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

Comparative efficacy of sodium oxybate versus placebo on improvement of nighttime sleep in adult patients with narcolepsy: A systematic review and meta-analysis

Background

Narcolepsy, a central hypersomnolence disorder, disrupts sleep regulation. Sodium oxybate, a CNS (central nervous system) depressant, is widely used as a treatment, but there are surprisingly very few rigorous studies comparing its effectiveness to placebo in adults.

Objectives

To measure the comparative efficacy of sodium oxybate at a dosage regimen of 9 g versus placebo in improving nighttime sleep quality, reducing nocturnal arousals and sleep stage shifts, and enhancing the overall refreshed nature of sleep in adult patients with narcolepsy.

Methods

The methodology included a literature review of PubMed, Cochrane, Scopus, Google Scholar, and Clinicaltrials.gov, retrieving 53 randomized controlled trials (RCT) after removing 14 duplicates. Four studies met the criteria for gauging the efficacy of sodium oxybate compared to placebo in the adult population with narcolepsy. The primary efficacy outcome was improved sleep quality, whereas secondary outcomes were reduced nocturnal arousals and sleep stage shifts with an overall refreshed sleep nature. Analyses used RevMan 5.3 software, and SMD (standardized mean differences) with 95 % CI (confidence intervals) were calculated. Risk and publication biases were measured with Cochrane risk of bias tools and Comprehensive Meta-Analysis Software. Evidence certainty was measured using GRADEpro.

Results

Four RCT involving 1079 participants were analyzed for said outcomes, and relevant forest plots were generated. Statistical analysis showed a substantial improvement in sleep quality [SMD = 0.74(95%Cl:0.53,0.95; p < 0.00001; I2 = 0 %; (high certainty)] and refreshing nature of sleep [SMD = 0.81(95%CI:0.51,1.11; P < 0.00001; I2 = 0 %; (moderate certainty)], reduction in nocturnal arousals [SMD = -0.62(95%CI: 0.92,-0.32; p < 0.00001; I2 = 0 %; (moderate certainty)] and sleep stage shifts [SMD = -1.22(95%CI: 1.46,-0.98; p < 0.00001; I2 = 0 %; (high certainty)]. The risk of bias was located high for one study. Symmetrical funnel plots and Egger's regression intercepts testified to no significant publication bias.

Conclusions

The results showed that sodium oxybate considerably improved the quality of nocturnal sleep, resulting in substantial restorative advantages as well as a decrease in nocturnal arousals and sleep stage transitions. Significant results with low heterogeneity and p-values <0.05, showing consistent effects, were obtained from the analysis. However, overall reliability may be impacted by a high risk of bias in one study.

Narcolepsy and rapid eye movement sleep

Since the first description of narcolepsy at the end of the 19th Century, great progress has been made. The disease is nowadays distinguished as narcolepsy type 1 and type 2. In the 1960s, the discovery of rapid eye movement sleep at sleep onset led to improved understanding of core sleep-related disease symptoms of the disease (excessive daytime sleepiness with early occurrence of rapid eye movement sleep, sleep-related hallucinations, sleep paralysis, rapid eye movement parasomnia), as possible dysregulation of rapid eye movement sleep, and cataplexy resembling an intrusion of rapid eye movement atonia during wake. The relevance of non-sleep-related symptoms, such as obesity, precocious puberty, psychiatric and cardiovascular morbidities, has subsequently been recognized. The diagnostic tools have been improved, but sleep-onset rapid eye movement periods on polysomnography and Multiple Sleep Latency Test remain key criteria. The pathogenic mechanisms of narcolepsy type 1 have been partly elucidated after the discovery of strong HLA class II association and orexin/hypocretin deficiency, a neurotransmitter that is involved in altered rapid eye movement sleep regulation. Conversely, the causes of narcolepsy type 2, where cataplexy and orexin deficiency are absent, remain unknown. Symptomatic medications to treat patients with narcolepsy have been developed, and management has been codified with guidelines, until the recent promising orexin-receptor agonists. The present review retraces the steps of the research on narcolepsy that linked the features of the disease with rapid eye movement sleep abnormality, and those that do not appear associated with rapid eye movement sleep.

