: assessment using biotelemetry

The recreational drug gamma-hydroxybutyrate (GHB) has euphoric effects and can induce sedation and body temperature changes. GHB is frequently combined with other recreational drugs although these interactions are not well characterised. The present study used biotelemetry to provide a fine-grained analysis of the effects of GHB on body temperature and locomotor activity in freely moving rats, and investigated interactions between GHB and 3,4-methylenedioxymethamphetamine (MDMA), methamphetamine (METH) and various antagonist drugs. GHB (1000mg/kg) caused profound sedation for more than 2h and a complex triphasic effect on body temperature: an initial hypothermia (5-40min), followed by hyperthermia (40-140min), followed again by hypothermia (140-360min). A lower GHB dose (500mg/kg) also caused sedation but only a hypothermic effect that lasted up to 6h. The dopamine D(1) receptor antagonist SCH 23390 (1mg/kg), the opioid antagonist naltrexone (1mg/kg), the benzodiazepine antagonist flumazenil (10mg/kg), and the 5-HT(2A/2C) receptor antagonist ritanserin (1mg/kg) did not prevent the overall sedative or body temperature effects of GHB (1000mg/kg). However the GABA(B) antagonist SCH 50911 (50mg/kg) prevented the hyperthermia induced by GHB (1000mg/kg). Repeated daily administration of GHB (1000mg/kg) produced tolerance to the sedative and hyperthermic effects of the drug and cross-tolerance to the sedative effects of the GABA(B) receptor agonist baclofen (10mg/kg). A high ambient temperature of 28 degrees C prevented the hypothermia obtained with GHB (500mg/kg) at 20 degrees C, while GHB (500mg/kg) reduced the hyperthermia and hyperactivity produced by co-administered doses of MDMA (5mg/kg) or METH (1mg/kg) at 28 degrees C. These results further confirm a role for GABA(B) receptors in the hypothermic and sedative effects of GHB and show an interaction between GHB and MDMA, and GHB and METH, that may be relevant to the experience of recreational users who mix these drugs.

A Patient with Intractable Posthypoxic Myoclonus (Lance-Adams Syndrome) Treated with Sodium Oxybate

Posthypoxic myoclonus is a rare and devastating complication of near-fatal cardiopulmonary arrest. Despite treatment with available anti-myoclonic agents, some patients may recover cognitively but remain completely disabled by severe myoclonus. We report a 16-year-old patient with severe treatment-refractory posthypoxic myoclonus, which improved markedly with administration of the drug sodium oxybate.

Behavioral analyses of GHB: receptor mechanisms

GHB is used therapeutically and recreationally, although the precise mechanism of action responsible for its different behavioral effects is not entirely clear. The purpose of this review is to summarize how behavioral procedures, especially drug discrimination procedures, have been used to study the mechanism of action of GHB. More specifically, we will review several different drug discrimination procedures and discuss how they have been used to qualitatively and quantitatively study different components of the complex mechanism of action of GHB. A growing number of studies have provided evidence that the behavioral effects of GHB are mediated predominantly by GABAB receptors. However, there is also evidence that the mechanisms mediating the effects of GHB and the prototypical GABAB receptor agonist baclofen are not identical, and that other mechanisms such as GHB receptors and subtypes of GABAA and GABAB receptors might contribute to the effects of GHB. These findings are consistent with the different behavioral profile, abuse liability, and therapeutic indications of GHB and baclofen. A better understanding of the similarities and differences between GHB and baclofen, as well as the pharmacological mechanisms of action underlying the recreational and therapeutic effects of GHB, could lead to more effective medications with fewer adverse effects.

The distribution of gamma-hydroxybutyrate-induced Fos expression in rat brain: comparison with baclofen

gamma-Hydroxybutyrate (GHB) is a euphoric, prosocial and sleep inducing drug that binds with high affinity to its own GHB receptor site and also more weakly to GABA(B) receptors. GHB is efficacious in the treatment of narcolepsy and alcoholism, but heavy use can lead to dependence and withdrawal. Many effects of GHB (sedation, hypothermia, catalepsy) are mimicked by GABA(B) receptor agonists (e.g. baclofen). However other effects (euphoric and prosocial effects and a therapeutic effect in narcolepsy) are not. The present study used Fos immunohistochemistry to assess the neural activation produced in rat brain by medium to high doses of GHB (250, 500 and 1000 mg/kg) and a high dose of baclofen (10 mg/kg) that produced similar sedation to 500 mg/kg GHB. Results showed many common regions of activation with these two drugs including the supraoptic, paraventricular, median preoptic and ventral premammillary nuclei of the hypothalamus, the central nucleus of the amygdala, Edinger-Westphal nucleus, lateral parabrachial nucleus, locus coeruleus, and nucleus of the solitary tract. GHB (500 mg/kg), but not baclofen (10 mg/kg), induced significant Fos expression in the median raphe nucleus and lateral habenula, while a higher dose of GHB (1000 mg/kg) induced additional Fos expression in the islands of Calleja, dentate gyrus (polymorphic layer) and arcuate nucleus, and in various regions implicated in rapid and non-rapid eye movement sleep (laterodorsal tegmental nucleus, tuberomammillary nucleus and the ventrolateral and anterodorsal preoptic nuclei). Surprisingly, Fos immunoreactivity was not observed with either GHB or baclofen in reward-relevant regions such as the nucleus accumbens, striatum and ventral tegmental area. Overall these results indicate a distinctive signature of brain activation with GHB that may be only partly due to GABA(B) receptor effects. This confirms a unique neuropharmacological profile for GHB and indicates key neural substrates that may underlie its characteristic influence on sleep, body temperature, sociability and endocrine function.

