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

Pathophysiological Models of Hypersomnolence Associated With Depression

Up to 25% of patients with depression experience hypersomnolence (e.g., excessive daytime sleepiness, hypersomnia, and/or sleep inertia), which is associated with treatment resistance, overall poorer outcomes, and safety concerns while driving. Hypersomnolence can result from various sleep/neurological disorders or side effects from medication but is often medically unexplained in depression. In this review, we aimed to summarize the different pathophysiological models of hypersomnolence in depression to discuss their impact on nosology and to foster the development of better tailored diagnostics and treatments. We identified several potential mechanisms underlying hypersomnolence including a daytime hypoactivity of dopaminergic and noradrenergic systems, nighttime GABA (gamma-aminobutyric acid) hypoactivation, hypoperfusion, and hypoconnectivity in the medial prefrontal cortex, as well as a longer circadian period and light hyposensitivity. In some patients with depression, nighttime hyperarousal can fragment sleep and result in a complaint of excessive daytime sleepiness, thus mimicking hypersomnolence. Others might adopt maladaptive behaviors such as spending excessive time in bed, a term coined clinophilia. Objective markers of hypersomnolence, such as ambulatory ad libitum polysomnography may facilitate distinguishing between conditions that mimic hypersomnolence. Our review identified several clinical targets for hypersomnolence in depression. Low-sodium oxybate, which is approved for idiopathic hypersomnia, needs additional study in patients with depression. Neuromodulation that targets prefrontal cortex anomalies should be systematically explored, while tailored light therapy protocols may mitigate light hyposensitivity. Additionally, cognitive behavioral therapy for hypersomnolence is being developed as a nonpharmacological adjunct to these treatments.

Efficacy and safety of sodium oxybate treatment in adults with narcolepsy and cataplexy: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Narcolepsy is a chronic illness characterized by excessive daytime sleepiness and cataplexy. Recently, sodium oxybate (SXB) has been the only effective drug in treating multiple symptoms of narcolepsy. Our study aims to assess the effectiveness and safety of SXB in treating narcolepsy.

METHOD

We searched four databases for eligible studies. Our primary outcome was to investigate the effectiveness of SXB through symptom improvement. For the secondary outcome, we assess its safety through the reported adverse events.

RESULT

Five RCTs were included. The SXB group had significantly improved weekly cataplexy attacks better than the placebo (MD = -5.04, 95% CI [-6.35, -3.72], P < 0.00001), also the improvement in the Maintenance of Wakefulness Test, and ESS was better in the SXB group with (MD = 4.66, 95% CI: [2.24, 7.07], p = 0.0002), (MD = -1.93, 95% CI: [-2.73, -1.13], p < 0.00001) respectively. CGI-I was observed to be significantly better in the SXB group with (RR = 2.15, 95% CI: [1.69, 2.73], p < 0.00001). The weekly cataplexy attack was significantly improved by the doses (4.5, 6, and 9 gm) in comparison with the placebo, with the 9-gm dose having the most beneficial effect. The improvements were significant only in SXB 9 gm in ESS and 6 and 9 gm in CGI-I.

CONCLUSION

SXB is an effective pharmacological treatment for the management of narcoleptic patients with cataplexy with an acceptable safety profile. Further studies with a large scale are needed to investigate and prove the efficacy and tolerability of SXB.

Metabolic Characteristics of Gut Microbiota and Insomnia: Evidence from a Mendelian Randomization Analysis

Insomnia is a common sleep disorder that significantly impacts individuals' sleep quality and daily life. Recent studies have suggested that gut microbiota may influence sleep through various metabolic pathways. This study aims to explore the causal relationships between the abundance of gut microbiota metabolic pathways and insomnia using Mendelian randomization (MR) analysis. This two-sample MR study used genetic data from the OpenGWAS database (205 gut bacterial pathway abundance) and the FinnGen database (insomnia-related data). We identified single nucleotide polymorphisms (SNPs) associated with gut bacterial pathway abundance as instrumental variables (IVs) and ensured their validity through stringent selection criteria and quality control measures. The primary analysis employed the inverse variance-weighted (IVW) method, supplemented by other MR methods, to estimate causal effects. The MR analysis revealed significant positive causal effects of specific carbohydrate, amino acid, and nucleotide metabolism pathways on insomnia. Key pathways, such as gluconeogenesis pathway (GLUCONEO.PWY) and TCA cycle VII acetate producers (PWY.7254), showed positive associations with insomnia (B > 0, p < 0.05). Conversely, pathways like hexitol fermentation to lactate, formate, ethanol and acetate pathway (P461.PWY) exhibited negative causal effects (B < 0, p < 0.05). Multivariable MR analysis confirmed the independent causal effects of these pathways (p < 0.05). Sensitivity analyses indicated no significant pleiotropy or heterogeneity, ensuring the robustness of the results. This study identifies specific gut microbiota metabolic pathways that play critical roles in the development of insomnia. These findings provide new insights into the biological mechanisms underlying insomnia and suggest potential targets for therapeutic interventions. Future research should further validate these causal relationships and explore how modulating gut microbiota or its metabolic products can effectively improve insomnia symptoms, leading to more personalized and precise treatment strategies.

Increase in NREM sleep slow waves following injections of sodium oxybate in the mouse cerebral cortex and the role of somatostatin-positive interneurons

The systemic administration of sodium oxybate (SXB), the sodium salt of gamma-hydroxybutyric acid, promotes slow wave activity (SWA, 0.5-4 Hz EEG power) and increases non-rapid eye movement (NREM) sleep. These effects are mediated by the widely expressed GABAb receptors, and thus, the brain areas targeted by SXB remain unclear. Because slow waves are mainly a cortical phenomenon, we tested here whether systemic SXB promotes SWA by acting directly on the cortex. Moreover, because somatostatin (SOM) + cortical interneurons play a key role in SWA generation, we also assessed their contribution to the effects of SXB. In adult SOM-Cre mice, the injection of SXB in left secondary motor cortex increased SWA during NREM sleep in the first 30 min post-injection (11 mice: either sex). SWA, the amplitude and frequency of the slow waves, and the frequency of the OFF periods increased ipsilaterally and contralaterally to the SXB injection in frontal and parietal cortex. All these changes disappeared when the intracortical injection of SXB was preceded by the chemogenetic inhibition of the SOM+ cells. Thus, SXB may promote the slow waves of NREM sleep, at least in part, by acting directly on the cortex, and this effect involves GABAergic SOM+ interneurons. Our working hypothesis is that SXB potentiates the ability of these cells to inhibit all other cortical cell types via a GABAb mechanism, thus promoting the transition from ON to OFF periods during NREM sleep.