Efficacy of Once-Nightly Sodium Oxybate in Patients with Narcolepsy: Post Hoc Analyses of Sensitivity, Effect Size, and Numbers Needed to Treat from the Phase 3 REST-ON Trial

BACKGROUND

Once-nightly sodium oxybate (ON-SXB; LUMRYZ™; FT218) treatment significantly improved the coprimary endpoints of mean sleep latency on the Maintenance of Wakefulness Test (MWT), Clinical Global Impression of Improvement (CGI-I) rating, and number of weekly cataplexy episodes versus placebo in a randomized, placebo-controlled trial (REST-ON). The objective of these post hoc sensitivity analyses was to evaluate the robustness of treatment with ON-SXB, while accounting for missing participant data. Number needed to treat (NNT) and effect size analyses were conducted to quantify the treatment benefits.

METHODS

Participants ≥ 16 years of age with narcolepsy type 1 or 2 were randomized 1:1 to receive ON-SXB (4.5 g [week 1]; 6 g [weeks 2-3]; 7.5 g [weeks 4-8]; or 9 g [weeks 9-13]) or placebo. Sensitivity analyses included completer population, placebo-based multiple imputation (MI) with a missing-not-at-random assumption, analysis of covariance (ANCOVA), and tipping-point-based MI of worsening values until P > 0.05. Mean differences and P-values were calculated for the MWT and number of cataplexy episodes. For CGI-I, odds ratios and P-values were calculated for completers; mean differences (1-7 points; lower values indicate greater improvement) and P-values were calculated using ANCOVA. Effect sizes were calculated using Cohen's d; NNTs were calculated as the inverse of the absolute risk reduction.

RESULTS

In the completer population (ON-SXB, n = 69; placebo, n = 79), all ON-SXB doses demonstrated significant improvements versus placebo for all coprimary endpoints (P < 0.001). All ON-SXB doses demonstrated significant improvements (P < 0.001) versus placebo for all coprimary endpoints when missing values in both treatment arms were imputed from observed values in the placebo arm (i.e., missing data were replaced with placebo data) and when analyzed using ANCOVA. Tipping-point-based analysis on the change from baseline in mean sleep latency on the MWT demonstrated that implausible or nearly implausible baseline MWT assumptions were needed to render the differences between ON-SXB and placebo no longer statistically significant. All doses of ON-SXB had NNTs of three and effect sizes of 0.7-0.9 for MWT response. For the response in terms of number of cataplexy episodes, NNT was six for the 6 g dose and three for the 7.5 g and 9 g doses; the effect sizes were between -0.7 and -0.8. For the Epworth Sleepiness Scale (ESS) response, NNTs ranged from three to six, with a dose-response effect. Effect sizes were between -0.5 and -0.7 for all doses.

CONCLUSIONS

These post hoc results demonstrate the robustness of the REST-ON clinical trial efficacy data.

CLINICAL TRIAL ID

NCT02720744.

Sodium Oxybate: Practical Considerations and Patient Perspectives

Narcolepsy is a rare, chronic sleep disorder with significant impacts on the quality of life of people affected by the disorder. People with narcolepsy (PWN) are a diverse patient population with evolving symptoms, comorbidities, and perspectives. As PWN have varying needs, clinicians should consider a more personalized approach to therapy, including active participation of PWN in their care and shared decision-making between patient and clinician to achieve optimal outcomes. In this review, we discuss the various characteristics and challenges of PWN, present illustrative clinical case scenarios of PWN, provide clinicians with a proposed framework to best address therapy for PWN, and demystify concerns with sodium oxybate.

