Data-Driven Phenotyping of Central Disorders of Hypersomnolence With Unsupervised Clustering

BACKGROUND AND OBJECTIVES

Recent studies fueled doubts as to whether all currently defined central disorders of hypersomnolence are stable entities, especially narcolepsy type 2 and idiopathic hypersomnia. New reliable biomarkers are needed, and the question arises of whether current diagnostic criteria of hypersomnolence disorders should be reassessed. The main aim of this data-driven observational study was to see whether data-driven algorithms would segregate narcolepsy type 1 and identify more reliable subgrouping of individuals without cataplexy with new clinical biomarkers.

METHODS

We used agglomerative hierarchical clustering, an unsupervised machine learning algorithm, to identify distinct hypersomnolence clusters in the large-scale European Narcolepsy Network database. We included 97 variables, covering all aspects of central hypersomnolence disorders such as symptoms, demographics, objective and subjective sleep measures, and laboratory biomarkers. We specifically focused on subgrouping of patients without cataplexy. The number of clusters was chosen to be the minimal number for which patients without cataplexy were put in distinct groups.

RESULTS

We included 1,078 unmedicated adolescents and adults. Seven clusters were identified, of which 4 clusters included predominantly individuals with cataplexy. The 2 most distinct clusters consisted of 158 and 157 patients, were dominated by those without cataplexy, and among other variables, significantly differed in presence of sleep drunkenness, subjective difficulty awakening, and weekend-week sleep length difference. Patients formally diagnosed as having narcolepsy type 2 and idiopathic hypersomnia were evenly mixed in these 2 clusters.

DISCUSSION

Using a data-driven approach in the largest study on central disorders of hypersomnolence to date, our study identified distinct patient subgroups within the central disorders of hypersomnolence population. Our results contest inclusion of sleep-onset REM periods in diagnostic criteria for people without cataplexy and provide promising new variables for reliable diagnostic categories that better resemble different patient phenotypes. Cluster-guided classification will result in a more solid hypersomnolence classification system that is less vulnerable to instability of single features.

Common Sleep Disorders in Adults: Diagnosis and Management

Sleep disorders are common in the general adult population and are associated with adverse effects such as motor vehicle collisions, decreased quality of life, and increased mortality. Patients with sleep disorders can be categorized into three groups: people with problems falling asleep, people with behavior and movement disturbances during sleep, and people with excessive daytime sleepiness. Insomnia, the most common sleep disorder, is defined by difficulty initiating sleep, maintaining sleep, or both, resulting in daytime consequences. Insomnia is diagnosed by history and is treated with cognitive behavior therapy, with or without medications. Rapid eye movement sleep behavior disorder is characterized by increased muscle tone during rapid eye movement sleep, resulting in patients acting out their dreams with potentially harmful effects. Rapid eye movement sleep behavior disorder is diagnosed by polysomnography and treated with melatonin or clonazepam. Restless legs syndrome is defined by an urge to move the legs that worsens when at rest. Restless legs syndrome is treated with gabapentin or dopamine agonists, depending on the severity. Narcolepsy is characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, and sleep hallucinations. Diagnosis is suggested by the history and can be confirmed with polysomnography and a multiple sleep latency test the following day. Narcolepsy is treated with behavior modifications and medications such as stimulants, selective serotonin reuptake inhibitors, sodium oxybate, and pitolisant. Obstructive sleep apnea may be diagnosed in patients with excessive snoring and witnessed apneas and can be diagnosed using overnight polysomnography. Treatment consists of positive airway pressure therapy while sleeping in conjunction with weight loss.

Effect of FT218, a Once-Nightly Sodium Oxybate Formulation, on Disrupted Nighttime Sleep in Patients with Narcolepsy: Results from the Randomized Phase III REST-ON Trial

BACKGROUND

Sodium oxybate has been recognized as a gold standard for the treatment of disrupted nighttime sleep due to narcolepsy. Its short half-life and immediate-release formulation require patients to awaken 2.5-4 h after their bedtime dose to take a second dose. A novel extended-release, once-nightly sodium oxybate formulation (ON-SXB; FT218) is under US Food and Drug Administration review for the treatment of adults with narcolepsy.

OBJECTIVE

A phase III trial of ON-SXB in individuals with narcolepsy type 1 (NT1) or 2 (NT2) [the REST-ON trial; NCT02720744] has been conducted and the primary results reported elsewhere. Secondary objectives from REST-ON were to assess the efficacy of ON-SXB on disrupted nighttime sleep; the results of this analysis are reported here.

