The nightly administration of sodium oxybate results in significant reduction in the nocturnal sleep disruption of patients with narcolepsy

REM sleep in narcolepsy

Narcolepsy is mainly associated with excessive daytime sleepiness, but the characteristic feature is abnormal rapid eye movement (REM) sleep phenomena. REM sleep disturbances can manifest as cataplexy (in narcolepsy type 1), sleep paralysis, sleep-related hallucinations, REM sleep behavior disorder, abnormal dreams, polysomnographic evidence of REM sleep disruption with sleep-onset REM periods, and fragmented REM sleep. Characterization of REM sleep and related symptoms facilitates the differentiation of narcolepsy from other central hypersomnolence disorders and aids in distinguishing between narcolepsy types 1 and 2. A circuit comprising regions within the brainstem, forebrain, and hypothalamus is involved in generating and regulating REM sleep, which is influenced by changes in monoamines, acetylcholine, and neuropeptides. REM sleep is associated with brainstem functions, including autonomic control, and REM sleep disturbances may be associated with increased cardiovascular risk. Medications used to treat narcolepsy (and REM-related symptoms of narcolepsy) include stimulants/wake-promoting agents, pitolisant, oxybates, and antidepressants; hypocretin agonists are a potential new class of therapeutics. The role of REM sleep disturbances in narcolepsy remains an area of active research in pathophysiology, symptom management, and treatment. This review summarizes the current understanding of the role of REM sleep and its dysfunction in narcolepsy.

Efficacy of once-nightly sodium oxybate (FT218) on daytime symptoms in individuals with narcolepsy with or without concomitant alerting agent use: A post hoc analysis from the phase 3 REST-ON trial

OBJECTIVE/BACKGROUND

Extended-release, once-nightly sodium oxybate (ON-SXB) significantly improved narcolepsy symptoms in participants in the phase 3, randomized, double-blind, placebo-controlled REST-ON trial. This post hoc analysis of REST-ON data evaluated ON-SXB efficacy in participants with or without concomitant alerting agent use.

PATIENTS/METHODS

Participants with narcolepsy aged >16 years were randomized 1:1 to ON-SXB (week 1: 4.5 g, weeks 2-3: 6 g, weeks 4-8: 7.5 g, weeks 9-13: 9 g) or placebo. Primary endpoints in this post hoc analysis included change from baseline in mean sleep latency on the Maintenance of Wakefulness Test (MWT), Clinical Global Impression-Improvement (CGI-I) rating, and number of weekly cataplexy episodes. The secondary endpoints were change from baseline in the Epworth Sleepiness Scale (ESS) score and in objective and subjective disrupted nighttime sleep parameters. Post hoc analyses assessed participants with and without alerting agent use across 6-, 7.5-, and 9-g doses.

RESULTS

In the modified intent-to-treat population, 119 (63 %) were (ON-SXB, n = 66; placebo, n = 53) and 71 (37 %) were not (ON-SXB, n = 31; placebo, n = 40) taking alerting agents. Regardless of alerting agent use, treatment with ON-SXB resulted in significant improvements vs placebo (all doses, P < 0.05) for MWT, CGI-I, and number of weekly cataplexy episodes. Significant improvements in ESS (all doses, P < 0.05) with ON-SXB vs placebo were observed in the alerting agent use cohort. Directional improvements in ESS were reported with all doses in the no alerting agent use group.

CONCLUSIONS

Regardless of concomitant alerting agent use, ON-SXB improved daytime and nighttime narcolepsy symptoms vs placebo.

Accidental calcium, magnesium, potassium and sodium oxybates (Xywave) overdose: mistiming of a single night's narcolepsy medication leading to respiratory failure requiring mechanical ventilation

While typically thought of as an illicit substance, oxybate salts or gamma-hydroxybutyrate (GHB) has more recently been prescribed to treat narcolepsy by enhancing night-time sleep resulting in decreased daytime drowsiness. This case involves a college-aged female with prescribed GHB for narcolepsy who took her second nightly dose too early. This resulted in mental depression, respiratory failure, intubation and mechanical ventilation. The patient was successfully extubated in the intensive care unit several hours later with no residual morbidity. We were unable to identify any prior reports of mixed-salt oxybate toxicity following mistimed drug administration. This case should serve as a warning to emergency physicians to be on the lookout for GHB as part of the differential diagnosis for patients with narcolepsy presenting with altered mental status. It should also serve as a warning to patients and prescribers that this medication can have outcomes that require immediate medical intervention.

Effects of oxybate dose and regimen on disrupted nighttime sleep and sleep architecture

Many components of sleep are disrupted in patients with narcolepsy, including sleep quality, sleep architecture, and sleep stability (ie, frequent awakenings/arousals and frequent shifts from deeper to lighter stages of sleep). Sodium oxybate, dosed twice nightly, has historically been used to improve sleep, and subsequent daytime symptoms, in patients with narcolepsy. Recently, new formulations have been developed to address the high sodium content and twice-nightly dosing regimen of sodium oxybate: low-sodium oxybate and once-nightly sodium oxybate. To date, no head-to-head trials have been conducted to compare the effects of each oxybate product. This review aims to give an overview of the existing scientific literature regarding the impact of oxybate dose and regimen on sleep architecture and disrupted nighttime sleep in patients with narcolepsy. Evidence from 5 key clinical trials, as well as supporting evidence from additional studies, suggests that sodium oxybate, dosed once- and twice-nightly, is effective in improving sleep, measures of sleep architecture, and disrupted nighttime sleep in patients with narcolepsy. Direct comparison of available efficacy and safety data between oxybate products is complicated by differences in trial designs, outcomes assessed, and statistical analyses; future head-to-head trials are needed to better understand the advantage and disadvantages of each agent.