Assessing Early Efficacy After Initiation of Once-Nightly Sodium Oxybate (ON-SXB; FT218) in Participants with Narcolepsy Type 1 or 2: A Post Hoc Analysis from the Phase 3 REST-ON Trial

BACKGROUND

Once-nightly sodium oxybate (LUMRYZ™; ON-SXB; FT218) significantly improved narcolepsy symptoms in the phase 3 REST-ON trial. The objective of this post hoc analysis was to investigate the early efficacy of ON-SXB at weeks 1 (4.5-g dose) and 2 (6-g dose).

METHODS

In REST-ON, participants (≥ 16 years) with narcolepsy type 1 or 2 were randomized 1:1 to ON-SXB (4.5 g, 1 week; 6 g, 2 weeks; 7.5 g, 5 weeks; 9 g, 5 weeks) or placebo. Protocol-prespecified efficacy assessments were conducted at weeks 3 (6-g dose), 8 (7.5-g dose), and 13 (9-g dose). A post hoc analysis was conducted to assess the early efficacy of ON-SXB, defined as efficacy at weeks 1 (4.5-g dose) and 2 (6-g dose) on Epworth Sleepiness Scale (ESS) score, visual analog scale (VAS) sleep quality, and VAS refreshing nature of sleep. Least squares mean differences (LSMD) in change from baseline to weeks 1 and 2, 95% confidence intervals (CIs), and P values were calculated using mixed-effects models for repeated measures.

RESULTS

In the modified intent-to-treat population (n = 190; ON-SXB, n = 97; placebo, n = 93), baseline ESS scores were 16.6 and 17.5, sleep quality scores were 53.8 and 55.9, and refreshing nature of sleep scores were 46.5 and 49.9 with ON-SXB and placebo, respectively. At week 1 (4.5 g), numerical improvement in ESS score (LSMD [95% CI], - 0.7 [- 1.6 to 0.2]) and significant improvements in sleep quality (3.6 [1.1-6.1]; P < 0.01) and refreshing nature of sleep (3.2 [0.5-5.9]; P < 0.05) were observed with ON-SXB versus placebo. At week 2 (6 g), significant improvements with ON-SXB versus placebo were observed for ESS score (- 1.3 [- 2.4 to - 0.2]; P < 0.02), sleep quality (7.0 [3.8-10.1]; P < 0.001), and refreshing nature of sleep (5.8 [2.3-9.4]; P = 0.001).

CONCLUSIONS

ON-SXB improved daytime sleepiness, sleep quality, and refreshing nature of sleep, with observable benefits beginning in the first week of treatment. These data may help clinicians set expectations with patients.

CLINICAL TRIAL ID

NCT02720744.

Therapeutic Use of γ-Hydroxybutyrate: History and Clinical Utility of Oxybates and Considerations of Once- and Twice-Nightly Dosing in Narcolepsy

Narcolepsy is a rare and chronic hypersomnolence disorder characterized by excessive daytime sleepiness, disrupted nighttime sleep, sleep paralysis, and hypnagogic hallucinations and occurs with or without cataplexy. Orexin neuron loss has been implicated in the underlying pathophysiology of narcolepsy type 1 through dysregulation of sleep/wake patterns and rapid eye movement sleep. γ-Aminobutyric acid (GABA) has been shown to play a role in modulation of orexin neuronal activity during transitions from wakefulness to sleep. γ-Hydroxybutyrate (GHB), an endogenous analog of GABA, has demonstrated therapeutic benefit in treatment of narcolepsy through early investigations, but use has historically been limited owing to existing stigma related to illicit use and abuse risk. Initial regulatory approval of its sodium salt derivative, sodium oxybate (SXB), for cataplexy in patients with narcolepsy occurred in 2002, and additional formulations have been developed. The efficacy and safety of SXB in narcolepsy have been supported by decades of clinical use and research. This review discusses the history and clinical application of GHB and its SXB derivatives in the treatment of individuals with narcolepsy, including clinical safety and effect on sleep.