Influence of glutamatergic and GABAergic neurotransmission on obstructive sleep apnea

Glutamate and γ-aminobutyric acid (GABA) are the two main neurotransmitters in the human brain. The balance between their excitatory and inhibitory functions is crucial for maintaining the brain's physiological functions. Disturbance of glutamatergic or GABAergic neurotransmission leads to serious health problems including neurodegeneration, affective and sleep disorders. Both GABA and glutamate are involved in the control of the sleep-wake cycle. The disturbances in their function may cause sleep and sleep-related disorders. Obstructive sleep apnea (OSA) is the most common sleep respiratory disorder and is characterized by repetitive collapse of the upper airway resulting in intermittent hypoxia and sleep fragmentation. The complex pathophysiology of OSA is the basis of the development of numerous comorbid diseases. There is emerging evidence that GABA and glutamate disturbances may be involved in the pathogenesis of OSA, as well as its comorbidities. Additionally, the GABA/glutamate targeted pharmacotherapy may also influence the course of OSA, which is important in the implementation of wildly used drugs including benzodiazepines, anesthetics, and gabapentinoids. In this review, we summarize current knowledge on the influence of disturbances in glutamatergic and GABAergic neurotransmission on obstructive sleep apnea.

Solriamfetol enhances wakefulness and improves cognition and anxiety in a murine model of OSA

BACKGROUND

Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH). Excessive daytime sleepiness (EDS) is a common consequence of OSA and is associated with cognitive deficits and anxiety. Modafinil (MOD) and Solriamfetol (SOL) are potent wake-promoting agents clinically used to improve wakefulness in OSA patients with EDS.

METHODS

Male C57Bl/6J mice were exposed to either IH or room air (RA) controls during the light phase for 16 weeks. Both groups were then randomly assigned to receive once-daily intraperitoneal injections of SOL (200 mg/kg), MOD (200 mg/kg) or vehicle (VEH) for 9 days while continuing IH exposures. Sleep/wake activity was assessed during the dark (active) phase. Novel object recognition (NOR), elevated-plus maze test (EPMT), and forced swim test (FST) were performed before and after drug treatment.

RESULTS

IH exposure increased dark phase sleep percentage and reduced wake bouts lengths and induced cognitive deficits and anxiogenic effects. Both SOL and MOD treatments decreased sleep propensity under IH conditions, but only SOL promoted improvements in NOR performance (explicit memory) and reduced anxiety-like behaviors.

CONCLUSION

Chronic IH, a hallmark feature of OSA, induces EDS in young adult mice that is ameliorated by both SOL and MOD. SOL, but not MOD, significantly improves IH-induced cognitive deficits and promotes anxiolytic effects. Thus, SOL could potentially benefit OSA patients beyond EDS management.

Pharmacologic Management of Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is defined as "irresistible sleepiness in a situation when an individual would be expected to be awake, and alert." EDS has been a big concern not only from a medical but also from a public health point of view. Patients with EDS have the possibility of falling asleep even when they should wake up and concentrate, for example, when they drive, play sports, or walk outside. In this article, clinical characteristics of common hypersomnia and pharmacologic treatments of each hypersomnia are described.

Calcium, Magnesium, Potassium, and Sodium Oxybates Oral Solution: A Lower-Sodium Alternative for Cataplexy or Excessive Daytime Sleepiness Associated with Narcolepsy

Lower-sodium oxybate (LXB) is an oxybate medication approved to treat cataplexy or excessive daytime sleepiness (EDS) in patients with narcolepsy 7 years of age and older in the United States. LXB was developed as an alternative to sodium oxybate (SXB), because the incidence of cardiovascular comorbidities is higher in patients with narcolepsy and there is an elevated cardiovascular risk associated with high sodium consumption. LXB has a unique formulation of calcium, magnesium, potassium, and sodium ions, containing 92% less sodium than SXB. Whereas the active oxybate moiety is the same for LXB and SXB, their pharmacokinetic profiles are not bioequivalent; therefore, a phase 3 trial in participants with narcolepsy was conducted for LXB. This review summarizes the background on oxybate as a therapeutic agent and its potential mechanism of action on the gamma-aminobutyric acid type B (GABA_B) receptor at noradrenergic and dopaminergic neurons, as well as at thalamocortical neurons. The rationale leading to the development of LXB as a lower-sodium alternative to SXB and the key efficacy and safety data supporting its approval for both adult and pediatric patients with narcolepsy are also discussed. LXB was approved in August 2021 in the United States for the treatment of idiopathic hypersomnia in adults. Potential future developments in the field of oxybate medications may include novel formulations and expanded indications for other diseases.

Safety and efficacy of lower-sodium oxybate in adults with idiopathic hypersomnia: a phase 3, placebo-controlled, double-blind, randomised withdrawal study

BACKGROUND

Idiopathic hypersomnia is a central hypersomnolence disorder mainly characterised by excessive daytime sleepiness, with prolonged night-time sleep and pronounced sleep inertia. Until August, 2021, no medication had regulatory approval for the treatment of idiopathic hypersomnia. This study aimed to evaluate the safety and efficacy of lower-sodium oxybate in idiopathic hypersomnia.

METHODS

This was a phase 3, multicentre (50 specialist sleep centres; six EU countries and the USA), placebo-controlled, double-blind, randomised withdrawal study. Participants (aged 18-75 years) with idiopathic hypersomnia (meeting criteria from the International Classification of Sleep Disorders, 2nd or 3rd editions) began lower-sodium oxybate treatment (oral solution once or twice nightly) in an open-label titration and optimisation period (10-14 weeks), followed by a 2-week, open-label, stable-dose period. After these open-label periods, participants were randomised (1:1) by means of an interactive web recognition system, stratified by participants' baseline medication use, to either placebo or lower-sodium oxybate (individually optimised dose; range 2·5-9·0 g/night) during a 2-week, double-blind, randomised withdrawal period. To maintain masking of treatment assignment, placebo and lower-sodium oxybate oral solutions were matched in volume, appearance, and taste. During the double-blind, randomised withdrawal period, participants and investigators were unaware of treatment assignments. The primary efficacy endpoint was change in Epworth Sleepiness Scale (ESS) score from the end of the stable-dose period to the end of the double-blind, randomised withdrawal period, which was assessed in the modified intention-to-treat population (defined as all participants who were randomly assigned, took at least one dose of study medication during the double blind, randomised withdrawal period, and had at least one set of post-randomisation assessments for the primary or key secondary endpoints). Adverse events were assessed in the safety population (defined as all participants who took at least one dose of study medication). This study is registered at ClinicalTrials.gov, NCT03533114, and at EU Clinical Trials, 2018-001311-79, and is complete.

FINDINGS

Between Nov 27, 2018, and March 6, 2020, 154 participants were enrolled and comprised the safety population. ESS scores decreased from a mean of 15·7 (SD 3·8) at baseline to 6·1 (4·0) by the end of the stable-dose period. After the open-label periods, 115 participants were randomly assigned either placebo (n=59) or lower-sodium oxybate (n=56) and comprised the modified intention-to-treat population. During the double-blind, randomised withdrawal period, ESS scores increased (worsened) in participants randomly assigned to placebo but remained stable in those assigned to lower-sodium oxybate (least squares mean difference -6·5; 95% CI -8·0 to -5·0; p<0·0001). Treatment-emergent adverse events included nausea (34 [22%] of 154), headache (27 [18%] of 154), dizziness (19 [12%] of 154), anxiety (17 [11%] 154), and vomiting (17 [11%] 154). No deaths were reported during the study.

INTERPRETATION

Lower-sodium oxybate treatment resulted in a clinically meaningful improvement in idiopathic hypersomnia symptoms, with an overall safety profile consistent with that reported for narcolepsy. Lower-sodium oxybate was approved in August, 2021, by the US Food and Drug Administration for the treatment of idiopathic hypersomnia in adults.