METHODS

In the double-blind, phase III REST-ON trial, patients aged ≥ 16 years were randomly assigned 1:1 to ON-SXB (1 week, 4.5 g; 2 weeks, 6 g; 5 weeks, 7.5 g; 5 weeks, 9 g) or placebo. Secondary endpoints included polysomnographic measures of sleep stage shifts and nocturnal arousals and patient-reported assessments of sleep quality and refreshing nature of sleep at 6, 7.5, and 9 g; post hoc analyses included changes in time spent in each sleep stage, delta power, and assessments in stimulant-use subgroups for prespecified endpoints.

RESULTS

In total, 190 participants (n = 97, ON-SXB; n = 93, placebo) were included in the efficacy analyses. All three ON-SXB doses demonstrated a clinically meaningful, statistically significant decrease vs placebo in the number of transitions to wake/N1 from N1, N2, and rapid eye movement (REM) stages (all doses p < 0.001) and the number of nocturnal arousals (p < 0.05 ON-SXB 6 g; p < 0.001 7.5 and 9 g). Sleep quality and refreshing nature of sleep were significantly improved with all three ON-SXB doses vs placebo (p < 0.001). Post hoc analyses revealed a significant reduction in time spent in N1 (p < 0.05 ON-SXB 6 g; p < 0.001 7.5 and 9 g) and REM (all p < 0.001) and increased time spent in N3 with ON-SXB vs placebo (all p < 0.001), with a significant increase in delta power (p < 0.01 ON-SXB 6 g; p < 0.05 7.5 g; p < 0.001 9 g) and increased REM latency (ON-SXB 7.5 g vs placebo; p < 0.05). Significant improvements in disrupted nighttime sleep were observed regardless of concomitant stimulant use.

CONCLUSIONS

The clinically beneficial, single nighttime dose of ON-SXB significantly improved disrupted nighttime sleep in patients with narcolepsy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT02720744.

Optimal dose determination of enerisant (TS-091) for patients with narcolepsy: two randomized, double-blind, placebo-controlled trials

BACKGROUND

The histamine H3 receptor has emerged as one of the most promising targets of novel pharmacotherapy for narcolepsy. Studies now aim to investigate the optimal dose of enerisant, a novel H3 antagonist/inverse agonist, for the treatment of excessive daytime sleepiness in patients with narcolepsy.

METHODS

We conducted two phase 2, fixed-dose, double-blind, randomized, placebo-controlled trials in patients with narcolepsy. The first phase 2 study (Study 1) was conducted to investigate the efficacy and safety of enerisant at dosages of 25, 50, and 100 mg/day administered for 3 weeks based on the results of a phase 1 study conducted on healthy volunteers. The primary endpoint was mean sleep latency in maintenance of wakefulness test (MWT), and the secondary endpoint was the total score on the Epworth Sleepiness Scale (ESS). The dosages of enerisant in the second phase 2 study (Study 2) were set at 5 and 10 mg/day based on the simulation of receptor occupancy results from positron emission tomography study.

RESULTS

Forty-six and fifty-three patients were randomized in Study 1 and Study 2, respectively. The efficacy of enerisant was partially confirmed in Study 1 with ESS; however, the doses were not tolerated, and there were many withdrawals due to adverse events (mainly insomnia, headache, and nausea). The doses in Study 2 were well tolerated, with a lower incidence of adverse events in Study 2 than in Study 1, although the efficacy could not be confirmed with MWT and ESS in Study 2.

CONCLUSIONS

The optimal dose of enerisant could not be determined in these two studies. Although enerisant has a favorable pharmacokinetic profile, it is thought to have large interindividual variabilities in terms of efficacy and safety, suggesting the necessity of tailored dosage adjustments.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03267303 ; Registered 30 August 2017 (Study 2). Japic identifier: JapicCTI-142529 ; Registered 7 May 2014 (Study 1) and JapicCTI-173689 ; Registered 30 August 2017, https://www.clinicaltrials.jp/cti-user/trial/ShowDirect.jsp?clinicalTrialId=29277 (Study 2).