Impaired sleep-dependent memory consolidation in pediatric narcolepsy type 1

STUDY OBJECTIVES

Disrupted nighttime sleep is common in pediatric narcolepsy type 1, yet its cognitive impact is unknown. As N2 sleep spindles are necessary for sleep-dependent memory consolidation, we hypothesized that narcolepsy type 1 impairs memory consolidation via N2 sleep fragmentation and N2 sleep spindle alterations.

METHODS

We trained 28 pediatric narcolepsy type 1 participants and 27 healthy controls (HCs) on a spatial declarative memory task before a nocturnal in-lab polysomnogram and then gave them a cued recall test upon awakening in the morning. We extracted wake and sleep stage bout numbers and N2 spindle characteristics from the polysomnogram and conducted mixed model analysis of sleep-dependent memory consolidation to identify group differences.

RESULTS

Narcolepsy type 1 participants had shorter N2 bout durations and associated shorter N2 spindles versus HC, but other N2 spindle features were similar. Narcolepsy type 1 participants had worse memory performance postsleep than HCs after adjusting for age and gender (mean memory consolidation HC: -3.1% ± 18.7, NT1: -15.6 ± 24.8, main effect group × time of testing F = 5.3, p = .03). We did not find significant relationships between sleep-dependent memory consolidation and N2 spindle characteristics. Notably, increased N1% was associated with worse sleep-dependent memory consolidation with results driven by the narcolepsy type 1 group.

CONCLUSIONS

Sleep-dependent memory consolidation is mildly impaired in youth with narcolepsy type 1 and findings may be attributed to increases in N1 sleep. Further studies are needed to determine if these findings are generalizable and reversible with sleep-based therapies.

Characterizing disrupted nighttime sleep and associated functional outcomes in youth with narcolepsy type 1

STUDY OBJECTIVES

Disrupted nighttime sleep and sleep instability are common in children and adolescents with narcolepsy type 1, but optimal objective sleep measures have not been determined. We compared self-reported and objective sleep measures between young people with narcolepsy type 1 and healthy controls and test the hypotheses that the wake/non-rapid eye movement sleep stage 1 (N1) index is the best objective measure of perceived nocturnal wakings vs other disrupted nighttime sleep measures reported in the literature and is associated with daytime functional problems.

METHODS

n = 26 healthy controls and n = 27 narcolepsy type 1 participants ages 8-21 years completed a 15-item habitual sleep quality survey and an in-lab polysomnogram. We compared group survey responses and performed stepwise regression of sleep quality and instability measures with a survey question ("During the night, I wake more than once"). Last, we used logistic regression to identify associations between the wake/N1 index with daytime functional concerns across groups.

RESULTS

Compared to healthy controls, narcolepsy type 1 participants reported more frequent restless sleep, nighttime moaning/groaning/talking, tossing and turning, and nocturnal wakings (all P values < .01), but no greater difficulties in falling asleep or returning back to sleep. Across groups, self-reported waking from sleep was associated with increased wake/N1 index and selective serotonin reuptake inhibitor/selective norepinephrine re-uptake inhibitor use. The wake/N1 index was associated with daytime fatigue but no other behavioral or cognitive concerns.

CONCLUSIONS

Disrupted nighttime sleep is a multifactorial complaint that differs from insomnia. We believe the wake/N1 index is a useful sleep instability measure that should be helpful in research and as a treatment target in clinical practice, especially for fatigue concerns.

CITATION

Heckler G, Worhach J, Wang G, et al. Characterizing disrupted nighttime sleep and associated functional outcomes in youth with narcolepsy type 1. J Clin Sleep Med. 2025;21(2):355-363.

RESTORE: Once-nightly oxybate dosing preference and nocturnal experience with twice-nightly oxybates

Objective/Background

Preference for extended-release, once-nightly sodium oxybate (ON-SXB, FT218) vs twice-nightly immediate-release (IR) oxybate was assessed in participants switching from IR oxybate to ON-SXB in an open-label/switch study, RESTORE (NCT04451668).