Implications of Oxybate Dosing Regimen for Sleep, Sleep Architecture, and Disrupted Nighttime Sleep in Patients with Narcolepsy: A Commentary

Narcolepsy is associated with disrupted nighttime sleep (DNS). Sodium oxybate (SXB; Xyrem®), administered twice nightly, is indicated for the treatment of cataplexy and excessive daytime sleepiness in patients 7 years or older with narcolepsy. Recently, low-sodium oxybate (LXB, Xywav®; for people 7 years of age and older), which contains 92% less sodium than SXB and is dosed twice nightly, and sodium oxybate for extended release (SXB-ER; Lumryz™; for adults), which contains equal sodium to SXB and is dosed once nightly, have also been approved to treat cataplexy or excessive daytime sleepiness in narcolepsy. This paper reviews the evidence regarding the overall impact of oxybate administration, and impact of different oxybate dosing regimens (once nightly, SXB-ER; twice nightly, SXB), on DNS in narcolepsy utilizing polysomnographic data from five clinical trials (three assessing SXB in adults [referred to here as SXB trials 1, 2, and 3], one assessing SXB in children [referred to as the pediatric SXB trial], and one assessing SXB-ER in adults [REST-ON]). Both once-nightly and twice-nightly oxybate regimens similarly improved symptoms of DNS. Regardless of dosing regimen, people with narcolepsy treated with oxybate experience roughly 42-53 arousals and 9-38 awakenings each night, with one of these awakenings on twice-nightly oxybate being due to the second dosing requirement in studies of SXB. Additionally, for SXB, but not SXB-ER, polysomnographic data has been analyzed by half of the night, demonstrating a greater positive impact on sleep architecture in the second half of the night, which might be related to its nonlinear pharmacokinetic profile. We conclude that while once-nightly and twice-nightly oxybate dosing regimens differ in their pharmacokinetic profiles, both improve DNS in patients with narcolepsy to a similar degree.

Long-Term Treatment of Narcolepsy and Idiopathic Hypersomnia with Low-Sodium Oxybate

Narcolepsy and idiopathic hypersomnia are chronic conditions that negatively affect alertness, mental and physical energy, functioning, and quality of life (QoL). Calcium, magnesium, potassium, and sodium oxybates (low-sodium oxybate; LXB) is an oxybate formulation with 92% less sodium than sodium oxybate (SXB; a treatment for narcolepsy) and the same active moiety. LXB is approved in the US for treatment of cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age or older with narcolepsy, and idiopathic hypersomnia in adults. In Phase 3 clinical trials, LXB exhibited a safety profile consistent with that of SXB in narcolepsy. Besides continued efficacy in treating symptoms, potential benefits of long-term LXB treatment include flexible optimization of dosing and regimen, improvement of QoL and functioning, weight loss, and (relative to SXB in narcolepsy) health benefits of reduced sodium content. Dosing of LXB is twice nightly (for narcolepsy) or once or twice nightly (for idiopathic hypersomnia) based on patient characteristics and response, and individualized titration can be leveraged over the long term as a patient's life circumstances change. Patients with narcolepsy transitioning from SXB initiate LXB at the same dose, and most patients require no further changes to achieve similar efficacy and tolerability. Improvements in functioning and QoL with LXB treatment could have cascading positive effects in multiple domains, particularly in younger patients. In clinical trials, LXB was associated with weight loss in both narcolepsy (in which obesity is a well-established comorbidity) and idiopathic hypersomnia, only occasionally leading participants to be underweight. As both narcolepsy and idiopathic hypersomnia are associated with increased risk of cardiometabolic and cardiovascular comorbidities, limiting medication-related sodium intake with LXB may have significant health benefits, although this has not yet been verified prospectively due to the prolonged follow-up required. LXB is a promising long-term treatment for narcolepsy and idiopathic hypersomnia.

A multicenter, double-blind, placebo-controlled, randomized, Phase 1b crossover trial comparing two doses of ulotaront with placebo in the treatment of narcolepsy-cataplexy

BACKGROUND

Ulotaront (SEP-363856) is a novel agonist at trace amine-associated receptor 1 and serotonin 5-HT_1A receptors in clinical development for the treatment of schizophrenia. Previous studies demonstrated ulotaront suppresses rapid eye movement (REM) sleep in both rodents and healthy volunteers. We assessed acute and sustained treatments of ulotaront on REM sleep and symptoms of cataplexy and alertness in subjects with narcolepsy-cataplexy.

METHODS

In a multicenter, double-blind, placebo-controlled, randomized, 3-way crossover study, ulotaront was evaluated in 16 adults with narcolepsy-cataplexy. Two oral doses of ulotaront (25 mg and 50 mg) were administered daily for 2 weeks and compared with matching placebo (6-treatment sequence, 3-period, 3-treatment).