Incidence and duration of common early-onset adverse events in randomized controlled trials of solriamfetol for treatment of excessive daytime sleepiness in obstructive sleep apnea and narcolepsy

STUDY OBJECTIVES

This post hoc analysis characterized the weekly incidence and overall duration of common early-onset, treatment-emergent adverse events (TEAEs) during solriamfetol treatment.

METHODS

Participants (obstructive sleep apnea [OSA], n = 474; narcolepsy, n = 236) were randomized to 12 weeks of placebo or solriamfetol 37.5 (OSA only), 75, 150, or 300 mg. For common early-onset TEAEs (those occurring in ≥ 5% of participants in any solriamfetol dose group and with a higher incidence than that observed in placebo-treated participants during week 1), the incidence of new occurrence or change in severity over time was calculated for each subsequent study week. Data were analyzed separately for each study and summarized by placebo and combined solriamfetol groups.

RESULTS

Common early-onset TEAEs (at doses ≤ 150 mg; ie, approved doses) included headache (OSA, 5.1%; narcolepsy, 8.5%), nausea (OSA, 2.5%; narcolepsy, 4.2%), decreased appetite (OSA, 4.2%; narcolepsy, 5.9%), as well as anxiety (2.1%), insomnia (1.3%), and feeling jittery (3.0%) in OSA and dry mouth (4.2%) in narcolepsy. Incidence of common early-onset TEAEs was highest at week 1 and decreased over time. In OSA at doses ≤ 150 mg, headache, nausea, and feeling jittery had median durations ≤ 8 days, whereas decreased appetite, anxiety, and insomnia had longer durations. In narcolepsy at doses ≤ 150 mg, headache and nausea had median durations ≤ 8 days, whereas decreased appetite and dry mouth had longer durations. Most TEAEs were mild to moderate in severity.

CONCLUSIONS

Common early-onset TEAEs with solriamfetol are limited in duration, with the majority subsiding during the first week of treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Twelve-week Study of the Safety and Efficacy of JZP-110 in the Treatment of Excessive Sleepiness in Narcolepsy; URL: https://clinicaltrials.gov/ct2/show/NCT02348593; Identifier: NCT02348593; and Name: Twelve-week Study of the Safety and Efficacy of JZP-110 in the Treatment of Excessive Sleepiness in OSA; URL: https://clinicaltrials.gov/ct2/show/NCT02348606; Identifier: NCT02348606.

CITATION

Rosenberg R, Thorpy MJ, Dauvilliers Y, et al. Incidence and duration of common early-onset adverse events in randomized controlled trials of solriamfetol for treatment of excessive daytime sleepiness in obstructive sleep apnea and narcolepsy. J Clin Sleep Med. 2022;18(1):235-244.

Calcium, Magnesium, Potassium and Sodium Oxybates (Xywav®) in Sleep Disorders: A Profile of Its Use

Calcium, magnesium, potassium and sodium oxybates (Xywav^®; hereafter referred to as lower-sodium oxybate), a new oxybate formulation with a greatly reduced sodium burden compared with previously approved sodium oxybate (Xyrem^®), is approved for the treatment of cataplexy and excessive daytime sleepiness (EDS) in adults and children aged ≥ 7 years with narcolepsy, and is the first drug approved for the treatment of idiopathic hypersomnia in adults in the USA. In two pivotal, double-blind, placebo-controlled, phase 3 trials of randomized-withdrawal design, lower-sodium oxybate effectively improved cataplexy and EDS in adults with narcolepsy, and EDS and overall idiopathic hypersomnia symptoms in adults with idiopathic hypersomnia during open-label titration and optimization periods. At the end of the double-blind, randomized withdrawal period, participants randomized to switch to placebo experienced significant worsening in these symptoms compared with those randomized to continue lower-sodium oxybate. Furthermore, worsening in patient- and clinical-rated global scales, as well as measures of health-related quality of life were also seen with placebo versus lower-sodium oxybate. Lower-sodium oxybate is generally well tolerated, with the tolerability profile being largely consistent to that seen with sodium oxybate.