FUNDING

Jazz Pharmaceuticals.

Determination of endogenous GHB levels in chest and pubic hair

Endogenous nature of GHB represents a critical issue for forensic toxicologists, especially in alleged sexual assaults. Therefore, discrimination between physiologically and additional amounts from exogenous sources of such a substance must be effective and reliable in order to avoid severe misinterpretation. This study aimed to quantify the GHB baseline concentrations in chest and pubic hairs collected from 105 healthy volunteers, non-consumers of any drugs of abuse. The final scope was to investigate if these keratin matrices could represent valid alternative to scalp hair when not available. Moreover, we also evaluated the age and gender influences on the GHB baseline levels. 25 mg of hair were incubated overnight with NaOH at 56 °C. After acidification with H₂SO₄, the solution was liquid-liquid extracted with ethyl acetate and a trimethylsilyl derivatization was then achieved. Analysis was performed in gas chromatography-mass spectrometry in single ion monitoring mode (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in "blank" hair was estimated by the standard addition method (0.301 for chest hair and 0.235 ng/mg for pubic hair). GHB concentration ranged from 0.205 to 1.511 ng/mg for chest hair and from 0.310 to 1.913 ng/mg for pubic hair. These values were consistent with previous studies on scalp hair and on pubic hair. Unfortunately, research on chest hair is not available in literature. T-Test and Linear Regression highlighted no statistically significant differences for the two matrices and for all age/gender sub-groups. However, further studies are required to estimate a reliable cut-off value for these keratin matrices. For the first time, we demonstrated the suitability of chest and pubic hair to detect endogenous levels of GHB.

Excessive Daytime Sleepiness: A Clinical Review

Excessive daytime sleepiness (EDS) is a highly prevalent condition that is associated with significant morbidity. The causes of EDS are varied, and include inadequate sleep, sleep disordered breathing, circadian rhythm sleep-wake disorders, and central disorders of hypersomnolence (narcolepsy, idiopathic hypersomnia, and Kleine-Levin syndrome). Additionally, EDS could represent a symptom of an underlying medical or psychiatric disorder. Assessment of EDS includes a thorough sleep, medical, and psychiatric history, targeted clinical examination, and appropriate use of actigraphy to measure sleep duration and sleep-wake patterns, polysomnography to assess for associated conditions such as sleep-related breathing disorders or other factors that might disrupt nighttime sleep, multiple sleep latency testing to ascertain objective sleepiness and diagnose central disorders of hypersomnolence, and measurement of cerebrospinal fluid hypocretin-1 concentration. Treatment of EDS secondary to central disorders of hypersomnolence is primarily pharmacologic with wakefulness-promoting agents such as modafinil, stimulants such as methylphenidate and amphetamines, and newer agents specifically designed to improve wakefulness; behavioral interventions can provide a useful adjunct to pharmacologic treatment. When excessive sleepiness is secondary to other conditions, the treatment should focus on targeting the primary disorder. This review discusses current epidemiology, provides guidance on clinical assessments and testing, and discusses the latest treatment options. For this review, we collated the latest evidence using the search terms excessive sleepiness, hypersomnia, hypersomnolence, treatment from PubMed and MEDLINE and the latest practice parameters from the American Academy of Sleep Medicine.

Evaluation of the abuse potential of pitolisant, a selective H3-receptor antagonist/inverse agonist, for the treatment of adult patients with narcolepsy with or without cataplexy

Objectives

To evaluate the human abuse potential of pitolisant, a selective histamine 3 (H₃)-receptor antagonist/inverse agonist recently approved by the US Food and Drug Administration for the treatment of excessive daytime sleepiness in adult patients with narcolepsy.

Methods

Nondependent, recreational stimulant users able to distinguish phentermine HCl 60 mg from placebo in a drug discrimination test were randomized in a four-period, double-blind, crossover design to receive single doses of pitolisant 35.6 mg (therapeutic dose), pitolisant 213.6 mg (supratherapeutic dose), phentermine HCl 60 mg, and placebo. The primary endpoint was maximum effect (E_max) on the 100-point Drug Liking (“at this moment”) visual analog scale.

Results

In 38 study completers (73.7% male; 65.8% white; mean age, 33.3 years), mean Drug Liking E_max was significantly greater for phentermine versus pitolisant 35.6 mg (mean difference, 21.4; p < 0.0001) and pitolisant 213.6 mg (mean difference, 19.7; p < 0.0001). Drug Liking E_max was similar for pitolisant (both doses) and placebo. Similarly, for key secondary measures of Overall Drug Liking and willingness to Take Drug Again, mean E_max scores were significantly greater for phentermine versus pitolisant (both doses) and similar for pitolisant (both doses) versus placebo. The incidence of adverse events was 82.1% after phentermine HCl 60 mg, 72.5% after pitolisant 213.6 mg, 47.5% after pitolisant 35.6 mg, and 48.8% after placebo administration.

Conclusions

In this study, pitolisant demonstrated significantly lower potential for abuse compared with phentermine and an overall profile similar to placebo; this suggests a low risk of abuse for pitolisant.

Clinical Trial Registration

ClinicalTrials.gov NCT03152123. Determination of the abuse potential of pitolisant in healthy, nondependent recreational stimulant users. https://clinicaltrials.gov/ct2/show/NCT03152123.

Pharmacologic Management of Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is related to medical and social problems, including mental disorders, physical diseases, poor quality of life, and so forth. According to the International Classification of Sleep Disorders, Third Edition, diseases that result from EDS are narcolepsy type 1, narcolepsy type 2, idiopathic hypersomnia, hypersomnia due to a medical disorder, and others. EDS is usually treated using amphetamine-like central nervous system stimulants or modafinil and its R-enantiomer, armodafinil, wake-promoting compounds unrelated to amphetamines; a variety of new drugs are under development. The side effects of some stimulants are potent and careful selection and management are required.

Knowledge Gaps in the Perioperative Management of Adults With Narcolepsy: A Call for Further Research

There is increasing awareness that sleep disorders may be associated with increased perioperative risk. The Society of Anesthesia and Sleep Medicine created the Narcolepsy Perioperative Task Force: (1) to investigate the current state of knowledge of the perioperative risk for patients with narcolepsy, (2) to determine the viability of developing perioperative guidelines for the management of patients with narcolepsy, and (3) to delineate future research goals and clinically relevant outcomes. The Narcolepsy Perioperative Task Force established that there is evidence for increased perioperative risk in patients with narcolepsy; however, this evidence is sparse and based on case reviews, case series, and retrospective reviews. Mechanistically, there are a number of potential mechanisms by which patients with narcolepsy could be at increased risk for perioperative complications. These include aggravation of the disease itself, dysautonomia, narcolepsy-related medications, anesthesia interactions, and withdrawal of narcolepsy-related medications. At this time, there is inadequate research to develop an expert consensus or guidelines for the perioperative management of patients with narcolepsy. The paucity of available literature highlights the critical need to determine if patients with narcolepsy are at an increased perioperative risk and to establish appropriate research protocols and clearly delineated patient-centered outcomes. There is a real need for collaborative research among sleep medicine specialists, surgeons, anesthesiologists, and perioperative providers. This future research will become the foundation for the development of guidelines, or at a minimum, a better understanding how to optimize the perioperative care of patients with narcolepsy.