RESULTS

Acute treatment with both 25 mg and 50 mg of ulotaront reduced minutes spent in nighttime REM compared to placebo. A sustained 2-week administration of both doses of ulotaront reduced the mean number of short-onset REM periods (SOREMPs) during daytime multiple sleep latency test (MSLT) compared to placebo. Although cataplexy events decreased from the overall mean baseline during the 2-week treatment period, neither dose of ulotaront statistically separated from placebo (p = 0.76, 25 mg; p = 0.82, 50 mg), and no significant improvement in patient and clinician measures of sleepiness from baseline to end of the 2-week treatment period occurred in any treatment group.

CONCLUSIONS

Acute and sustained treatment with ulotaront reduced nighttime REM duration and daytime SOREMPs, respectively. The effect of ulotaront on suppression of REM did not demonstrate a statistical or clinically meaningful effect in narcolepsy-cataplexy.

REGISTRATION

ClinicalTrials.gov identifier: NCT05015673.

Disrupted nighttime sleep and sleep instability in narcolepsy

STUDY OBJECTIVES

This review aimed to summarize current knowledge about disrupted nighttime sleep (DNS) and sleep instability in narcolepsy, including self-reported and objective assessments, potential causes of sleep instability, health consequences and functional burden, and management.

METHODS

One hundred two peer-reviewed publications from a PubMed search were included.

RESULTS

DNS is a key symptom of narcolepsy but has received less attention than excessive daytime sleepiness and cataplexy. There has been a lack of clarity regarding the definition of DNS, as many sleep-related symptoms and conditions disrupt sleep quality in narcolepsy (eg, hallucinations, sleep paralysis, rapid eye movement sleep behavior disorder, nightmares, restless legs syndrome/periodic leg movements, nocturnal eating, sleep apnea, depression, anxiety). In addition, the intrinsic sleep instability of narcolepsy results in frequent spontaneous wakings and sleep stage transitions, contributing to DNS. Sleep instability likely emerges in the setting of orexin insufficiency/deficiency, but its exact pathophysiology remains unknown. DNS impairs quality of life among people with narcolepsy, and more research is needed to determine its contributions to cardiovascular risk. Multimodal treatment is appropriate for DNS management, including behavioral therapies, counseling on sleep hygiene, and/or medication. There is strong evidence showing improvement in self-reported sleep quality and objective sleep stability measures with sodium oxybate, but rigorous clinical trials with other pharmacotherapies are needed. Treatment may be complicated by comorbidities, concomitant medications, and mood disorders.

CONCLUSIONS

DNS is a common symptom of narcolepsy deserving consideration in clinical care and future research.

CITATION

Maski K, Mignot E, Plazzi G, Dauvilliers Y. Disrupted nighttime sleep and sleep instability in narcolepsy. J Clin Sleep Med. 2022;18(1):289-304.

European guideline and expert statements on the management of narcolepsy in adults and children

BACKGROUND AND PURPOSE

Narcolepsy is an uncommon hypothalamic disorder of presumed autoimmune origin that usually requires lifelong treatment. This paper aims to provide evidence-based guidelines for the management of narcolepsy in both adults and children.

METHODS

The European Academy of Neurology (EAN), European Sleep Research Society (ESRS), and European Narcolepsy Network (EU-NN) nominated a task force of 18 narcolepsy specialists. According to the EAN recommendations, 10 relevant clinical questions were formulated in PICO format. Following a systematic review of the literature (performed in Fall 2018 and updated in July 2020) recommendations were developed according to the GRADE approach.

RESULTS

A total of 10,247 references were evaluated, 308 studies were assessed and 155 finally included. The main recommendations can be summarized as follows: (i) excessive daytime sleepiness (EDS) in adults-scheduled naps, modafinil, pitolisant, sodium oxybate (SXB), solriamfetol (all strong); methylphenidate, amphetamine derivatives (both weak); (ii) cataplexy in adults-SXB, venlafaxine, clomipramine (all strong) and pitolisant (weak); (iii) EDS in children-scheduled naps, SXB (both strong), modafinil, methylphenidate, pitolisant, amphetamine derivatives (all weak); (iv) cataplexy in children-SXB (strong), antidepressants (weak). Treatment choices should be tailored to each patient's symptoms, comorbidities, tolerance and risk of potential drug interactions.

CONCLUSION

The management of narcolepsy involves non-pharmacological and pharmacological approaches with an increasing number of symptomatic treatment options for adults and children that have been studied in some detail.

European guideline and expert statements on the management of narcolepsy in adults and children

BACKGROUND AND AIM

Narcolepsy is an uncommon hypothalamic disorder of presumed autoimmune origin that usually requires lifelong treatment. This paper aims to provide evidence-based guidelines for the management of narcolepsy in both adults and children.

METHODS

The European Academy of Neurology (EAN), European Sleep Research Society (ESRS) and European Narcolepsy Network (EU-NN) nominated a task force of 18 narcolepsy specialists. According to the EAN recommendations, 10 relevant clinical questions were formulated in PICO format. Following a systematic review of the literature (performed in Fall 2018 and updated in July 2020) recommendations were developed according to the GRADE approach.