Onset of narcolepsy type 1 in a paraneoplastic encephalitis associated with a thymic seminoma

Narcolepsy type 1 results from probable autoimmune disruption of hypothalamic hypocretinergic neurons. Secondary narcolepsy can occur as a result of other conditions affecting the central nervous system, including limbic paraneoplastic encephalitis. We report the case of a 19-year-old patient presenting with acute-onset diurnal hypersomnolence, hyperphagia, sexual dysfunction, and psychiatric disturbances. Further investigations revealed a limbic paraneoplastic encephalitis associated with mediastinal thymic seminoma. Tumor removal and immunosuppressive treatment resulted in a partial benefit on psychiatric disturbances but did not improve daytime sleepiness. A comprehensive sleep assessment led to the diagnosis of secondary narcolepsy type 1 with reduced cerebrospinal fluid hypocretin-1 levels and revealed the presence of the HLA DQB1*0602 allele, typically associated with idiopathic narcolepsy, for which we hypothesize a possible immunopathogenic role. Sodium oxybate was successfully administered. Narcolepsy is often overlooked in patients with limbic paraneoplastic encephalitis. A prompt assessment and an adequate symptomatic treatment can improve the disease burden.

CITATION

Rossi S, Asioli GM, Rizzo G, et al. Onset of narcolepsy type 1 in a paraneoplastic encephalitis associated with a thymic seminoma. J Clin Sleep Med. 2021;17(12):2557-2560.

Time to Onset of Response to Pitolisant for the Treatment of Excessive Daytime Sleepiness and Cataplexy in Patients With Narcolepsy: An Analysis of Randomized, Placebo-Controlled Trials

BACKGROUND

Pitolisant is approved in the USA and Europe for the treatment of excessive daytime sleepiness or cataplexy in adults with narcolepsy.

OBJECTIVE

Analyses evaluated the time to onset of clinical response during treatment with pitolisant.

METHODS

Data were obtained from two randomized, double-blind, 7-week or 8-week, placebo-controlled studies (HARMONY 1, HARMONY CTP). Study medication was individually titrated to a maximum dose of pitolisant 35.6 mg/day and then remained stable. Efficacy assessments included the Epworth Sleepiness Scale and weekly rate of cataplexy (calculated from patient diaries). Onset of clinical response was defined as the first timepoint at which there was statistical separation between pitolisant and placebo.

RESULTS

The analysis included 61 patients in HARMONY 1 (pitolisant, n = 31; placebo, n = 30) and 105 patients in HARMONY CTP (pitolisant, n = 54; placebo, n = 51). Onset of clinical response began at week 2 (HARMONY 1) or week 3 (HARMONY CTP) for the mean change in Epworth Sleepiness Scale score, and week 2 (HARMONY CTP) or week 5 (HARMONY 1) for the mean change in weekly rate of cataplexy, with further improvements observed in pitolisant-treated patients through the end of treatment. The percentage of treatment responders was significantly greater with pitolisant vs placebo beginning at week 3 for excessive daytime sleepiness (defined as an Epworth Sleepiness Scale score reduction ≥ 3) and week 2 for cataplexy (defined as a ≥ 50% reduction in weekly rate of cataplexy [HARMONY CTP]).

CONCLUSIONS

Onset of clinical response for excessive daytime sleepiness and/or cataplexy was generally observed within the first 2-3 weeks of pitolisant treatment in patients with narcolepsy. CLINICALTRIALS.

GOV IDENTIFIER

NCT01067222 (February 2010), NCT01800045 (February 2013).

Pitolisant, a wake-promoting agent devoid of psychostimulant properties: Preclinical comparison with amphetamine, modafinil, and solriamfetol

Several therapeutic options are currently available to treat excessive daytime sleepiness (EDS) in patients suffering from narcolepsy or obstructive sleep apnea. However, there are no comparisons between the various wake-promoting agents in terms of mechanism of action, efficacy, or safety. The goal of this study was to compare amphetamine, modafinil, solriamfetol, and pitolisant at their known primary pharmacological targets, histamine H3 receptors (H3R), dopamine, norepinephrine, and serotonin transporters, and in various in vivo preclinical models in relation to neurochemistry, locomotion, behavioral sensitization, and food intake. Results confirmed that the primary pharmacological effect of amphetamine, modafinil, and solriamfetol was to increase central dopamine neurotransmission, in part by inhibiting its transporter. Furthermore, solriamfetol increased levels of extracellular dopamine in the nucleus accumbens, and decreased the 3,4-dihydroxyphenyl acetic acid (DOPAC)/DA ratio in the striatum, as reported for modafinil and amphetamine. All these compounds produced hyperlocomotion, behavioral sensitization, and hypophagia, which are common features of psychostimulants and of compounds with abuse potential. In contrast, pitolisant, a selective and potent H3R antagonist/inverse agonist that promotes wakefulness, had no effect on striatal dopamine, locomotion, or food intake. In addition, pitolisant, devoid of behavioral sensitization by itself, attenuated the hyperlocomotion induced by either modafinil or solriamfetol. Therefore, pitolisant presents biochemical, neurochemical, and behavioral profiles different from those of amphetamine and other psychostimulants such as modafinil or solriamfetol. In conclusion, pitolisant is a differentiated therapeutic option, when compared with psychostimulants, for the treatment of EDS, as this agent does not show any amphetamine-like properties within in vivo preclinical models.

