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

Armodafinil as Monotherapy in Treating Narcolepsy with Cataplexy

In narcolepsy with cataplexy, sodium oxybate and the recently FDA-approved drug pitolisant are preferred medications. Armodafinil, a longer-acting, non-amphetamine stimulant, is often used in patients who have narcolepsy without cataplexy. It enhances alertness by increasing presynaptic dopamine transmission presynaptically, amplifying serotonin in the cerebral cortex, activating glutamatergic circuits, which may contribute to its vigilance-enhancing properties, and stimulating orexin activity. Armodafinil alone is approved for excessive daytime sleepiness (EDS) symptoms. We report this case of narcolepsy with cataplexy, where armodafinil alone improved the symptoms of not only EDS but also cataplexy. It is known that sodium oxybate, through its gamma-aminobutyric acid type B (GABA-B) receptor agonist activity, helps in cataplexy and EDS. However, in some instances, like this patient, armodafinil alone improves the symptoms of cataplexy and maintains wakefulness.

TAK-861, a potent, orally available orexin receptor 2-selective agonist, produces wakefulness in monkeys and improves narcolepsy-like phenotypes in mouse models

Narcolepsy type 1 (NT1) is associated with severe loss of orexin neurons and characterized by symptoms including excessive daytime sleepiness and cataplexy. Current medications indicated for NT1 often show limited efficacy, not addressing the full spectrum of symptoms, demonstrating a need for novel drugs. We discovered a parenteral orexin receptor 2 (OX2R) agonist, danavorexton, and an orally available OX2R agonist, TAK-994; both improving NT1 phenotypes in mouse models and individuals with NT1. However, danavorexton has limited oral availability and TAK-994 has a risk of off-target liver toxicity. To avoid off-target-based adverse events, a highly potent molecule with low effective dose is preferred. Here, we show that a novel OX2R-selective agonist, TAK-861 [N-{(2S,3R)-4,4-Difluoro-1-(2-hydroxy-2-methylpropanoyl)-2-[(2,3',5'-trifluoro[1,1'-biphenyl]-3-yl)methyl]pyrrolidin-3-yl}ethanesulfonamide], activates OX2R with a half-maximal effective concentration of 2.5 nM and promotes wakefulness at 1 mg/kg in mice and monkeys, suggesting ~ tenfold higher potency and lower effective dosage than TAK-994. Similar to TAK-994, TAK-861 substantially ameliorates wakefulness fragmentation and cataplexy-like episodes in orexin/ataxin-3 and orexin-tTA;TetO DTA mice (NT1 mouse models). Compared with modafinil, TAK-861 induces highly correlated brain-wide neuronal activation in orexin-tTA;TetO DTA mice, suggesting efficient wake-promoting effects. Thus, TAK-861 has potential as an effective treatment for individuals with hypersomnia disorders including narcolepsy, potentially with a favorable safety profile.

Narcolepsy-A Neuropathological Obscure Sleep Disorder: A Narrative Review of Current Literature

Narcolepsy is a chronic, long-term neurological disorder characterized by a decreased ability to regulate sleep-wake cycles. Some clinical symptoms enter into differential diagnosis with other neurological diseases. Excessive daytime sleepiness and brief involuntary sleep episodes are the main clinical symptoms. The majority of people with narcolepsy experience cataplexy, which is a loss of muscle tone. Many people experience neurological complications such as sleep cycle disruption, hallucinations or sleep paralysis. Because of the associated neurological conditions, the exact pathophysiology of narcolepsy is unknown. The differential diagnosis is essential because relatively clinical symptoms of narcolepsy are easy to diagnose when all symptoms are present, but it becomes much more complicated when sleep attacks are isolated and cataplexy is episodic or absent. Treatment is tailored to the patient's symptoms and clinical diagnosis. To facilitate the diagnosis and treatment of sleep disorders and to better understand the neuropathological mechanisms of this sleep disorder, this review summarizes current knowledge on narcolepsy, in particular, genetic and non-genetic associations of narcolepsy, the pathophysiology up to the inflammatory response, the neuromorphological hallmarks of narcolepsy, and possible links with other diseases, such as diabetes, ischemic stroke and Alzheimer's disease. This review also reports all of the most recent updated research and therapeutic advances in narcolepsy. There have been significant advances in highlighting the pathogenesis of narcolepsy, with substantial evidence for an autoimmune response against hypocretin neurons; however, there are some gaps that need to be filled. To treat narcolepsy, more research should be focused on identifying molecular targets and novel autoantigens. In addition to therapeutic advances, standardized criteria for narcolepsy and diagnostic measures are widely accepted, but they may be reviewed and updated in the future with comprehension. Tailored treatment to the patient's symptoms and clinical diagnosis and future treatment modalities with hypocretin agonists, GABA agonists, histamine receptor antagonists and immunomodulatory drugs should be aimed at addressing the underlying cause of narcolepsy.