RESULTS

A total of 10,247 references were evaluated, 308 studies were assessed and 155 finally included. The main recommendations can be summarized as follows: (i) excessive daytime sleepiness in adults-scheduled naps, modafinil, pitolisant, sodium oxybate (SXB), solriamfetol (all strong), methylphenidate, amphetamine derivates (both weak); (ii) cataplexy in adults-SXB, venlafaxine, clomipramine (all strong) and pitolisant (weak); (iii) excessive daytime sleepiness in children-scheduled naps, SXB (both strong), modafinil, methylphenidate, pitolisant, amphetamine derivates (all weak); (iv) cataplexy in children-SXB (strong), antidepressants (weak). Treatment choices should be tailored to each patient's symptoms, comorbidities, tolerance and risk of potential drug interactions.

CONCLUSION

The management of narcolepsy involves non-pharmacological and pharmacological approaches with an increasing number of symptomatic treatment options for adults and children that have been studied in some detail.

Assessing the impact of sodium oxybate treatment on functioning, productivity, and health-related quality of life in patients with narcolepsy: findings from the Nexus Narcolepsy Registry (waves 1-4)

BACKGROUND

The aim of this study was to evaluate the impact of different therapy regimens, including sodium oxybate (SXB)-containing regimens, on patient-reported outcomes (PROs) in people with narcolepsy.

METHODS

Online surveys were used to collect information from persons with narcolepsy in the Nexus Narcolepsy Registry. Surveys contained questionnaires assessing self-reported sleep quality (SQ; via single question), daytime sleepiness and function (Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire), health-related quality of life (HRQoL; 36-Item Short Form Health Survey [SF-36]), work productivity and impairment (Work Productivity and Activity Impairment: Specific Health Problem), and history of injuries or motor vehicle accidents. Treatment with SXB (including monotherapy or combination therapy; SXB group) was compared with non-SXB therapy (No SXB group). The P values presented are nominal, as there are no adjustments for multiplicity.

RESULTS

From June 2015 through December 2017, 983 participants completed 1760 surveys. SQ and daytime functioning scores were better in the SXB group compared with the No SXB group (all P < 0.001). HRQoL scores were better for the SXB group compared with the No SXB group for the SF-36 Physical Component (P = 0.016), Mental Component (P < 0.001), and all 8 subscales. Additionally, PROs were better for the SXB group for presenteeism, overall work and activity impairment, and risk of motor vehicle accidents (all P ≤ 0.001).

CONCLUSION

Based on participants' self-assessments, treatment regimens with SXB were associated with better outcomes than regimens not containing SXB across many PROs, including SQ, HRQoL, work and activities, and risk of traffic accidents. CLINICALTRIALS.

GOV IDENTIFIER

NCT02769780.

Efficacy and safety of calcium, magnesium, potassium, and sodium oxybates (lower-sodium oxybate [LXB]; JZP-258) in a placebo-controlled, double-blind, randomized withdrawal study in adults with narcolepsy with cataplexy

Study Objectives

Evaluate efficacy and safety of lower-sodium oxybate (LXB), a novel oxybate medication with 92% less sodium than sodium oxybate (SXB).

Methods

Adults aged 18–70 years with narcolepsy with cataplexy were eligible. The study included a ≤30-day screening period; a 12-week, open-label, optimized treatment and titration period to transition to LXB from previous medications for the treatment of cataplexy; a 2-week stable-dose period (SDP); a 2-week, double-blind, randomized withdrawal period (DBRWP); and a 2-week safety follow-up. During DBRWP, participants were randomized 1:1 to placebo or to continue LXB treatment.

Results

Efficacy was assessed in 134 participants who received randomized treatment, and safety was assessed in all enrolled participants (N = 201). Statistically significant worsening of symptoms was observed in participants randomized to placebo, with median (first quartile [Q1], third quartile [Q3]) change in weekly number of cataplexy attacks from SDP to DBRWP (primary efficacy endpoint) in the placebo group of 2.35 (0.00, 11.61) versus 0.00 (−0.49, 1.75) in the LXB group (p < 0.0001; mean [standard deviation, SD] change: 11.46 [24.751] vs 0.12 [5.772]), and median (Q1, Q3) change in Epworth Sleepiness Scale score (key secondary efficacy endpoint) of 2.0 (0.0, 5.0) in the placebo group versus 0.0 (−1.0, 1.0) in the LXB group (p < 0.0001; mean [SD] change: 3.0 [4.68] vs 0.0 [2.90]). The most common treatment-emergent adverse events with LXB were headache (20.4%), nausea (12.9%), and dizziness (10.4%).

Conclusions

Efficacy of LXB for the treatment of cataplexy and excessive daytime sleepiness was demonstrated. The safety profile of LXB was consistent with SXB.

Clinical trial registration

NCT03030599.

Direct activation of G-protein-gated inward rectifying K+ channels promotes nonrapid eye movement sleep

STUDY OBJECTIVES

A major challenge in treating insomnia is to find effective medicines with fewer side effects. Activation of G-protein-gated inward rectifying K+ channels (GIRKs) by GABAB agonists baclofen or γ-hydroxybutyric acid (GHB) promotes nonrapid eye movement (NREM) sleep and consolidates sleep. However, baclofen has poor brain penetration, GHB possesses abuse liability, and in rodents both drugs cause spike-wave discharges (SWDs), an absence seizure activity. We tested the hypothesis that direct GIRK activation promotes sleep without inducing SWD using ML297, a potent and selective GIRK activator.