Efficacy of pitolisant in patients with high burden of narcolepsy symptoms: pooled analysis of short-term, placebo-controlled studies

STUDY OBJECTIVE

To evaluate the efficacy of pitolisant, a histamine 3 (H₃)-receptor antagonist/inverse agonist, in adult patients with high burden of narcolepsy symptoms.

METHODS

Data were pooled from two randomized, placebo-controlled, 7- or 8-week studies of pitolisant (titrated to a potential maximum dose of 35.6 mg/day) in adults with narcolepsy. Analyses included three independent patient subgroups: Epworth Sleepiness Scale (ESS) baseline score ≥16, Maintenance of Wakefulness Test (MWT) sleep latency ≤8 min, and ≥15 cataplexy attacks per week.

RESULTS

The analysis populations included 118 patients for ESS (pitolisant, n = 60; placebo, n = 58), 105 for MWT (pitolisant, n = 59; placebo, n = 46), and 31 for cataplexy (pitolisant, n = 20; placebo, n = 11). On the ESS, least-squares mean change from baseline was significantly greater for pitolisant (-6.1) compared with placebo (-2.3; P < 0.001). Significantly more pitolisant-treated patients were classified as treatment responders: ESS score reduction ≥3, 69.0% in the pitolisant group versus 35.1% in the placebo group (P = 0.001); final ESS score ≤10, 36.2% versus 10.5%, respectively (P = 0.005). On the MWT, mean sleep latency increased from 3.5 min to 10.4 min with pitolisant and from 3.4 min to 6.8 min with placebo (P = 0.017). Least-squares mean change in the weekly rate of cataplexy was significantly greater for pitolisant (-14.5; baseline, 23.9; final, 9.4) compared with placebo (-0.1; baseline, 23.1; final, 23.0; P = 0.004). Headache was the most common adverse event with pitolisant.

CONCLUSIONS

Pitolisant, at once-daily doses up to 35.6 mg, was efficacious for reducing excessive daytime sleepiness and cataplexy in patients with severe narcolepsy symptom burden.

Induction of narcolepsy-like symptoms by orexin receptor antagonists in mice

Orexins/hypocretins are hypothalamic neuropeptides that promote and stabilize wakefulness by binding to the orexin receptor type-1 (OX1R) and type-2 (OX2R). Disruption of orexinergic signaling results in the sleep disorder narcolepsy in mice, rats, dogs, and humans. The orexin receptor antagonist suvorexant promotes sleep by blocking both OX1R and OX2R. Whereas suvorexant has been clinically approved for the treatment of insomnia because it is well tolerated in experimental animals as well as in human patients, a logical question remains as to why orexin receptor antagonists do not induce overt narcolepsy-like symptoms. Here we show that acute and chronic suvorexant promotes both rapid eye movement (REM) and non-REM (NREM) sleep without inducing cataplexy in mice. Interestingly, chronic suvorexant increases OX2R mRNA and decreases orexin mRNA and peptide levels, which remain low long after termination of suvorexant administration. When mice are chronically treated with suvorexant and then re-challenged with the antagonist after a 1-week washout, however, cataplexy and sleep-onset REM (SOREM) are observed, which are exacerbated by chocolate administration. Heterozygous orexin knockout mice, with lower brain orexin levels, show cataplexy and SOREM after acute suvorexant administration. Furthermore, we find that acute suvorexant can induce cataplexy and SOREM in wild-type mice when co-administered with chocolate under stress-free (temporally anesthetized) conditions. Taken together, these results suggest that suvorexant can inhibit orexin synthesis resulting in susceptibility to narcolepsy-like symptoms in mice under certain conditions.