Gamma-hydroxybutyric acid in male and female cynomolgus monkeys trained to discriminate 1.0 or 2.0 g/kg ethanol

Gamma-hydroxybutyric acid has been proposed as a pharmacotherapy for alcoholism in part based on similar discriminative stimulus effects as ethanol. To date, drug discrimination studies with gamma-hydroxybutyric acid and ethanol have exclusively used rodents or pigeons as subjects. To evaluate possible differences between species, sex, and route of administration, this study investigated the substitution of gamma-hydroxybutyric acid (intragastrically or intramuscularly) for ethanol 30 or 60 min after administration in male (n=6) and female (n=7) cynomolgus monkeys trained to discriminate 1.0 and 2.0 g/kg ethanol. At least one dose of gamma-hydroxybutyric acid completely or partially substituted for ethanol in three of the 13 monkeys tested, with each case occurring in female monkeys. Ethanol-appropriate responding did not increase with gamma-hydroxybutyric acid dose. Monkeys were more sensitive to the response rate decreasing effects of gamma-hydroxybutyric acid administered intramuscularly compared with intragastrically. The lack of gamma-hydroxybutyric acid substitution for ethanol suggests that these drugs have different receptor bases for discrimination. Furthermore, the data do not strongly support shared discriminative stimulus effects as the rationale for gamma-hydroxybutyric acid pharmacotherapy for alcoholism.

New developments for the pharmacological treatment of alcohol withdrawal syndrome. A focus on non-benzodiazepine GABAergic medications

Alcohol withdrawal syndrome (AWS) can be a life-threatening condition affecting some alcohol-dependent patients who abruptly discontinue or decrease their alcohol consumption. The main objectives of the clinical management of AWS include: to decrease the severity of symptoms, prevent more severe withdrawal clinical manifestations and facilitate entry of the patient into a treatment program in order to attempt to achieve and maintain long-term abstinence from alcohol. At present, benzodiazepines represent the drugs of choice in the treatment of AWS. However, in line with the possible side effects and addictive properties related to benzodiazepine use, there is growing evidence to suggest that non-benzodiazepine GABAergic compounds represent promising medications in the treatment of alcohol-dependent patients. This review focuses on research into non-benzodiazepine GABAergic medications for the treatment of AWS. Among them, carbamazepine, gabapentin and valproic acid are the most studied. The studies on carbamazepine seem to be the most compelling. Preliminary data have also suggested the possible utility of baclofen and topiramate, although further evidence is needed. The promising results in terms of both safety and efficacy are reported. However, we also note the need of more methodologically controlled studies on a greater number of patients, involving more complicated forms of AWS.

New perspectives for the treatment of disorders of sleep and arousal

A variety of molecules with novel mechanisms of action are currently being evaluated for their potential as treatments for sleep disorders. The GABA-A receptor complex remains an important target for hypnotic drugs (eg gaboxadol, indiplon). However, drugs acting through histamine, calcium channels and serotonin receptors may also be of interest for the treatment of insomnia. In the case of the 5HT2A subtype of serotonin receptors, several molecules which improve sleep maintenance and modify sleep architecture by increasing slow wave sleep are currently being tested (eg eplivanserin). Two new drugs with efficacy in excessive sleepiness (modafinil, sodium oxybate) have improved the treatment of this condition. However, the mechanisms of action of these agents are poorly understood. The recent discovery of the hypocretin arousal system in the hypothalamus may aid the identification of additional new drugs. An agonist at receptors for the pineal hormone melatonin is available in some countries (ramelteon) but is currently used only for the treatment of insomnia associated with difficulties of sleep onset. Additional melatonin receptor agonists are being developed and may have potential for treating several conditions including circadian rhythm disorders and depression.

Sodium oxybate: a review of its use in the management of narcolepsy

Sodium oxybate (Xyrem) is the sodium salt of the CNS depressant gamma-hydroxybutyric acid (GHB) and is therefore subject to prescription restrictions. It is approved in the US for the treatment of cataplexy and excessive daytime sleepiness (EDS) in patients with narcolepsy, and in the EU for the treatment of narcolepsy with cataplexy. Sodium oxybate is generally well tolerated and effective in the treatment of symptoms of narcolepsy with cataplexy. While its short half-life necessitates twice-nightly administration, it is highly effective in reducing the frequency of cataplexy, improving sleep architecture and reducing EDS in patients with narcolepsy. Sodium oxybate therefore offers a valuable alternative or addition to the use of TCAs, SSRIs and stimulants in the treatment of the symptoms of narcolepsy including cataplexy and EDS.