Patients/Methods

Participants aged ≥16 years with narcolepsy who completed the phase 3 REST-ON trial, were oxybate-naive, or were on a stable IR oxybate dose (≥1 month) were eligible for RESTORE. For participants who switched from twice-nightly dosing to ON-SXB, initial doses were closest or equivalent to their previous nightly IR oxybate dose. These participants completed a questionnaire at baseline about nocturnal adverse events associated with the middle-of-the-night IR oxybate dose in the preceding 3 months, a preference questionnaire after 3 months of stable-dose ON-SXB, and an end-of-study (EOS) questionnaire.

Results

There were 130 switch participants; 92/98 (93.9 %) who completed the preference questionnaire preferred ON-SXB. At baseline, 69.2 % reported missing their second IR oxybate dose at least once; in these cases, 80 % felt worse the next day. Approximately 39 % reported taking a second nightly IR oxybate dose >4 h after the first dose, 51 % of whom felt somewhat to extremely groggy/unsteady the next morning; 120 participants (92 %) reported getting out of bed after their second oxybate dose. Of those, 9 (8 %) reported falls and 5 (4 %) reported injuries. Of the switch participants who completed the EOS questionnaire, 91.2 % felt better able to follow the recommended ON-SXB dosing schedule.

Conclusions

The second nightly IR oxybate dose presents significant treatment burdens and adherence concerns. Participants overwhelmingly preferred the once-nightly dosing regimen of ON-SXB.

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.

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.

Weight Loss With Once-nightly Sodium Oxybate for the Treatment of Narcolepsy: Analysis From the Phase III Randomized study Evaluating the efficacy and SafeTy of a ONce nightly formulation of sodium oxybate (REST-ON) Trial

PURPOSE

Individuals with narcolepsy are more likely to be obese than the general population. Changes in weight-related measures with extended-release, once-nightly sodium oxybate (ON-SXB) and characteristics of participants with ≥5% weight loss were assessed in a Randomized study Evaluating the efficacy and SafeTy of a ONce nightly formulation of sodium oxybate (REST-ON) trial post hoc analysis.

METHODS

REST-ON (NCT02720744) was a Phase III, double-blind, placebo-controlled, multicenter, randomized clinical trial. Participants aged ≥16 years with narcolepsy type 1 (NT1) or NT2 received ON-SXB or placebo for 13 weeks (week 1, 4.5 g; weeks 2-3, 6 g; weeks 4-8, 7.5 g; and weeks 9-13, 9 g). Weight and body mass index were measured at baseline and study end.

FINDINGS

Weights were similar between groups at baseline (mean [SD]; ON-SXB, 81.2 [20.8] kg; N = 107 [NT1, n = 80; NT2, n = 27]; placebo, 82.1 [22.5] kg; N = 105 [NT1, n = 82; NT2, n = 23]). At week 13 (9 g), mean (SD) weight decreased 1.3 (3.6) kg with ON-SXB and increased 0.2 (2.6) kg with placebo; 17.8% (19/107; NT1, n = 14; NT2, n = 5) of participants receiving ON-SXB had ≥5% weight loss versus 3.8% receiving placebo (4/105; NT1, n = 3; NT2, n = 1; P = 0.001). At week 13, least squares mean (SE) body mass index change from baseline was ‒0.51 (0.13) kg/m2 with ON-SXB and 0.08 (0.13) kg/m2 with placebo (least squares mean difference [95% CI], -0.59 [-0.95 to -0.23] kg/m2; P = 0.001). Excessive daytime sleepiness improved for both groups with ON-SXB, the ≥5% weight-loss subgroup exhibited larger improvement in the Maintenance of Wakefulness Test and Epworth Sleepiness Scale versus the other subgroup (weight loss <5%, no change, or weight gain) (Maintenance of Wakefulness Test, P = 0.019; Epworth Sleepiness Scale score, P < 0.001).

IMPLICATIONS

Narcolepsy is often associated with obesity, which may increase cardiometabolic risks. ON-SXB, an effective treatment for excessive daytime sleepiness and cataplexy, may be preferred in overweight or obese individuals to provide a more tailored treatment approach.