γ-Hydroxybutyric Acid: Pharmacokinetics, Pharmacodynamics, and Toxicology

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid present endogenously in the brain and used therapeutically for the treatment of narcolepsy, as sodium oxybate, and for alcohol abuse/withdrawal. GHB is better known however as a drug of abuse and is commonly referred to as the "date-rape drug"; current use in popular culture includes recreational "chemsex," due to its properties of euphoria, loss of inhibition, amnesia, and drowsiness. Due to the steep concentration-effect curve for GHB, overdoses occur commonly and symptoms include sedation, respiratory depression, coma, and death. GHB binds to both GHB and GABAB receptors in the brain, with pharmacological/toxicological effects mainly due to GABAB agonist effects. The pharmacokinetics of GHB are complex and include nonlinear absorption, metabolism, tissue uptake, and renal elimination processes. GHB is a substrate for monocarboxylate transporters, including both sodium-dependent transporters (SMCT1, 2; SLC5A8; SLC5A12) and proton-dependent transporters (MCT1-4; SLC16A1, 7, 8, and 3), which represent significant determinants of absorption, renal reabsorption, and brain and tissue uptake. This review will provide current information of the pharmacology, therapeutic effects, and pharmacokinetics/pharmacodynamics of GHB, as well as therapeutic strategies for the treatment of overdoses. Graphical abstract.

A practical guide to the pharmacological and behavioral therapy of Narcolepsy

Narcolepsy is a rare, chronic, and disabling central nervous system hypersomnia; two forms can be recognized: narcolepsy type 1 (NT1) and narcolepsy type 2 (NT2). Its etiology is still largely unknown, but studies have reported a strong association between NT1 and HLA, as well as a pathogenic association with the deficiency of cerebrospinal hypocretin-1. Thus, the most reliable pathogenic hypothesis is an autoimmune process destroying hypothalamic hypocretin-producing cells. A definitive cure for narcolepsy is not available to date, and although the research in the field is highly promising, up to now, current treatments have aimed to reduce the symptoms by means of different pharmacological approaches. Moreover, overall narcolepsy symptoms management can also benefit from non-pharmacological approaches such as cognitive behavioral therapies (CBTs) and psychosocial interventions to improve the patients' quality of life in both adult and pediatric-affected individuals as well as the well-being of their families. In this review, we summarize the available therapeutic options for narcolepsy, including the pharmacological, behavioral, and psychosocial interventions.

Narcolepsy and psychosis; case report

Narcolepsy is an infrequent neurological disorder, included in the catalog of rare diseases. Despite the existenceof precise diagnostic criteria, this entity remains underdiagnosed. It is characterized by excessive daytime sleepiness associated with cataplexy; in some cases, hypnagogic or hypnopompic hallucinations, auditory hallucinations, and/or delusional ideation may appear. The occurrence of psychotic symptoms makes differential diagnosis extremely difficult (narcolepsy, schizophrenia, or both). Furthermore, therapeutic management may be complex, since the treatment of one of the disorders may worsen the other. Here we describe the case of a patient with this rare comorbidity, which illustrates the major difficulties associated to both differential diagnosis and therapeutic management once a definitive diagnosis has been reached.

Disease symptomatology and response to treatment in people with idiopathic hypersomnia: initial data from the Hypersomnia Foundation registry

OBJECTIVE/BACKGROUND

Knowledge of idiopathic hypersomnia symptomatology derives from clinical case series. Web-based registries provide complementary information by allowing larger sample sizes, with greater geographic and social diversity.

PATIENTS/METHODS

Data were obtained from the Hypersomnia Foundation's online registry. Common clinical features of idiopathic hypersomnia and other central disorders of hypersomnolence were queried, for the last thirty days and when symptoms were most severe. Symptoms were compared between idiopathic hypersomnia participants with and without long sleep durations and between participants with idiopathic hypersomnia and those with either form of narcolepsy. Frequency of medication use and residual symptoms on medication were evaluated.

RESULTS

Five-hundred sixty-three registry respondents were included, with idiopathic hypersomnia (n = 468), narcolepsy type 2 (n = 44), and narcolepsy type 1 (n = 51). "Brain fog," poor memory, and sleep drunkenness were all present in most idiopathic hypersomnia respondents, with brain fog and sleep drunkenness more commonly endorsed by those with long sleep durations. Eighty-two percent of participants with idiopathic hypersomnia were currently treated with medication, most commonly traditional psychostimulants such as amphetamine salts. Among treated patients, symptoms improved while on medication, but substantial residual hypersomnia symptoms remained. Participants with narcolepsy type 1 were more likely than those with idiopathic hypersomnia to endorse intentional and unintentional daytime naps and automatic behaviors.