Update on the pharmacologic management of narcolepsy: mechanisms of action and clinical implications

Narcolepsy is a chronic, debilitating neurological disorder of sleep-wake state instability. This instability underlies all narcolepsy symptoms, including excessive daytime sleepiness (EDS), symptoms of rapid eye movement (REM) sleep dysregulation (ie, cataplexy, hypnagogic/hypnopompic hallucinations, sleep paralysis), and disrupted nighttime sleep. Several neurotransmitter systems promote wakefulness, and various neural pathways are involved in regulating REM sleep-related muscle atonia, providing multiple targets for pharmacologic intervention to reduce EDS and cataplexy. Medications approved by the US Food and Drug Administration (FDA) for the treatment of EDS in narcolepsy include traditional stimulants (eg, amphetamines, methylphenidate), wake-promoting agents (eg, modafinil, armodafinil), and solriamfetol, which mainly act on dopaminergic and noradrenergic pathways. Sodium oxybate (thought to act via GABA_B receptors) is FDA-approved for the treatment of EDS and cataplexy. Pitolisant, a histamine 3 (H₃)-receptor antagonist/inverse agonist, is approved by the European Medicines Agency (EMA) for the treatment of narcolepsy with or without cataplexy in adults and by the FDA for the treatment of EDS in adults with narcolepsy. Pitolisant increases the synthesis and release of histamine in the brain and modulates the release of other neurotransmitters (eg, norepinephrine, dopamine). Antidepressants that inhibit reuptake of serotonin and/or norepinephrine are widely used off label to manage cataplexy. In many patients with narcolepsy, combination treatment with medications that act via different neural pathways is necessary for optimal symptom management. Mechanism of action, pharmacokinetics, and abuse potential are important considerations in treatment selection and subsequent medication adjustments to maximize efficacy and mitigate adverse effects in the treatment of patients with narcolepsy.

Sleep as a Therapeutic Target in the Aging Brain

Sleep is a behavioral phenomenon conserved among mammals and some invertebrates, yet the biological functions of sleep are still being elucidated. In humans, sleep time becomes shorter, more fragmented, and of poorer quality with advancing age. Epidemiologically, the development of age-related neurodegenerative diseases such as Alzheimer's and Parkinson's disease is associated with pronounced sleep disruption, whereas emerging mechanistic studies suggest that sleep disruption may be causally linked to neurodegenerative pathology, suggesting that sleep may represent a key therapeutic target in the prevention of these conditions. In this review, we discuss the physiology of sleep, the pathophysiology of neurodegenerative disease, and the current literature supporting the relationship between sleep, aging, and neurodegenerative disease.

Alcohol-related chronic exocrine pancreatic insufficiency: diagnosis and therapeutic management. A proposal for treatment by the Italian Association for the Study of the Pancreas (AISP) and the Italian Society of Alcohology (SIA)

Current estimates of the prevalence of chronic pancreatitis, one of the most common causes of exocrine pancreatic insufficiency, are in the range of 3-10 per 100,000 people in many parts of the world. Alcohol consumption is a very important risk factor for exocrine pancreatic insufficiency and is involved in nearly half of all cases. The main hypothesis regarding the role of chronic alcohol consumption in pancreatitis is that there must be additional environmental or genetic risk factors involved for ongoing damage to occur. Treatment of patients with alcohol-related exocrine pancreatic insufficiency is complex, as the patient has two concomitant pathologies, alcohol-use disorder (AUD) and exocrine pancreatic insufficiency/chronic pancreatitis. Alcohol abstinence is the starting point for treatment, although even this along with the most advanced therapies allow only a slowdown in progression rather than restoration of function. This position paper of the Italian Association for the Study of the Pancreas and the Italian Society of Alcohology provides an overview of the pathogenesis of alcohol-related pancreatitis and discuss diagnostic issues. Treatment options for both exocrine pancreatic insufficiency/chronic pancreatitis (with a focus on pancreatic enzyme replacement therapy) and AUD (acamprosate, disulfiram, oral naltrexone, long-acting injectable naltrexone, sodium oxybate, nalmefene, baclofen, and psychosocial interventions) are also reviewed.

Effect of sodium oxybate, modafinil, and their combination on disrupted nighttime sleep in narcolepsy

OBJECTIVE

To assess the effects of three narcolepsy treatment modalities on sleep stage shifts associated with disrupted nighttime sleep (DNS) using data from a clinical trial.

METHODS

Polysomnograms were reviewed from 155 patients (who had these data available at baseline and 8 weeks) of the 278 patients who were randomized to placebo, 9-g sodium oxybate (SXB)/nightly, 200-600 mg/d modafinil, or SXB + modafinil. Major outcomes of these post hoc analyses, analyzed using analysis of covariance, were change from baseline in number of shifts from Stages N2/3/rapid eye movement (REM) to Stage N1/Wake, and from Stage N1/Wake to REM. Sleep quality was evaluated using the sleep-quality question from the Pittsburgh Sleep Quality Index.

RESULTS

SXB alone or in combination with modafinil significantly decreased the number of shifts from Stage N2/3/REM to Stage N1/Wake (p < 0.01); least-squares mean change in number of shifts from baseline was -0.6, -16.5, 1.8, and -13.7 in the placebo, SXB, modafinil and SXB + modafinil groups, respectively. A similar pattern was observed for changes in shifts from REM to Stage N1/Wake and from Stage N1/Wake to REM. Relative to placebo, sleep quality significantly improved with SXB and SXB + modafinil (p ≤ 0.05) but not with modafinil alone.

CONCLUSION

These results show that SXB with and without modafinil significantly consolidated sleep and improved patient-reported sleep quality relative to placebo. In contrast, no such effects were observed with modafinil alone, suggesting a specific effect of SXB on DNS in addition to its effect on daytime sleepiness. CLINICALTRIALS.

GOV IDENTIFIER

NCT00066170.

Pharmacologic Management of Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is related to medical and social problems, including mental disorders, physical diseases, poor quality of life, and so forth. According to the International Classification of Sleep Disorders, Third Edition, diseases that result from EDS are narcolepsy type 1, narcolepsy type 2, idiopathic hypersomnia, hypersomnia due to a medical disorder, and others. EDS is usually treated using amphetamine-like central nervous system stimulants or modafinil and its R-enantiomer, armodafinil, wake-promoting compounds unrelated to amphetamines; a variety of new drugs are under development. The side effects of some stimulants are potent and careful selection and management are required.

Safety and efficacy of pitolisant on cataplexy in patients with narcolepsy: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Histaminergic neurons are crucial to maintain wakefulness, but their role in cataplexy is unknown. We assessed the safety and efficacy of pitolisant, a histamine H3 receptor inverse agonist, for treatment of cataplexy in patients with narcolepsy.