CLINICALTRIALS

GOV IDENTIFIER

NCT02720744.

Effects of intraoperative sodium oxybate infusion on post-operative sleep quality in patients undergoing gynecological laparoscopic surgery: A randomized clinical trial

STUDY OBJECTIVE

Post-operative sleep quality is an important factor that influences post-operative recovery. Sodium oxybate has been used to treat sleep disturbances associated with various pathological conditions. However, whether intraoperative intravenous infusion of sodium oxybate improves post-operative sleep quality is unknown. This study aimed to examine the effects of sodium oxybate on the post-operative sleep quality of patients who underwent gynecological laparoscopic surgery.

DESIGN

A single-center, prospective, two-arm, double-blinded randomized controlled trial.

SETTING

The Shengjing Hospital of China Medical University in Liaoning, China.

PATIENTS

We enrolled 180 adult patients (90 for each group) undergoing elective gynecological laparoscopic surgery, and 178 patients (89 for each group) were included in the final analysis.

INTERVENTIONS

Patients were randomly allocated in a 1:1 ratio to receive either sodium oxybate (30 mg kg-1) or an equivalent volume of saline after intubation. The patients, anesthetists, and follow-up staff were blinded to group assignment.

MEASUREMENTS

The primary outcome was sleep quality measured using the Richards-Campbell Sleep Questionnaire (RCSQ) on post-operative days (PODs) one and three. Secondary outcomes included post-operative pain measured using the visual analog scale, sleep quality at one and three months post-operatively measured using the Pittsburgh Sleep Quality Index, and factors associated with post-operative sleep quality.

MAIN RESULTS

Analysis with generalized estimating equations showed that sodium oxybate significantly improved post-operative sleep quality, as represented by increased total RCSQ scores (mean difference (95% CI); 9 (2, 16), P = 0.010) over PODs one and three. There was no difference in post-operative pain between the two groups over PODs one and three or in post-operative sleep quality over one and three months post-operatively. Age, surgery type, start time of surgery, and use of sufentanil-based patient-controlled intravenous analgesia were significantly associated with post-operative sleep quality.

CONCLUSIONS

Intraoperative sodium oxybate infusion improved post-operative sleep in patients who underwent gynecological laparoscopic surgery.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, Clinical trial number: ChiCTR2200061460.

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.

Efficacy of once-nightly sodium oxybate (FT218) in narcolepsy type 1 and type 2: post hoc analysis from the Phase 3 REST-ON Trial

STUDY OBJECTIVES

Post hoc analyses from the phase 3 REST-ON trial evaluated efficacy of extended-release once-nightly sodium oxybate (ON-SXB; FT218) vs placebo for daytime sleepiness and disrupted nighttime sleep in narcolepsy type 1 (NT1) and 2 (NT2).

METHODS

Participants were stratified by narcolepsy type and randomized 1:1 to ON-SXB (4.5 g, week 1; 6 g, weeks 2-3; 7.5 g, weeks 4-8; and 9 g, weeks 9-13) or placebo. Assessments included mean sleep latency on Maintenance of Wakefulness Test (MWT) and Clinical Global Impression-Improvement (CGI-I) rating (coprimary endpoints) and sleep stage shifts, nocturnal arousals, and patient-reported sleep quality, refreshing nature of sleep, and Epworth Sleepiness Scale (ESS) score (secondary endpoints) separately in NT1 and NT2 subgroups.

RESULTS

The modified intent-to-treat population comprised 190 participants (NT1, n = 145; NT2, n = 45). Significant improvements were demonstrated with ON-SXB vs placebo in sleep latency for NT1 (all doses, p < .001) and NT2 (6 and 9 g, p < .05) subgroups. Greater proportions of participants in both subgroups had CGI-I ratings of much/very much improved with ON-SXB vs placebo. Sleep stage shifts and sleep quality significantly improved in both subgroups (all doses vs placebo, p < .001). Significant improvements with all ON-SXB doses vs placebo in refreshing nature of sleep (p < .001), nocturnal arousals (p < .05), and ESS scores (p ≤ .001) were reported for NT1 with directional improvements for NT2.