CONCLUSIONS

Symptoms of idiopathic hypersomnia extend well beyond excessive daytime sleepiness, and these symptoms frequently persist despite treatment. These findings highlight the importance of online registries in identifying gaps in the use and effectiveness of current treatments.

Efficacy and safety of solriamfetol for excessive daytime sleepiness in narcolepsy and obstructive sleep apnea: a systematic review and meta-analysis of clinical trials

INTRODUCTION

Excessive daytime sleepiness (EDS) is the inability to maintain wakefulness and alertness during the major waking episodes of the day, with sleep occurring unintentionally or at inappropriate times. Solriamfetol is a selective norepinephrine-dopamine reuptake inhibitor approved for EDS. This review was done to assess the efficacy and safety of solriamfetol in patients with EDS in narcolepsy or OSA.

METHODS

A systematic search of the electronic database was conducted for relevant studies. Any randomized controlled trial with outcome measures on the efficacy or safety of solriamfetol in EDS were eligible for inclusion. The primary outcomes were mean difference in the maintenance of wakefulness test (MWT), Epworth sleepiness scale (ESS) score, and risk ratio of adverse events. The random-effects model was used to calculate pooled effect estimates.

RESULTS

We identified 336 records from the database search. We analyzed eight articles reported from six clinical trials. We pooled outcome measures from five trials. The overall mean difference for MWT was 9.93 min (95% CI: 8.25-11.61), and the mean difference of ESS score was -4.44 (95% CI: -5.50 to -3.38), both in favor of solriamfetol over placebo. The overall risk ratio of adverse events with solriamfetol was 1.47 (95% CI: 1.28-1.69). The most common adverse events reported were headache, nausea, decreased appetite, anxiety, nasopharyngitis, and insomnia.

CONCLUSIONS

Solriamfetol is efficacious and has a favorable safety profile in the treatment of EDS in patients with narcolepsy and OSA. Solriamfetol is well tolerated and may be recommended for the treatment of EDS in these patients.

[Advances in treatment of narcolepsy]

Narcolepsy is the most common cause of excessive daytime sleepiness (EDS) following obstructive sleep apnea. Its treatment aims to reduce EDS and cataplexy, improve nighttime sleep disturbance, sleep paralysis and sleep-related hallucinations. Pitolisant (a histamine H3 receptor antagonist) and solriamfetol (a norepinephrine reuptake inhibitor) have recently been approved effective for narcolepsy in the United States and the European Union. Pitolisant has proved to be effective for both EDS and cataplexy. Besides being effective on EDS, solriamfetol seems to have advantages in abuse potential and withdrawal syndrome. As potential treatments for EDS and cataplexy associated with narcolepsy, several new drugs are being developed and tested. These new drugs include new hydroxybutyrate preparations (controlled release sodium hydroxybutyrate FT218, low sodium hydroxybutyrate JZP-258), selective norepinephrine reuptake inhibitor (AXS-12), and modafinil combined with astroglial junction protein inhibitor (THN102). This paper reviews the recently approved drugs and potential treatments for narcolepsy.

GHB concentration in a related post-mortem case

Gamma-hydroxybutyrate (GHB) is a central nervous system depressant, primarily used as a recreational drug of abuse and as a therapeutic substance both in U.S.A. and Europe for the treatment of narcolepsy with cataplexy in adult patients and as adjuvant in the control of alcohol withdrawal syndrome. Several cases of GHB related deaths have been reported in the literature and GHB was found alone or in association to other drugs of abuse. However, only few biological matrices are often analyzed, therefore data on GHB distribution are lacking. Here we report a case involving a 45-year-old man, who was found dead in his bedroom.

Solriamfetol for Excessive Sleepiness in Narcolepsy and Obstructive Sleep Apnea

OBJECTIVE

The purpose of this article is to review the available clinical trial data that led to the Food and Drug Administration (FDA) approval of solriamfetol as well as its role in clinical practice.

DATA SOURCES

A MEDLINE/PubMed search was conducted (January 2000 to February 2020) using the keyword solriamfetol to discover appropriate clinical trials.