Changes in Cataplexy Frequency in a Clinical Trial of Lower-Sodium Oxybate with Taper and Discontinuation of Other Anticataplectic Medications

BACKGROUND

Lower-sodium oxybate (LXB) is an oxybate medication with the same active moiety as sodium oxybate (SXB) and a unique composition of cations, resulting in 92% less sodium. LXB was shown to improve cataplexy and excessive daytime sleepiness in people with narcolepsy in a placebo-controlled, double-blind, randomized withdrawal study (NCT03030599). Additional analyses of data from this study were conducted to explore the effects of LXB on cataplexy, including the clinical course and feasibility of transition from other anticataplectics to LXB monotherapy.

OBJECTIVE

The aim of these analyses was to evaluate cataplexy frequency during initiation/optimization of LXB and taper/discontinuation of prior antidepressant/anticataplectic medications.

METHODS

Eligible participants (adults aged 18-70 years with narcolepsy with cataplexy) entered the study taking SXB only (group A), SXB + other anticataplectics (group B), or anticataplectic medication other than SXB (group C), or were cataplexy-treatment naive (group D). LXB was initiated/optimized during a 12-week, open-label, optimized treatment and titration period (OLOTTP). Other anticataplectics were tapered/discontinued during weeks 3-10 of OLOTTP. A 2-week stable-dose period (SDP; during which participants took a stable dose of open-label LXB) and 2-week double-blind randomized withdrawal period (during which participants were randomized to continue LXB treatment or switch to placebo) followed OLOTTP. Treatment-emergent adverse events (TEAEs) were recorded throughout the duration of the study.

RESULTS

At the beginning of OLOTTP, median weekly cataplexy attacks were lower in participants taking SXB at study entry (SXB only [2.00]; SXB + other anticataplectics [0.58]) versus participants who were taking other anticataplectics (3.50) or were anticataplectic naive (5.83). Median weekly cataplexy attacks decreased during weeks 1-2 of OLOTTP in all groups. Increased cataplexy frequency was observed in participants tapering/discontinuing other anticataplectics during weeks 3-10 and was more prominent in participants taking other anticataplectics alone compared with those taking SXB plus other anticataplectics. Cataplexy frequency decreased throughout initiation/optimization in anticataplectic-naive participants. Median number of cataplexy-free days/week at the end of SDP (study week 14) was similar in all groups (6.0, 6.1, 6.0, and 6.2 in groups A, B, C, and D, respectively). During OLOTTP and SDP, TEAEs of worsening cataplexy were reported in 0%, 47.8%, 16.7%, and 2.2% of participants in groups A, B, C, and D, respectively; most TEAEs of worsening cataplexy were reported during tapering/discontinuation of other anticataplectics.

CONCLUSIONS

LXB monotherapy was effective in reducing cataplexy and increasing cataplexy-free days. These results illustrate the feasibility of switching from SXB to LXB while tapering/discontinuing other anticataplectics.

TRIAL REGISTRATION

A Study of the Efficacy and Safety of JZP-258 in Subjects With Narcolepsy With Cataplexy; https://clinicaltrials.gov/ct2/show/NCT03030599 ; clinicaltrials.gov identifier: NCT03030599.

Sleep Disturbances in Patients with Nonepileptic Seizures

OBJECTIVE

Up to 20% of patients treated for epileptic seizures experience psychogenic nonepileptic paroxysms (PNES). These patients present a significant burden for the health care systems because of poor treatment outcomes. The presented review aims to summarize the current state of knowledge on sleep disturbances in patients with nonepileptic seizures.