METHODS

Whole-cell patch-clamp recordings from hypocretin/orexin or hippocampal neurons in mouse brain slices were made to study neuronal excitability and synaptic activity; spontaneous activity, locomotion, contextual and tone-conditioned memory, and novel object recognition were assessed. Electroencephalogram/electromyogram (EEG/EMG) recordings were used to study GIRK modulation of sleep.

RESULTS

ML297, like baclofen, caused membrane hyperpolarization, decreased input resistance, and blockade of spontaneous action potentials. Unlike baclofen, ML297 (5-10 µM) did not cause significant depression of postsynaptic excitatory and inhibitory currents (EPSCs-IPSCs), indicating preferential postsynaptic inhibition. ML297 (30 mg/kg, i.p.) inhibited wake activity and locomotion, and preferentially increased NREM sleep without altering EEG delta power, REM sleep, inducing SWDs, or impairing conditioned memory and novel object recognition.

CONCLUSIONS

This study finds that direct activation of neuronal GIRK channels modulates postsynaptic membrane excitability and prolongs NREM sleep without changing sleep intensity, inducing SWDs, or impairing memory in rodents. These results suggest that direct GIRK activation with a selective compound may present an innovative approach for the treatment of chronic insomnia.

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.

Clinical neurophysiology of CNS hypersomnias

Central nervous system hypersomnias (narcolepsy type 1 and type 2, idiopathic hypersomnia, and Kleine-Levin syndrome) are orphan sleep disorders in which the predominant symptom is excessive daytime sleepiness. The evaluation of sleepiness requires rigorous clinical and neurophysiologic approaches that may include the Epworth Sleepiness Scale, multiple sleep latency tests, and the maintenance of wakefulness test. However, to date, no gold standard measurement of excessive sleepiness exists, and there are no quantifiable biologic markers. The main pathophysiologic feature of central hypersomnias is thought to reflect a deficiency of arousal systems, rather than an overactivity of sleep systems or an imbalance between those systems. Impaired neurotransmission of hypocretin/orexin (neuropeptides of the lateral hypothalamus) is involved in the neurobiology of narcolepsy with cataplexy (NT1). NT1 is a well-characterized disorder, due to the destruction of hypocretin/orexin neurons by a probable autoimmune process. The biologic hallmarks of the other central hypersomnias remain unknown, and neurophysiologic biomarkers are still of major importance for the diagnosis and characterization of those disorders.

Gamma-hydroxybutyrate (GHB) for narcolepsy in adults: an updated systematic review and meta-analysis

BACKGROUND

Narcolepsy is a chronic and debilitating sleep disorder characterized by cataplexy and excessive daytime sleeping. Gamma-hydroxybutyrate (GHB) has been widely used to treat narcolepsy, and new findings have been published in recent years.

OBJECTIVE

A meta-analysis was conducted to assess the efficacy and tolerability of GHB treatment in adults with narcolepsy.

METHODS

A systematic search of PubMed, Cochrane, Embase, Web of Science, and clinical-trials.gov from inception to June 2018 was performed. Change in daily diaries and polysomnographic data of narcoleptic patients were defined as the efficacy outcomes. The tolerability and acceptability outcomes were the rates of adverse events and dropping out for adverse effects or other reasons.

RESULTS

Fifteen randomized controlled trials involving 2104 participants were identified. GHB was found to improve cataplexy attacks (P = 0.001), subjective daytime sleepiness (P < 0.0001), daytime sleep latency (P < 0.0001), inadvertent naps/sleep attacks (P < 0.00001), effective rates (Clinical Global Impression of change) (P < 0.00001), hypnagogic hallucinations (P = 0.004), sleep paralysis (P = 0.004), stage 1 sleep (P = 0.04), slow wave sleep (P = 0.003), REM sleep (P = 0.0006), sleep shifts (P = 0.005), nocturnal awakenings (P = 0.004), quality of nocturnal sleep (P < 0.00001), chin muscle activity, and quality of life, but had no effect on stage 2 sleep (P = 0.88). GHB was less well tolerated than placebo because of side effects that occurred in a dose-dependent fashion (RR = 6.08; 95% CI = 2.18 to 16.97; P = 0.0006).

CONCLUSIONS

GHB was effective in improving narcolepsy-cataplexy and related symptoms in adults but was less well tolerated than placebo because of dose-dependent side effects.

Night Stepping: Fitbit Cracks the Case

ABSTRACT

The most common sleep disorders that can result in injurious or violent behaviors include REM sleep behavioral disorder, sleepwalking, comorbid parasomnias, sleep-related dissociative disorder, and obstructive sleep apnea. Video polysomnography is usually indicated to evaluate recurring sleep-related injury in adults. Only one-third of patients with complex paroxysmal nocturnal events will have one of their habitual events on a single night of in-laboratory video polysomnography, most often those who have prominent, high-frequency motor features. We report evidence of sleep walking induced by sodium oxybate identified by steps recorded on a consumer wearable device coinciding with clinical history and evidence of injury.

Monitoring of altered amino acid metabolic pattern in rat urine following intraperitoneal injection with γ-hydroxybutyric acid

INTRODUCTION

γ-Hydroxybutyric acid is a well-known prescription medicine that is used for the clinical treatment of alcohol dependence and narcolepsy. However, the biochemical mechanism underlying γ-hydroxybutyric acid intoxication remains unclear, and metabolomic amino acid profiling and pattern analyses have not been attempted following treatment with γ-hydroxybutyric acid.