STUDY SELECTION AND DATA EXTRACTION

Articles were included that were published in the English language and related to the FDA approval of solriamfetol or provided novel information regarding this drug entity.

DATA SYNTHESIS

The findings of the review show that solriamfetol may be a safe and effective option for the treatment of excessive sleepiness (ES) related to narcolepsy and obstructive sleep apnea (OSA).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Solriamfetol is distinguished from other stimulants in that it has lower binding affinity to dopamine and norepinephrine transporters and does not have the monoamine-releasing effects of amphetamines at usual therapeutic doses. Because of solriamfetol's unique mechanism of action, there may be a reduction in abuse potential compared with the other currently FDA-approved options.

CONCLUSIONS

In clinical trials, solriamfetol has shown dose-dependent improvement in wakefulness over placebo and adds another option for clinicians when treating ES in narcolepsy and OSA.

Somnolence Preceded the Development of a Subthalamic Lesion in Neuromyelitis Optica Spectrum Disorder

A 67-year-old woman with neuromyelitis optica spectrum disorder (NMOSD) developed severe somnolence. Ten days after admission, fluid-attenuated inversion-recovery magnetic resonance imaging (MRI) revealed hyperintense areas around the bilateral hypothalamus, which were not present on MRI at admission. The orexin level, which is decreased in idiopathic narcolepsy, was slightly decreased in her cerebrospinal fluid. Immunosuppressive treatment and methylphenidate markedly improved her somnolence. This case shows that NMOSD in the acute phase can cause somnolence in a patient without apparent lesions in the hypothalamus.

Pitolisant: A Review in Narcolepsy with or without Cataplexy

Pitolisant (Wakix^®), an orally available, first-in-class antagonist/inverse agonist of the histamine 3 receptor, is approved in the EU (as of March 2016) for the treatment of narcolepsy with or without cataplexy in adults and in the USA (as of August 2019) for the treatment of excessive daytime sleepiness (EDS) in adults with narcolepsy. Pitolisant was demonstrated to have minimal risk of abuse in preclinical and clinical studies, and is the only anti-narcoleptic drug not scheduled as a controlled substance in the USA. The totality of evidence from pivotal and supportive phase III trials suggests that pitolisant administered at up to the recommended maximum dose of 36 mg once daily reduces EDS and cataplexy in adults with narcolepsy relative to placebo. Noninferiority of pitolisant to modafinil in the management of EDS was not demonstrated. Pitolisant was generally well tolerated in clinical trials. Consistent with its mechanism of action, the most common treatment-emergent adverse events included headache, insomnia and anxiety. With minimal abuse potential and offering the convenience of oral, once-daily administration, pitolisant extends the range of approved treatment options available to adult patients with narcolepsy with or without cataplexy.

Recently Approved and Upcoming Treatments for Narcolepsy

Narcolepsy is a chronic, disabling neurologic disorder characterised by excessive daytime sleepiness (EDS) and, in up to 60% of patients, cataplexy. Treatments for narcolepsy are aimed at improving wakefulness (e.g. modafinil, armodafinil, stimulants), reducing cataplexy attacks (e.g. sodium oxybate, venlafaxine), and treating the symptoms of disturbed nocturnal sleep, sleep paralysis and sleep-related hallucinations (e.g. sodium oxybate). In general, medications that increase the release, or inhibit the reuptake, of norepinephrine or dopamine have wake-promoting effects and are useful in managing EDS, whereas medications that inhibit serotonin or norepinephrine reuptake have anticataplectic effects. Modulation of γ-aminobutyric acid B (GABAB) receptors or histamine H3 receptors (H3Rs) has effects on both EDS and cataplexy. Pitolisant, an H3R antagonist, and solriamfetol, a dopamine and norepinephrine reuptake inhibitor, are the most recently approved treatments for EDS associated with narcolepsy in the European Union (pitolisant) and the USA (pitolisant and solriamfetol). Several new agents are being developed and tested as potential treatments for EDS and cataplexy associated with narcolepsy; these agents include novel oxybate formulations (once-nightly [FT218]; low sodium [JZP-258]), a selective norepinephrine reuptake inhibitor (AXS-12), and a product combining modafinil and an astroglial connexin inhibitor (THN102). This review summarises the mechanisms of action, pharmacokinetics, efficacy, and safety/tolerability of recently approved and emerging treatments for narcolepsy.