METHODS

For this randomised, double-blind, placebo-controlled trial we recruited patients with narcolepsy from 16 sleep centres in nine countries (Bulgaria, Czech Republic, Hungary, Macedonia, Poland, Russia, Serbia, Turkey, and Ukraine). Patients were eligible if they were aged 18 years or older, diagnosed with narcolepsy with cataplexy according to version two of the International Classification of Sleep Disorders criteria, experienced at least three cataplexies per week, and had excessive daytime sleepiness (defined as an Epworth Sleepiness Scale score ≥12). We used a computer-generated sequence via an interactive web response system to randomly assign patients to receive either pitolisant or placebo once per day (1:1 ratio). Randomisation was done in blocks of four. Participants and investigators were masked to treatment allocation. Treatment lasted for 7 weeks: 3 weeks of flexible dosing decided by investigators according to efficacy and tolerance (5 mg, 10 mg, or 20 mg oral pitolisant), followed by 4 weeks of stable dosing (5 mg, 10 mg, 20 mg, or 40 mg). The primary endpoint was the change in the average number of cataplexy attacks per week as recorded in patient diaries (weekly cataplexy rate [WCR]) between the 2 weeks of baseline and the 4 weeks of stable dosing period. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01800045.

FINDINGS

The trial was done between April 19, 2013, and Jan 28, 2015. We screened 117 patients, 106 of whom were randomly assigned to treatment (54 to pitolisant and 52 to placebo) and, after dropout, 54 patients from the pitolisant group and 51 from the placebo group were included in the intention-to-treat analysis. The WCR during the stable dosing period compared with baseline was decreased by 75% (WCR_final=2·27; WCR_baseline=9·15; WCR_{final/baseline}=0·25) in patients who received pitolisant and 38% (WCR_final=4·52; WCR_baseline=7·31; WCR_{final/baseline}=0·62) in patients who received placebo (rate ratio 0·512; 95% CI 0·43-0·60, p<0·0001). Treatment-related adverse events were significantly more common in the pitolisant group than in the placebo group (15 [28%] of 54 vs 6 [12%] of 51; p=0·048). There were no serious adverse events, but one case of severe nausea in the pitolisant group. The most frequent adverse events in the pitolisant group (headache, irritability, anxiety, and nausea) were mild or moderate except one case of severe nausea. No withdrawal syndrome was detected following pitolisant treatment; one case was detected in the placebo group.

INTERPRETATION

Pitolisant was well tolerated and efficacious in reducing cataplexy. If confirmed in long-term studies, pitolisant might constitute a useful first-line therapy for cataplexy in patients with narcolepsy, for whom there are currently few therapeutic options.

FUNDING

Bioprojet, France.

Fibromyalgia syndrome: novel therapeutic targets

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread pain and tenderness, accompanied by disturbed sleep, chronic fatigue and multiple additional functional symptoms. FMS continues to pose an unmet need regarding pharmacological treatment and many patients fail to achieve sufficient relief from existing treatments. As FMS is considered to be a condition in which pain amplification occurs within the CNS, therapeutic interventions, both pharmacological and otherwise, have revolved around attempts to influence pain processing in the CNS. In the current review, we present an update on novel targets in the search for effective treatment of FMS.

Management of fibromyalgia syndrome in 2016

Fibromyalgia syndrome is a chronic pain disorder and defies definitively efficacious therapy. In this review, we summarize the results from the early treatment research as well as recent research evaluating the pharmacological, interventional and nonpharmacological therapies. We further discuss future directions of fibromyalgia syndrome management; we specifically focus on the issues that are associated with currently available treatments, such as the need for personalized approach, new technologically oriented and interventional treatments, the importance of understanding and harnessing placebo effects and enhancement of patient engagement in therapy.

Sodium oxybate plus nalmefene for the treatment of alcohol use disorder: A case series

The treatment of alcohol use disorder still remains a challenge. The efficacy of the combined pharmacological treatment for alcohol use disorder has been widely investigated with controversial results. The aim of our case series was to investigate the effect of nalmefene in patients not responding to sodium oxybate therapy. We describe seven cases of consecutive patients affected by alcohol use disorder, and treated with sodium oxybate (50 mg/kg per day) who did not achieve complete alcohol abstinence after at least one month of pharmacological treatment. Then, in partial- and non-responder patients to sodium oxybate treatment, administration of nalmefene, 18 mg as needed, was commenced. Our data show that, during the first month of the combined treatment of sodium oxybate plus nalmefene, patients were able to achieve alcohol abstinence (two patients), to suppress (five cases) or reduce (two patients) episodes of heavy drinking days, and to suppress the onset of craving for sodium oxybate (one patient). Likely, nalmefene may act in modulating the excessive reward effect of sodium oxybate, which may be responsible for the persistence of alcohol intake and for the onset of craving for sodium oxybate. However, controlled clinical trials to confirm the safety and efficacy of sodium oxybate plus nalmefene in treating alcohol use disorder are warranted.

A Brief Up-Date of the Use of Sodium Oxybate for the Treatment of Alcohol Use Disorder

The treatment of alcohol use disorder (AUD) with sodium oxybate (SMO) or gamma-hydroxybutyric acid (GHB) was introduced in Italy and Austria more than 20 years and 15 years ago, respectively, and it is now widely employed to treat alcohol withdrawal syndrome (AWS) and to maintain alcohol abstinence. These indications derive from its similar structure to the inhibitory neurotransmitter γ-amino-butyric acid (GABA), exerting an ethanol-mimicking effect, because it binds to GABAB receptors. Craving for, and abuse of, SMO remain a controversial issue; even though these unfavorable effects are evident in poly-drug addicted patients and in those with psychiatric diagnosis of borderline personality disorder. In addition, despite cases of severe intoxication and deaths being widely documented when GHB is used as "street drug"; its clinical use remains safe. Thus, the aim of the present review is to examine the role of SMO in the treatment of AUD, its possible implications in reducing alcohol consumption, and cases of abuse, and severe intoxication due to SMO during its clinical use in the treatment of AUD.

GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome

The illicit recreational drug of abuse, γ-hydroxybutyrate (GHB) is a potent central nervous system depressant and is often encountered during forensic investigations of living and deceased persons. The sodium salt of GHB is registered as a therapeutic agent (Xyrem®), approved in some countries for the treatment of narcolepsy-associated cataplexy and (Alcover®) is an adjuvant medication for detoxification and withdrawal in alcoholics. Trace amounts of GHB are produced endogenously (0.5-1.0 mg/L) in various tissues, including the brain, where it functions as both a precursor and a metabolite of the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). Available information indicates that GHB serves as a neurotransmitter or neuromodulator in the GABAergic system, especially via binding to the GABA-B receptor subtype. Although GHB is listed as a controlled substance in many countries abuse still continues, owing to the availability of precursor drugs, γ-butyrolactone (GBL) and 1,4-butanediol (BD), which are not regulated. After ingestion both GBL and BD are rapidly converted into GHB (t½ ~1 min). The Cmax occurs after 20-40 min and GHB is then eliminated from plasma with a half-life of 30-50 min. Only about 1-5% of the dose of GHB is recoverable in urine and the window of detection is relatively short (3-10 h). This calls for expeditious sampling when evidence of drug use and/or abuse is required in forensic casework. The recreational dose of GHB is not easy to estimate and a concentration in plasma of ~100 mg/L produces euphoria and disinhibition, whereas 500 mg/L might cause death from cardiorespiratory depression. Effective antidotes to reverse the sedative and intoxicating effects of GHB do not exist. The poisoned patients require supportive care, vital signs should be monitored and the airways kept clear in case of emesis. After prolonged regular use of GHB tolerance and dependence develop and abrupt cessation of drug use leads to unpleasant withdrawal symptoms. There is no evidence-based protocol available to deal with GHB withdrawal, apart from administering benzodiazepines.