CONCLUSIONS

Clinically meaningful improvements of a single ON-SXB bedtime dose were shown for daytime sleepiness and DNS in NT1 and NT2, with less power for the limited NT2 subgroup.

Clinician Preferences for Oxybate Treatment for Narcolepsy: Survey and Discrete Choice Experiment

INTRODUCTION

Immediate-release sodium oxybate (SXB) has been Food and Drug Administration (FDA)-approved to treat narcolepsy since 2002; in 2020, a mixed-salt oxybates formulation was also approved. Both are taken at bedtime with a second dose taken 2.5-4 h later. A third oxybate option, an investigational extended-release SXB, may soon be available. This study was undertaken to understand clinicians' preferences between these 3 different oxybate treatments.

METHODS

Clinicians in active clinical practice for 3-35 years and experience treating patients with narcolepsy were recruited. A 30-min web-based survey quantified narcolepsy disease-state attitudes, treatment perceptions, and satisfaction with oxybates on 9-point scales. A discrete choice experiment (DCE) of 12 choice sets, with 2 hypothetical treatment profiles in each, was used to capture clinician preferences about overall oxybate therapy preference, impact on patient quality of life (QoL), and patient anxiety/stress. Attributes associated with current therapies and those expected to be available in the near future were included in the design.

RESULTS

The clinicians surveyed (n = 100) indicated that narcolepsy has a negative impact on patient QoL (mean rating, 7.7) and rated impact on QoL and treatment efficacy as the most important aspects of a narcolepsy treatment (mean rating, 7.3-7.7). Clinicians with experience prescribing oxybates had moderately high satisfaction with SXB and mixed-salt oxybates efficacy (mean ratings, 6.5-6.9) and safety (mean ratings, 6.1-6.7) and lower satisfaction with nightly dosing frequency (mean rating, 5.9 and 6.3, respectively). In the DCE, dosing frequency was the most important attribute driving overall product choice, patient QoL, and reducing patient anxiety/stress (relative attribute importance, 46.1, 41.7, and 44.0, respectively), with once nightly preferred over twice nightly.

CONCLUSION

Clinicians indicated a significantly higher preference for the once-at-bedtime dosing schedule versus twice nightly in selecting oxybate therapies overall and when aiming to improve patient QoL or reduce patient anxiety.

Calcium, magnesium, potassium, and sodium oxybates oral solution for cataplexy or excessive daytime sleepiness associated with narcolepsy

INTRODUCTION

Lower-sodium oxybate (LXB) is a novel formulation that is approved by the US Food and Drug Administration (FDA) to treat cataplexy and excessive daytime sleepiness (EDS) in adult patients and children ≥ 7 years with narcolepsy. LXB contains 92 percent less sodium than sodium oxybate (SXB), which adds 550-1640 mg of sodium/day at usual doses of 3-9 grams per day. The FDA has declared LXB to be clinically superior to SXB due to greater safety by reducing the chronic sodium load. Narcolepsy patients have high comorbidities for hypertension and cardiovascular disease, conditions which can be adversely affected by high sodium intake.

AREAS COVERED

This drug review discusses narcolepsy, current and upcoming pharmacotherapy, and LXB chemistry, pharmacodynamics, pharmacokinetics, and metabolism. Published results from LXB's phase 1 studies, a phase 3 study, and 2 post-marketing studies are reviewed. Databases searched included Pubmed, Google Scholar, Lexi-Comp, Scopus, Science, and Ovid.

EXPERT OPINION

LXB is efficacious in treating daytime sleepiness and cataplexy in adults and children ≥ 7 years with narcolepsy. Using LXB instead of SXB formulations may benefit narcolepsy patients with cardiovascular comorbidities and hypertension, but long-term studies are needed to prove it.