OBJECTIVES

We carried out urinary amino acid profiling and pattern analyses in rats to determine the biochemical events associated with altered amino acid metabolism and biomarker detection of intoxication following treatment with γ-hydroxybutyric acid.

METHODS

Metabolic profiling analysis of amino acids in rat urine samples was performed as ethoxycarbonyl/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry following intraperitoneal administration of γ-hydroxybutyric acid once per day for 1 and 10 consecutive days.

RESULTS

A total of 28 amino acids were positively identified in urine samples from the control, single and multiple groups treated with γ-hydroxybutyric acid. Their levels from the single and multiple treated groups were normalized to the corresponding mean control values. The star graphic pattern of the amino acids was characteristic and readily distinguishable for each group owing to its distorted nonacosagonal shape. In the principle component analysis, we monitored phenylalanine, glutamic acid, aspartic acid, asparagine, and methionine as contributing factors that discriminated the three groups.

CONCLUSION

The present metabolomic study may explain the altered metabolism of amino acids following administration, and intoxication with γ-hydroxybutyric acid.

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.

Safety and efficacy of long-term use of sodium oxybate for narcolepsy with cataplexy in routine clinical practice

Background

Sodium oxybate is licensed in Europe for the treatment of narcolepsy with cataplexy in adults. The aim of this study was to assess the efficacy and safety of sodium oxybate in clinical practice in patients with narcolepsy and cataplexy refractory to other treatments.

Materials and methods

This was a retrospective single centre study including patients with severe narcolepsy with cataplexy refractory to other treatments, who were initiated on sodium oxybate between 2009 and 2015. Patients were allowed to be on other stimulants or/and anti-cataplectic agents. Epworth sleepiness scale (ESS) and weekly cataplexy events were recorded. Side effects (SEs) were recorded at every follow-up visit.

Results

90 patients were prescribed sodium oxybate, with a total of 3116 patient-months of drug exposure. ESS and weekly cataplexy events were significantly reduced by sodium oxybate for all patients (ΔESS = 4.3 ± 4.4 and Δcataplexy = 21.8 ± 18.5 events/week; p < 0.0001, respectively). The required maintenance dose could not be predicted based upon gender, body mass index, or clinical factors. 60% of patients were able to reduce or come off other medications. Half of the patients experienced at least one SE, and 26.6% had to stop treatment due to limiting SEs. Nausea, mood swings and enuresis were the most commonly reported SEs. SEs that led to drug discontinuation, particularly psychosis, were associated with increasing age and were observed early after the initiation of the drug.

Conclusions

Sodium oxybate provides a good clinical efficacy and acceptable safety profile in routine clinical practice for the treatment of patients suffering from narcolepsy with cataplexy. A quarter of patients experience SEs requiring withdrawal of the drug with older patients being more vulnerable to the more serious SEs.

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Sodium oxybate improves alertness in refractory to treatment patients with narcolepsy with cataplexy.

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Sodium oxybate improves cataplexy in refractory to treatment patients with narcolepsy with cataplexy.

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1/4 of the patients had to withdraw from the drug due to side effects.

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In half of the patients sodium oxybate led to reduction of other drug dosages and in 10% to discontinuation.

Narcolepsy

Narcolepsy is a chronic sleep disorder that has a typical onset in adolescence and is characterized by excessive daytime sleepiness, which can have severe consequences for the patient. Problems faced by patients with narcolepsy include social stigma associated with this disease, difficulties in obtaining an education and keeping a job, a reduced quality of life and socioeconomic consequences. Two subtypes of narcolepsy have been described (narcolepsy type 1 and narcolepsy type 2), both of which have similar clinical profiles, except for the presence of cataplexy, which occurs only in patients with narcolepsy type 1. The pathogenesis of narcolepsy type 1 is hypothesized to be the autoimmune destruction of the hypocretin-producing neurons in the hypothalamus; this hypothesis is supported by immune-related genetic and environmental factors associated with the disease. However, direct evidence in support of the autoimmune hypothesis is currently unavailable. Diagnosis of narcolepsy encompasses clinical, electrophysiological and biological evaluations, but simpler and faster procedures are needed. Several medications are available for the symptomatic treatment of narcolepsy, all of which have quite good efficacy and safety profiles. However, to date, no treatment hinders or slows disease development. Improved diagnostic tools and increased understanding of the pathogenesis of narcolepsy type 1 are needed and might lead to therapeutic or even preventative interventions.

Disrupted nighttime sleep in narcolepsy

STUDY OBJECTIVES

Characterize disrupted nighttime sleep (DNS) in narcolepsy, an important symptom of narcolepsy.

METHODS

A panel of international narcolepsy experts was convened in 2011 to build a consensus characterization of DNS in patients with narcolepsy. A literature search of the Medline (1965 to date), Medline In-Process (latest weeks), Embase (1974 to date), Embase Alert (latest 8 weeks), and Biosis (1965 to date) databases was conducted using the following search terms: narcolepsy and disrupted nighttime sleep, disturbed nighttime sleep, fragmented sleep, consolidated sleep, sleep disruption, and narcolepsy questionnaire. The purpose of the literature search was to identify publications characterizing the nighttime sleep of patients with narcolepsy. The panel reviewed the literature. Nocturnal sleep can also be disturbed by REM sleep abnormalities such as vivid dreaming and REM sleep behavior disorder; however, these were not reviewed in the current paper, as we were evaluating for idiopathic sleep disturbances.