Coupling of Thalamocortical Sleep Oscillations Are Important for Memory Consolidation in Humans

Sleep, specifically non-rapid eye movement (NREM) sleep, is thought to play a critical role in the consolidation of recent memories. Two main oscillatory activities observed during NREM, cortical slow oscillations (SO, 0.5–1.0Hz) and thalamic spindles (12–15Hz), have been shown to independently correlate with memory improvement. Yet, it is not known how these thalamocortical events interact, or the significance of this interaction, during the consolidation process. Here, we found that systemic administration of the GABAergic drug (zolpidem) increased both the phase-amplitude coupling between SO and spindles, and verbal memory improvement in humans. These results suggest that thalamic spindles that occur during transitions to the cortical SO Up state are optimal for memory consolidation. Our study predicts that the timely interactions between cortical and thalamic events during consolidation, contribute to memory improvement and is mediated by the level of inhibitory neurotransmission.

GABA(B) receptor-mediated activation of astrocytes by gamma-hydroxybutyric acid

The gamma-aminobutyric acid (GABA) metabolite gamma-hydroxybutyric acid (GHB) shows a variety of behavioural effects when administered to animals and humans, including reward/addiction properties and absence seizures. At the cellular level, these actions of GHB are mediated by activation of neuronal GABA_B receptors (GABA_BRs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABA_A and GABA_BRs, here we investigated the action of GHB on astrocytes on the ventral tegmental area (VTA) and the ventrobasal (VB) thalamic nucleus, two brain areas involved in the reward and proepileptic action of GHB, respectively, and compared it with that of the potent GABA_BR agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED₅₀: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca²⁺ in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABA_BRs and mediated by Ca²⁺ release from intracellular store release. In contrast, prolonged GHB and baclofen exposure caused a reduction in spontaneous astrocyte activity and glutamate release from VTA astrocytes. These findings have key (patho)physiological implications for our understanding of the addictive and proepileptic actions of GHB.

Treatment paradigms for cataplexy in narcolepsy: past, present, and future

Cataplexy is defined as episodes of sudden loss of voluntary muscle tone triggered by emotions generally lasting <2 minutes. Cataplexy is most commonly associated with and considered pathognomonic for narcolepsy, a sleep disorder affecting ~0.05% of the general population. Knowledge of the pathophysiology of cataplexy has advanced through study of canine, murine, and human models. It is now generally considered that loss of signaling by hypothalamic hypocretin/orexin-producing neurons plays a key role in the development of cataplexy. Although the cause of hypocretin/orexin neuron loss in narcolepsy with cataplexy is unknown, an autoimmune etiology is widely hypothesized. Despite these advances, a literature review shows that treatment of cataplexy remains limited. Multiple classes of antidepressants have been commonly used off-label for cataplexy in narcolepsy and are suggested for this use in expert consensus guidelines based on traditional practice, case reports, and small trials. However, systematic research evidence supporting antidepressants for cataplexy is lacking. The single pharmacotherapy indicated for cataplexy and the guideline-recommended first-line treatment in Europe and the US is sodium oxybate, the sodium salt of gamma-hydroxybutyrate. Clinical trial evidence of its efficacy and safety in cataplexy is robust, and it is hypothesized that its therapeutic effects may occur through gamma-aminobutyric acid receptor type B-mediated effects at noradrenergic, dopaminergic, and thalamocortical neurons. Additional possible mechanisms for cataplexy therapy suggested by preliminary research include antagonism of the histamine H3 autoreceptor with pitolisant and intravenous immunoglobulin therapy for amelioration of the presumed autoimmune-mediated hypocretin/orexin cell loss. Further research and development of therapeutic approaches to cataplexy are needed.

Pharmacological management of alcohol dependence: from mono-therapy to pharmacogenetics and beyond

Almost 10% of the world's population is affected by alcohol use disorders, and the treatment of alcohol dependence (AD) still remains a challenge. Patients with AD can differ in many traits. Three drugs (disulfiram, naltrexone, and acamprosate) have been approved by the FDA for the treatment of AD, and in some European countries sodium oxybate is also approved for this purpose. Combined pharmacological therapy has not provided such convincing results. Considering the fact that the "ideal" and effective drug for all types of alcoholic patients does not exists, the future challenge will be to identify a personalized approach. Recent data has shown that this objective can be achieved by investigating the genetic variability of the patient. Moreover, the use of replacement molecules can probably be considered an advantageous therapeutic opportunity (i.e. sodium oxybate). In addition, reduction of alcohol consumption is increasingly accepted as a viable treatment goal, and the use of nalmefene "as-needed" (a pharmacological approach similar to naltrexone, but, possibly, with lower hepatotoxicity) may help in the treatment of AD. Thus, it is important to stress that a pharmacological approach to treat AD should be preceded by the definition of patient characteristics; this may help in the choice of the most appropriate drug and it can be done more easily when more pharmacological options approved for the treatment of AD are also available.

Sodium oxybate in maintaining alcohol abstinence in alcoholic patients according to Lesch typologies: a pilot study

Sodium oxybate (SO) is a γ-amino-butyric acid (GABA)-ergic drug currently used for the treatment of alcohol dependence (AD) in some European countries. The aim of this study was to describe the effect of SO administration in alcoholics classified according to Lesch alcoholism typology (LAT). Forty-eight patients were enrolled and classified into four groups according to LAT. All patients were treated with oral SO (50 mg/kg of body weight t.i.d.) for 12 weeks. All patients significantly reduced their alcohol intake (p<0.001). Alcohol abstinence during the 12 weeks of treatment did not differ between the four groups at the end of treatment. Craving for SO did not significantly differ amongst groups; cases of SO abuse were very limited and were observed in almost 10% of patients. In conclusion, our study showed an overall efficacy of SO in the treatment of AD irrespective of LAT categories. However, our results confirm that alcoholics with psychiatric co-morbidity, particularly with a borderline personality disorder of Axis II, are at a greater risk of developing craving for and abuse of the drug: until craving for alcohol and craving for SO are characterized in depth, SO should be used with caution in these patients.

Management of fibromyalgia syndrome: review of evidence

Fibromyalgia syndrome (FMS) is a common chronic musculoskeletal pain disorder of unknown etiology and characterized by generalized body pain, hyperalgesia, and other functional and emotional comorbidities. Despite extensive research, no treatment modality is effective for all FMS patients. In this paper, we briefly review the history of FMS and diagnostic criteria, and potential pathophysiological mechanisms including central pain modulation, neurotransmitters, sympatho-adrenal and hypothalamic-pituitary-adrenal systems and peripheral muscle issues. The primary focus of the paper is to review treatment options for managing fibromyalgia symptoms. We will discuss FDA-approved medications and other pharmacologic agents, and non-pharmacologic treatments that have shown promising effects.