METHODS

Articles were acquired via PubMed and Web of Science, and papers between January 1990 and March 2020 were extracted. Inclusion criteria were (1) published in a peer-reviewed journal: (2) studies in humans only; or (3) reviews on a related topic; (4) English language. The exclusion criteria were: (1) abstracts from conferences; (2) commentaries; (3) subjects younger than 18 years. From primary assessment, 122 articles were extracted; after obtaining full texts and secondary articles from reference lists, 45 papers were used in this review.

RESULTS

Limited data are available regarding sleep disorders in PNES patients, over the last 30 years only nine original research papers addressed sleep problems in patients with PNES with only six studies assessing objectively measured changes in sleep. Current literature supports the subjective perception of the sleep disturbances with mixed results in objective pathophysiological findings. Conflicting results regarding the REM phase can be found, and studies reported both shortening and prolonging of the REM phase with methodological limitations. Poor sleep quality and shortened duration have been consistently described in most of the studies.

CONCLUSION

Further research on a broader spectrum of patients with PNES is needed, primarily focusing on objective neurophysiological findings. Quality of life in patients suffering from PNES can be increased by good sleep habits and treatment of comorbid sleep disorders.

Living with Narcolepsy: Current Management Strategies, Future Prospects, and Overlooked Real-Life Concerns

Narcolepsy is a neurological disorder of the sleep-wake cycle characterized by excessive daytime sleepiness (EDS), cataplexy, nighttime sleep disturbances, and REM-sleep-related phenomena (sleep paralysis, hallucinations) that intrude into wakefulness. Dysfunction of the hypocretin/orexin system has been implicated as the underlying cause of narcolepsy with cataplexy. In most people with narcolepsy, symptom onset occurs between the ages of 10 and 35 years, but because the disorder is underrecognized and testing is complex, delays in diagnosis and treatment are common. Narcolepsy is treated with a combination of lifestyle modifications and medications that promote wakefulness and suppress cataplexy. Treatments are often effective in improving daytime functioning for individuals with narcolepsy, but side effects and/or lack of efficacy can result in suboptimal management of symptoms and, in many cases, significant residual impairment. Additionally, the psychosocial ramifications of narcolepsy are often neglected. Recently two new pharmacologic treatment options, solriamfetol and pitolisant, have been approved for adults, and the indication for sodium oxybate in narcolepsy has been expanded to include children. In recent years, there has been an uptick in patient-centered research, and promising new diagnostic and therapeutic options are in development. This paper summarizes current and prospective pharmacological therapies for treating both EDS and cataplexy, discusses concerns specific to children and reproductive-age women with narcolepsy, and reviews the negative impact of health-related stigma and efforts to address narcolepsy stigma.

The Risk of Hospitalization for Motor Vehicle Accident Injury in Narcolepsy and the Benefits of Stimulant Use: A Nationwide Cohort Study in Taiwan

STUDY OBJECTIVES

To examine the risk of hospitalization for motor vehicle accident injury (MVAI) in patients with narcolepsy and the effects of stimulant use on MVAI occurrence in patients with narcolepsy.

METHODS

This is a population-based, retrospective cohort study using Taiwan's National Health Insurance Research Database between 2000 and 2013. We included patients with narcolepsy based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, 347. The case and matched control participants were selected in a ratio of 1:3, and the traffic accident (ICD-9-CM codes: E810-E819) plus injury codes (ICD-9-CM codes: 800.xx-999.xx) due to MVAI following hospitalization were used for the study outcome. The type of injury, causes, intentionality, and the effects of stimulant use on patients with narcolepsy were also assessed.

RESULTS

A total of 1,316 participants were enrolled, including 329 participants with narcolepsy and 987 participants without narcolepsy. During a 14-year follow-up period, a total of 104 participants had MVAI, of whom 47 (1,559.54 per 100,000 person-years) belonged to the narcolepsy cohort and 57 (556.21 per 100,000 person-years) to the non-narcolepsy cohort. After adjusting for covariates, the risk of hospitalization for MVAI among participants with narcolepsy was still significantly higher than those without narcolepsy (adjusted hazard ratio = 6.725; 95% confidence interval = 4.421-10.231; P < .001). The use of modafinil or methylphenidate, as monotherapy or combined treatment, was associated with a lower risk of MVAI in the narcolepsy cohort.