RESULTS

The literature reviewed provide a consistent characterization of nighttime sleep in patients with narcolepsy as fragmented, with reports of frequent, brief nightly awakenings with difficulties returning to sleep and associated reports of poor sleep quality. Polysomnographic studies consistently report frequent awakenings/arousals after sleep onset, more stage 1 (S1) sleep, and more frequent shifts to S1 sleep or wake from deeper stages of sleep. The consensus of the International Experts' Panel on Narcolepsy was that DNS can be distressing for patients with narcolepsy and that treatment of DNS warrants consideration.

CONCLUSIONS

Clinicians involved in the management of patients with narcolepsy should investigate patients' quality of nighttime sleep, give weight and consideration to patient reports of nighttime sleep experience, and consider DNS a target for treatment.

Sodium oxybate for narcolepsy with cataplexy: systematic review and meta-analysis

STUDY OBJECTIVES

To assess the efficacy and safety of sodium oxybate (SXB) in narcolepsy-cataplexy patients.

DESIGN

Systematic review and meta-analysis.

PATIENTS

Adults with narcolepsy-cataplexy.

INTERVENTIONS

SXB.

MEASUREMENTS AND RESULTS

Electronic databases (e.g., MEDLINE) and references of included studies were searched to identify randomized controlled trials (RCTs) assessing the efficacy and safety of SXB for patients with narcolepsy-cataplexy. Risk of bias was appraised using the Cochrane risk of bias tool. Meta-analysis was conducted in Review Manager Version 5. Six RCTs and 5 companion reports were included after screening 14 full-text articles and 483 citations. All were private-industry funded. SXB (usually 9 g/night) was superior to placebo for reducing mean weekly cataplexy attacks (n = 2 RCTs, mean difference [MD]: -8.5, 95% CI: -15.3, -1.6), increasing maintenance wakefulness test (MWT) (n = 2, MD: 5.18, 95% CI: 2.59-7.78), reducing sleep attacks (n = 2, MD: -9.65, 95% CI: -17.72, -1.59), and increasing Clinical Global Impression scores (n = 3, relative risk, RR: 2.42, 95% CI: 1.77-3.32). SXB did not significantly increase REM sleep versus placebo (n = 2, MD: -0.49, 95% CI: -3.90, 2.92). Patients receiving SXB had statistically more adverse events versus placebo, including nausea (n = 3, relative risk [RR]: 7.74, 95% CI: 3.2, 19.2), vomiting (n = 2, RR: 11.8, 95% CI: 1.6, 89.4), and dizziness (n = 3, RR: 4.3, 95% CI: 1.1, 16.4). Enuresis was not significantly different from placebo (n = 2, RR: 2.6, 95% CI: 0.8, 9.8). All meta-analyses had minimal statistical heterogeneity (p-value > 0.1).

CONCLUSION

Narcolepsy patients on SXB have significant reductions in cataplexy and daytime sleepiness. SXB is well tolerated in patients with narcolepsy, and most adverse events were mild to moderate in severity.

Possible long-term effects of γ-hydroxybutyric acid (GHB) due to neurotoxicity and overdose

In several countries, including the Netherlands, the use of GHB seems to be rising. GHB is regarded by recreational users as an innocent drug without any side effects. Recently, the number of patients in treatment due to GHB addiction sharply increased. In addition, various studies report incidents following risky GHB use or GHB overdosing. Other sedative drugs, like ketamine and alcohol have been shown to result in unintended neurotoxic harm at the level of memory and cognitive function. As outlined in the present review, GHB and ketamine have a common mode of action, which suggests that GHB may also lead to similar neurotoxicity as ketamine. GHB overdosing, as well as binge drinking (and high ketamine doses), induce profound coma which is probably neurotoxic for the brain especially in the maturing brain of young adults. It is therefore advocated to investigate possible long-term neurotoxic effects in recreational GHB users e.g. by studying the residual effects on cognition and memory.

Modafinil reverses hypoexcitability of the motor cortex in narcoleptic patients: a TMS study

OBJECTIVE

Although many animal and human studies have been performed, the exact mechanisms of action whereby modafinil promotes wakefulness are still not completely understood. We aimed to investigate the functional effects of modafinil on motor cortex excitability in patients with narcolepsy by means of transcranial magnetic stimulation (TMS) techniques.

METHODS

In a double-blind and placebo-controlled design, 24 drug-naive narcoleptic patients with cataplexy and 20 control subjects were administered modafinil or placebo over a period of 4 weeks. TMS was performed twice during the awake state before and at the end of treatment; measures of cortical excitability included central motor conduction time, resting motor threshold, short latency intracortical inhibition (SICI) and intracortical facilitation to paired-TMS. TMS measures were correlated with the conventional neurophysiological method of Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS).

RESULTS

As previously reported, motor threshold and SICI were significantly increased in patients with narcolepsy; modafinil reversed this cortical hypoexcitability, but only SICI differences reached statistical significance. The Spearman rank correlation analysis revealed the highest correlation between SICI and the MSLT; a positive correlation was also found between SICI and the ESS, as well as between RMT and both measures of daytime sleepiness.