Managing insomnia: an overview of insomnia and pharmacologic treatment strategies in use and on the horizon

This review explores basic sleep physiology, the mechanism of action for each class of hypnotic agents, their clinical application based on pharmacodynamic and pharmacokinetic factors, and potential pharmacologic sleep-inducing mechanisms of future hypnotics. The paper challenges the reader to understand the neuroscientific basis of insomnia and use this knowledge to guide prescription of hypnotic agents. Currently indicated hypnotic agents are discussed with regard to their mechanism of drug action and clinical application. A broader discussion is developed throughout this paper regarding other non-indicated agents that may improve sleep and describing newer pharmacological treatments that may become available in the future for use in sleep disorders and their comorbid conditions.

Plasma total ghrelin and leptin levels in human narcolepsy and matched healthy controls: basal concentrations and response to sodium oxybate

STUDY OBJECTIVES

Narcolepsy is caused by a selective loss of hypocretin neurons and is associated with obesity. Ghrelin and leptin interact with hypocretin neurons to influence energy homeostasis. Here, we evaluated whether human hypocretin deficiency, or the narcolepsy therapeutic agent sodium oxybate, alter the levels of these hormones.

METHODS

Eight male, medication free, hypocretin deficient, narcolepsy with cataplexy patients, and 8 healthy controls matched for age, sex, body mass index (BMI), waisttohip ratio, and body fat percentage were assessed. Blood samples of total ghrelin and leptin were collected over 24 hours at 60 and 20-min intervals, respectively, during 2 study occasions: baseline, and during the last night of 5 consecutive nights of sodium oxybate administration (2 × 3.0 g/night).

RESULTS

At baseline, mean 24-h total ghrelin (936 ± 142 vs. 949 ± 175 pg/mL, p = 0.873) and leptin (115 ± 5.0 vs. 79.0 ± 32 mg/L, p = 0.18) levels were not different between hypocretin deficient narcolepsy patients and controls. Furthermore, sodium oxybate did not significantly affect the plasma concentration of either one of these hormones.

CONCLUSIONS

The increased BMI of narcolepsy patients is unlikely to be mediated by hypocretin deficiency-mediated alterations in total ghrelin or leptin levels. Thus, the effects of these hormones on hypocretin neurons may be mainly unidirectional. Although sodium oxybate may influence body weight, the underlying mechanism is unlikely to involve changes in total ghrelin or leptin secretion.

The psychostimulant modafinil enhances gap junctional communication in cortical astrocytes

Sleep-wake cycle is characterized by changes in neuronal network activity. However, for the last decade there is increasing evidence that neuroglial interaction may play a role in the modulation of sleep homeostasis and that astrocytes have a critical impact in this process. Interestingly, astrocytes are organized into communicating networks based on their high expression of connexins, which are the molecular constituents of gap junction channels. Thus, neuroglial interactions should also be considered as the result of the interplay between neuronal and astroglial networks. Here, we investigate the effect of modafinil, a wakefulness-promoting agent, on astrocyte gap junctional communication. We report that in the cortex modafinil injection increases the expression of mRNA and protein of connexin 30 but not those of connexin 43, the other major astroglial connexin. These increases are correlated with an enhancement of intercellular dye coupling in cortical astrocytes, which is abolished when neuronal activity is silenced by tetrodotoxin. Moreover, gamma-hydroxybutyric acid, which at a millimolar concentration induces sleep, has an opposite effect on astroglial gap junctions in an activity-independent manner. These results support the proposition that astroglia may play an important role in complex physiological brain functions, such as sleep regulation, and that neuroglial networking interaction is modified during sleep-wake cycle. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.

Feasibility of following up gamma-hydroxybutyric acid concentrations in sodium oxybate (Xyrem®)-treated narcoleptic patients using dried blood spot sampling at home: an exploratory study

BACKGROUND

Gamma-hydroxybutyric acid (GHB), well known as a party drug, especially in Europe, is also legally used (sodium oxybate, Xyrem(®)) to treat a rare sleep disorder, narcolepsy with cataplexy. This exploratory study was set up to measure GHB concentrations in dried blood spots (DBS) collected by narcoleptic patients treated with sodium oxybate. Intra- and inter-individual variation in clinical effects following sodium oxybate administration has been reported. The use of DBS as a sampling technique, which is stated to be easy and convenient, may provide a better insight into GHB concentrations following sodium oxybate intake in a real-life setting.

OBJECTIVE

The aim was twofold: evaluation of the applicability of a recently developed DBS-based gas chromatography-mass spectrometry (GC-MS) method, and of the feasibility of the sampling technique in an ambulant setting.

METHODS

Seven narcoleptic patients being treated with sodium oxybate at the Department for Respiratory Diseases of Ghent University Hospital were asked to collect DBS approximately 20 min after the first sodium oxybate (Xyrem(®); UCB Pharma Ltd, Brussels, Belgium) intake on a maximum of 7 consecutive days. Using an automatic lancet, patients pricked their fingertip and, after wiping off the first drop of blood, subsequent drops were collected on a DBS card. The DBS cards were sent to the laboratory by regular mail and, before analysis, were visually inspected to record DBS quality (large enough, symmetrically spread on the filter paper with even colouration on both sides of the filter paper).

RESULTS

Of the seven patients, three patients succeeded to collect five series of DBS, one patient decided to cease participation because of nausea, one was lost during follow-up and two patients started falling asleep almost immediately after the intake of sodium oxybate. Analysing the DBS in duplicate resulted in acceptable within-DBS card precision. DBS with acceptable quality were obtained by patients without supervision.

CONCLUSION

Our results demonstrate the acceptable precision of the complete procedure, from sampling at home to quantitative analysis in the laboratory. Given the intra- and inter-individual variability in clinical effects seen with sodium oxybate, the easy adaptation of DBS sampling opens the possibility of following up GHB concentrations in patients in real-life settings in future studies.

The use of sodium oxybate to treat narcolepsy

Narcolepsy is a life-long neurodegenerative disorder that causes considerable impairment to quality of life. Until the 1970s, the treatment for one of the main symptoms, excessive daytime sleepiness, was restricted to stimulants, whereas the second core symptom, cataplexy, was treated with antidepressants, and the resultant fragmented night-time sleep with hypnotics. Sodium oxybate (Xyrem(®), UCB Pharma, Brussels, Belgium) is an efficacious drug for all three symptoms which improves the quality of life of narcoleptic patients. Owing to its metabolic pathway, there is very little pharmacokinetic interaction with other drugs. In combination with modafinil, some of its therapeutic benefits are enhanced. Adverse events and side effects are moderate when taken according to indication and as recommended. Essential limitations have to be considered before starting the treatment (sleep-related breathing disorders, alcohol intake, hypnotic and sedative comedication, and epilepsy). This article gives an overview of sodium oxybate, which has been US FDA approved for the treatment of cataplexy and excessive daytime sleepiness in patients with narcolepsy, and EMA approved for the treatment of narcolepsy-cataplexy.