CONCLUSIONS

Patients with narcolepsy may have a higher risk of hospitalization for MVAI and stimulant use could mitigate such risk.

Neurobiological and immunogenetic aspects of narcolepsy: Implications for pharmacotherapy

Excessive daytime sleepiness (EDS) and cataplexy are common symptoms of narcolepsy, a sleep disorder associated with the loss of hypocretin/orexin (Hcrt) neurons. Although only a few drugs have received regulatory approval for narcolepsy to date, treatment involves diverse medications that affect multiple biochemical targets and neural circuits. Clinical trials have demonstrated efficacy for the following classes of drugs as narcolepsy treatments: alerting medications (amphetamine, methylphenidate, modafinil/armodafinil, solriamfetol [JZP-110]), antidepressants (tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors), sodium oxybate, and the H₃-receptor inverse agonist/antagonist pitolisant. Enhanced catecholamine availability and regulation of locus coeruleus (LC) norepinephrine (NE) neuron activity is likely central to the therapeutic activity of most of these compounds. LC NE neurons are integral to sleep/wake regulation and muscle tone; reduced excitatory input to the LC due to compromise of Hcrt/orexin neurons (likely due to autoimmune factors) results in LC NE dysregulation and contributes to narcolepsy/cataplexy symptoms. Agents that increase catecholamines and/or LC activity may mitigate EDS and cataplexy by elevating NE regulation of GABAergic inputs from the amygdala. Consequently, novel medications and treatment strategies aimed at preserving and/or modulating Hcrt/orexin-LC circuit integrity are warranted in narcolepsy/cataplexy.

Pseudo Status Cataplecticus in Narcolepsy Type 1

ABSTRACT

The rare constellation of multiple episodes of cataplexy that are refractory to therapy is called status cataplecticus. We describe a young adult with known narcolepsy type 1 who reported a marked exacerbation of her symptoms that was initially suspicious for status cataplecticus. Neurological evaluation, polysomnography, and additional history revealed that the spells were not consistent with cataplexy, but rather with a somatoform disorder. The case highlights the importance of considering psychosomatic factors in narcolepsy type 1 when presumed cataplexy remains suboptimally controlled despite adequate dosing with appropriate medications.

Update on the treatment of narcolepsy: clinical efficacy of pitolisant

Narcolepsy is a neurological disease that affects 1 in 2,000 individuals and is characterized by excessive daytime sleepiness (EDS). In 60-70% of individuals with narcolepsy, it is also characterized by cataplexy or a sudden loss of muscle tone that is triggered by positive or negative emotions. Narcolepsy decreases the quality of life of the afflicted individuals. Currently used drugs treat EDS alone (modafinil/armodafinil, methylphenidate, and amphetamine), cataplexy alone ("off-label" use of antidepressants), or both EDS and cataplexy (sodium oxybate). These drugs have abuse, tolerability, and adherence issues. A greater diversity of drug options is needed to treat narcolepsy. The small molecule drug, pitolisant, acts as an inverse agonist/antagonist at the H3 receptor, thus increasing histaminergic tone in the wake promoting system of the brain. Pitolisant has been studied in animal models of narcolepsy and used in clinical trials as a treatment for narcolepsy. A comprehensive search of online databases (eg, Medline, PubMed, EMBASE, the Cochrane Library Database, Ovid MEDLINE, Europe PubMed Central, EBSCOhost CINAHL, ProQuest Research Library, Google Scholar, and ClinicalTrials.gov) was performed. Nonrandomized and randomized studies were included. This review focuses on the outcomes of four clinical trials of pitolisant to treat narcolepsy. These four trials show that pitolisant is an effective drug to treat EDS and cataplexy in narcolepsy.