CONCLUSIONS

This represents the first report investigating effects of modafinil on cortical excitability in human narcolepsy. Since SICI is thought to be directly related to GABA(A) intracortical inhibitory activity, we demonstrated that the dose of modafinil that induces a satisfactory wakefulness-promoting response in narcoleptic patients also causes decrease in GABAergic transmission.

Differential effects of GABAB receptor subtypes, {gamma}-hydroxybutyric Acid, and Baclofen on EEG activity and sleep regulation

The role of GABA(B) receptors in sleep is still poorly understood. GHB (γ-hydroxybutyric acid) targets these receptors and is the only drug approved to treat the sleep disorder narcolepsy. GABA(B) receptors are obligate dimers comprised of the GABA(B2) subunit and either one of the two GABA(B1) subunit isoforms, GABA(B1a) and GABA(B1b). To better understand the role of GABA(B) receptors in sleep regulation, we performed electroencephalogram (EEG) recordings in mice devoid of functional GABA(B) receptors (1(-/-) and 2(-/-)) or lacking one of the subunit 1 isoforms (1a(-/-) and 1b(-/-)). The distribution of sleep over the day was profoundly altered in 1(-/-) and 2(-/-) mice, suggesting a role for GABA(B) receptors in the circadian organization of sleep. Several other sleep and EEG phenotypes pointed to a more prominent role for GABA(B1a) compared with the GABA(B1b) isoform. Moreover, we found that GABA(B1a) protects against the spontaneous seizure activity observed in 1(-/-) and 2(-/-) mice. We also evaluated the effects of the GHB-prodrug GBL (γ-butyrolactone) and of baclofen (BAC), a high-affinity GABA(B) receptor agonist. Both drugs induced a state distinct from physiological sleep that was not observed in 1(-/-) and 2(-/-) mice. Subsequent sleep was not affected by GBL whereas BAC was followed by a delayed hypersomnia even in 1(-/-) and 2(-/-) mice. The differential effects of GBL and BAC might be attributed to differences in GABA(B)-receptor affinity. These results also indicate that all GBL effects are mediated through GABA(B) receptors, although these receptors do not seem to be involved in mediating the BAC-induced hypersomnia.

Advances in narcolepsy

Narcolepsy with cataplexy is a rare but life-long and challenging disorder. Current insight into the pathophysiology of this condition seems to be autoimmune-mediated postnatal cell death of hypocretin neurons occurring by organ-specific autoimmune targeting with HLA-T-cell receptor interactions. The hypocretin system seems to have an influence on multiple organ systems beyond its wake-promoting mechanisms. The recent availability of cerebrospinal fluid hypocretin-1 analysis has led to definitive diagnostic criteria for narcolepsy with cataplexy. Pharmacologic first-line treatments for excessive daytime sleepiness and cataplexy is sodium oxybate, with modafinil for daytime sleepiness, in adults and children. Other investigative agents and treatment modalities hold promise in future directions for narcolepsy.

Antidepressant drugs for narcolepsy

BACKGROUND

Narcolepsy is a disorder of the central nervous system, the main symptoms of which are excessive daytime sleepiness (EDS) and cataplexy (an abrupt and reversible decrease in or loss of muscle tone, affecting the limbs or trunk or both, elicited by emotional stimuli). Narcolepsy has an adverse impact on people's quality of life. Together with stimulant drugs (used to control EDS), antidepressants are usually recommended to counteract cataplexy. In addition, some antidepressants are also reported to improve EDS.

OBJECTIVES

To evaluate the effects of antidepressant drugs on EDS, cataplexy, quality of life, and their side effects in people with narcolepsy.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2007), MEDLINE (1966 to 2007), EMBASE (1980 to 2007), PsycINFO (1872 to 2007), and CINAHL (1981 to 2007). Bibliographies of identified articles were reviewed to find additional references. Unpublished randomised trials were searched for by consulting governmental and non-governmental clinical trial registers, disease-specific websites, investigators and experts in the field, pharmaceutical companies/manufacturers.

SELECTION CRITERIA

Parallel or cross-over randomised or quasi-randomised controlled trials testing the treatment of narcolepsy with any type of antidepressant drug versus no treatment, placebo, or another antidepressant drug.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

Three cross-over and two parallel trials were included with a total of 246 participants. The methodological quality of all studies was unclear. As the trials tested different comparisons, or had a different design or dealt with different outcome measures, meta-analysis was not performed. In one cross-over trial (10 participants) femoxetine had no significant effect in eliminating or reducing EDS but significantly reduced cataplexy. Mild and transient side effects were reported in the femoxetine treatment period by two participants. In a second cross-over trial (56 participants) viloxazine significantly reduced EDS and cataplexy. In a third cross-over trial the authors inappropriately treated the trial design as a parallel study and no conclusions can be reached in favour of either drug. Two more trials with parallel design tested ritanserin versus placebo without finding differences of effectiveness in reducing EDS or cataplexy.

AUTHORS' CONCLUSIONS

There was no good quality evidence that antidepressants are effective for narcolepsy or improve quality of life. Despite the clinical consensus recommending antidepressants for cataplexy there is scarce evidence that antidepressants have a positive effect on this symptom. There is a clear need for well-designed randomised controlled trials to assess the effect of antidepressants on narcolepsy.