Metabolism of γ-hydroxybutyrate in perfused rat livers

GHB (γ-hydroxybutyrate) is both a neurotransmitter and a drug of abuse (date-rape drug). We investigated the catabolism of this compound in perfused rat livers. Using a combination of metabolomics and mass isotopomer analysis, we showed that GHB is metabolized by multiple processes, in addition to its previously reported metabolism in the citric acid cycle via oxidation to succinate. A substrate cycle operates between GHB and γ-aminobutyrate via succinic semialdehyde. Also, GHB undergoes (i) β-oxidation to glycolyl-CoA+acetyl-CoA, (ii) two parallel processes which remove C-1 or C-4 of GHB and form 3-hydroxypropionate from C-2+C-3+C-4 or from C-1+C-2+C-3 of GHB, and (iii) degradation to acetyl-CoA via 4-phosphobutyryl-CoA. The present study illustrates the potential of the combination of metabolomics and mass isotopomer analysis for pathway discovery.

Sodium oxybate therapy provides multidimensional improvement in fibromyalgia: results of an international phase 3 trial

BACKGROUND

Fibromyalgia is characterised by chronic musculoskeletal pain and multiple symptoms including fatigue, multidimensional function impairment, sleep disturbance and tenderness. Along with pain and fatigue, non-restorative sleep is a core symptom of fibromyalgia. Sodium oxybate (SXB) is thought to reduce non-restorative sleep abnormalities. This study evaluated effects of SXB on fibromyalgia-related pain and other symptoms.

METHODS

573 patients with fibromyalgia according to 1990 American College of Rheumatology criteria were enrolled at 108 centres in eight countries. Subjects were randomly assigned to placebo, SXB 4.5 g/night or SXB 6 g/night. The primary efficacy endpoint was the proportion of subjects with ≥30% reduction in pain visual analogue scale from baseline to treatment end. Other efficacy assessments included function, sleep quality, effect of sleep on function, fatigue, tenderness, health-related quality of life and subject's impression of change in overall wellbeing.

RESULTS

Significant improvements in pain, sleep and other symptoms associated with fibromyalgia were seen in SXB treated subjects compared with placebo. The proportion of subjects with ≥30% pain reduction was 42.0% for SXB4.5 g/night (p=0.002) and 51.4% for SXB6 g/night (p<0.001) versus 26.8% for placebo. Quality of sleep (Jenkins sleep scale) improved by 20% for SXB4.5 g/night (p≤0.001) and 25% for SXB6 g/night (p≤0.001) versus 0.5% for placebo. Adverse events with an incidence ≥5% and twice placebo were nausea, dizziness, vomiting, insomnia, anxiety, somnolence, fatigue, muscle spasms and peripheral oedema.

CONCLUSION

These results, combined with findings from previous phase 2 and 3 studies, provide supportive evidence that SXB therapy affords important benefits across multiple symptoms in subjects with fibromyalgia.

Pharmacological management of binge eating disorder: current and emerging treatment options

Growing evidence suggests that pharmacotherapy may be beneficial for some patients with binge eating disorder (BED), an eating disorder characterized by repetitive episodes of uncontrollable consumption of abnormally large amounts of food without inappropriate weight loss behaviors. In this paper, we provide a brief overview of BED and review the rationales and data supporting the effectiveness of specific medications or medication classes in treating patients with BED. We conclude by summarizing these data, discussing the role of pharmacotherapy in the BED treatment armamentarium, and suggesting future areas for research.

Reconsidering GHB: orphan drug or new model antidepressant?

For six decades, the principal mode of action of antidepressant drugs is the inhibition of monoamine re-uptake from the synaptic cleft. Tricyclic antidepressants, selective serotonin re-uptake inhibitors (SSRIs) and the new generation of dual antidepressants all exert their antidepressant effects by this mechanism. In the early days of the monoaminergic era, other efforts have been made to ameliorate the symptoms of depression by pharmacological means. The gamma-aminobutyric acid (GABA) system was and possibly still is one of the main alternative drug targets. Gammahydroxybutyrate (GHB) was developed as an orally active GABA analogue. It was tested in animal models of depression and human studies. The effects on sleep, agitation, anhedonia and depression were promising. However, the rise of benzodiazepines and tricyclic antidepressants brought GHB out of the scope of possible treatment alternatives. GHB is a GABA(B) and GHB receptor agonist with a unique spectrum of behavioural, neuroendocrine and sleep effects, and improves daytime sleepiness in various disorders such as narcolepsy, Parkinson's disease and fibromyalgia. Although it was banned from the US market at the end of the 1990s because of its abuse and overdose potential, it later was approved for the treatment of narcolepsy. New research methods and an extended view on other neurotransmitter systems as possible treatment targets of antidepressant treatment brought GHB back to the scene. This article discusses the unique neurobiological effects of GHB, its misuse potential and possible role as a model substance for the development of novel pharmacological treatment strategies in depressive disorders.

An enzymatic method to determine γ-hydroxybutyric acid in serum and urine

BACKGROUND

Gamma-hydroxybutyric acid (GHB) has become one of the most dangerous illicit drugs of abuse today. It is used as a recreational and date rape drug because of its depressant effect on the central nervous system, which may cause euphoria, amnesia, respiratory arrest, and coma. There is an urgent need for a simple, easy-to-use assay for GHB determination in urine and blood. In this article, a rapid enzymatic assay adapted to clinical chemistry analyzers for the detection of GHB is presented.

METHODS

The described GHB enzymatic assay is based on a recombinant GHB dehydrogenase. The full validation of the assay was performed on a Konelab 30 analyzer (Thermo Fisher Scientific).

RESULTS

The analytical sensitivity was <1.5 mg/L, whereas the functional sensitivity was 4.5 mg/L in serum and 2.8 mg/L in urine. The total imprecision coefficient of variation (CV) was <9.8% in serum and <7.9% in urine. The within-run imprecision showed a CV of <3.8% in serum and <4.6% in urine. The assay was linear within the range 5-250 mg/L. Mean recoveries were 109% in serum and 105% in urine. No cross-reactivity was observed for tested GHB analogues and precursors. Comparison of GHB-positive samples showed an excellent correlation with ion chromatography, gas chromatography-mass spectrometry, and liquid chromatography associated to tandem mass spectrometry. Except for ethanol, no substantial interference from serum constituents and some drugs was observed.

CONCLUSIONS

This automated GHB assay is fully quantitative and allows the accurate measurement of GHB in serum and urine. It can be used as a rapid screening assay for the determination of GHB in intoxicated or overdosed patients.

Multidisciplinary approach to fibromyalgia: what is the teaching?

Fibromyalgia (FM) is a rheumatic disease that is characterised by chronic musculoskeletal pain, stiffness, fatigue, sleep and mood disorder. FM patients demonstrate dysregulation of pain neurotransmitter function and experience a neurohormone-mediated association with sleep irregularities. There are currently no instrumental tests or specific diagnostic markers for FM, and many of the existing indicators are only significant for research purposes. Anti-depressants, non-steroidal anti-inflammatory drugs (NSAIDS), opioids, sedatives, muscle relaxants and antiepileptics have all been used to treat FM with varying results. It has been shown that interdisciplinary treatment programmes lead to greater improvements in subjective pain and function than monotherapies. Physical exercise and multimodal cognitive behavioural therapy are the most widely accepted and beneficial forms of non-pharmacological therapy.