New developments in the management of narcolepsy

Narcolepsy is a life-long, underrecognized sleep disorder that affects 0.02%-0.18% of the US and Western European populations. Genetic predisposition is suspected because of narcolepsy's strong association with HLA DQB1*06-02, and genome-wide association studies have identified polymorphisms in T-cell receptor loci. Narcolepsy pathophysiology is linked to loss of signaling by hypocretin-producing neurons; an autoimmune etiology possibly triggered by some environmental agent may precipitate hypocretin neuronal loss. Current treatment modalities alleviate the main symptoms of excessive daytime somnolence (EDS) and cataplexy and, to a lesser extent, reduce nocturnal sleep disruption, hypnagogic hallucinations, and sleep paralysis. Sodium oxybate (SXB), a sodium salt of γ hydroxybutyric acid, is a first-line agent for cataplexy and EDS and may help sleep disruption, hypnagogic hallucinations, and sleep paralysis. Various antidepressant medications including norepinephrine serotonin reuptake inhibitors, selective serotonin reuptake inhibitors, and tricyclic antidepressants are second-line agents for treating cataplexy. In addition to SXB, modafinil and armodafinil are first-line agents to treat EDS. Second-line agents for EDS are stimulants such as methylphenidate and extended-release amphetamines. Emerging therapies include non-hypocretin-based therapy, hypocretin-based treatments, and immunotherapy to prevent hypocretin neuronal death. Non-hypocretin-based novel treatments for narcolepsy include pitolisant (BF2.649, tiprolisant); JZP-110 (ADX-N05) for EDS in adults; JZP 13-005 for children; JZP-386, a deuterated sodium oxybate oral suspension; FT 218 an extended-release formulation of SXB; and JNJ-17216498, a new formulation of modafinil. Clinical trials are investigating efficacy and safety of SXB, modafinil, and armodafinil in children. γ-amino butyric acid (GABA) modulation with GABA_A receptor agonists clarithromycin and flumazenil may help daytime somnolence. Other drugs investigated include GABA_B agonists (baclofen), melanin-concentrating hormone antagonist, and thyrotropin-releasing hormone agonists. Hypocretin-based therapies include hypocretin peptide replacement administered either through an intracerebroventricular route or intranasal route. Hypocretin neuronal transplant and transforming stem cells into hypothalamic neurons are also discussed in this article. Immunotherapy to prevent hypocretin neuronal death is reviewed.

Clinical Approaches to Psychogenic Nonepileptic Seizures

Psychogenic nonepileptic seizures (PNES) are a subtype of conversion disorder (also called functional neurological symptom disorder in DSM-5). Patients with PNES are high utilizers of health care and can have disability levels similar to those of patients with epilepsy. PNES is a common, complex neuropsychiatric somatoform disorder at the interface of neurology and psychiatry disciplines and is largely overlooked and avoided by mental health providers. Despite advances in establishing accurate diagnosis and evidence-based treatments, recent knowledge about PNES has not been well translated into clinical practice. Long diagnostic delays have been associated with poor prognosis. Recent advances in possible neurophysiological biomarkers include functional MRI studies that show abnormalities in emotional, cognitive, executive, and sensorimotor neurocircuits. Although the gold standard for diagnosis is video electroencephalograph, this test is underused by psychiatrists. The International League Against Epilepsy proposed a staged approach to PNES diagnosis using history, semiologic features, and EEG. Thorough psychiatric assessment can identify relevant biopsychosocial and predisposing, precipitating, and perpetuating factors, as well as assess the comorbid psychiatric disorders, which can inform a treatment plan. Clear and thoughtful delivery of diagnosis is the first step in treatment. Regular follow-up with the patient's neurologist, in addition to treatment by mental health professionals familiar with somatic symptom disorders, is recommended. Psychotherapy is the mainstay of treatment, and randomized clinical trials using cognitive-behavioral therapies reveal significant reduction in seizures and other psychiatric symptoms. After centuries, mental health providers now have access to the tools to diagnose and effectively treat PNES and other conversion disorders.

Classics in Chemical Neuroscience: Methylphenidate

As the first drug to see widespread use for the treatment of attention deficit hyperactivity disorder (ADHD), methylphenidate was the forerunner and catalyst to the modern era of rapidly increasing diagnosis, treatment, and medication development for this condition. During its often controversial history, it has variously elucidated the importance of dopamine signaling in memory and attention, provoked concerns about pharmaceutical cognitive enhancement, driven innovation in controlled-release technologies and enantiospecific therapeutics, and stimulated debate about the impact of pharmaceutical sales techniques on the practice of medicine. In this Review, we will illustrate the history and importance of methylphenidate to ADHD treatment and neuroscience in general, as well as provide key information about its synthesis, structure-activity relationship, pharmacological activity, metabolism, manufacturing, FDA-approved indications, and adverse effects.