The Pharmacokinetics of Sodium Oxybate Oral Solution following Acute and Chronic Administration to Narcoleptic Patients

This trial was conducted to evaluate the pharmacokinetics and safety of a sodium oxybate (gamma-hydroxybutyrate [GHB]) oral solution in narcoleptic patients after acute and chronic treatment. An open-label, two-period, two-treatment study design was used. Trial subjects included 13 patients with polysomnographically confirmed narcolepsy. The patients were administered a bedtime dose of 4.5 g of sodium oxybate while in a sleep research center. They were subsequently treated with sodium oxybate at the nightly dose of 4.5 g for 8 weeks. The patients then returned to the sleep center and were again treated with the 4.5-g sodium oxybate dose at bedtime. Blood samples (5 mL) were collected at 18 time points before and up to 7 hours after both the first dose of sodium oxybate and following 8 weeks of dosing. Plasma samples were analyzed for oxybate content by a validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. Noncompartmental methods were applied in the determination of pharmacokinetic parameters from each patient's plasma oxybate concentration versus time curve. No serious adverse events were recorded, and all patients completed the study. Headache, enuresis, and leg cramps were reported as adverse experiences. With both acute and chronic dosing, sodium oxybate was rapidly absorbed and eliminated with an apparent half-life of about 40 minutes. The only changes observed in the kinetics of oxybate after 8 weeks of treatment were a 13% and 16% increase in peak concentration (C(max)) and systemic exposure (AUC), respectively. The pharmacokinetics of sodium oxybate in narcoleptic patients were not changed in any clinically significant manner when the drug was chronically administered. The drug was well tolerated.

Effects of oral L-carnitine administration in narcolepsy patients: a randomized, double-blind, cross-over and placebo-controlled trial

Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness, cataplexy, and rapid eye movement (REM) sleep abnormalities. A genome-wide association study (GWAS) identified a novel narcolepsy-related single nucleotide polymorphism (SNP), which is located adjacent to the carnitine palmitoyltransferase 1B (CPT1B) gene encoding an enzyme involved in β-oxidation of long-chain fatty acids. The mRNA expression levels of CPT1B were associated with this SNP. In addition, we recently reported that acylcarnitine levels were abnormally low in narcolepsy patients. To assess the efficacy of oral l-carnitine for the treatment of narcolepsy, we performed a clinical trial administering l-carnitine (510 mg/day) to patients with the disease. The study design was a randomized, double-blind, cross-over and placebo-controlled trial. Thirty narcolepsy patients were enrolled in our study. Two patients were withdrawn and 28 patients were included in the statistical analysis (15 males and 13 females, all with HLA-DQB1*06:02). l-carnitine treatment significantly improved the total time for dozing off during the daytime, calculated from the sleep logs, compared with that of placebo-treated periods. l-carnitine efficiently increased serum acylcarnitine levels, and reduced serum triglycerides concentration. Differences in the Japanese version of the Epworth Sleepiness Scale (ESS) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) vitality and mental health subscales did not reach statistical significance between l-carnitine and placebo. This study suggests that oral l-carnitine can be effective in reducing excessive daytime sleepiness in narcolepsy patients.

A practical guide to the therapy of narcolepsy and hypersomnia syndromes

Narcolepsy and other syndromes associated with excessive daytime sleepiness can be challenging to treat. New classifications now distinguish narcolepsy/hypocretin deficiency (also called type 1 narcolepsy), a lifelong disorder with well-established diagnostic procedures and etiology, from other syndromes with hypersomnolence of unknown causes. Klein-Levin Syndrome, a periodic hypersomnia associated with cognitive and behavioral abnormalities, is also considered a separate entity with separate therapeutic protocols. Non hypocretin-related hypersomnia syndromes are diagnoses of exclusion. These diagnoses are only made after eliminating sleep deprivation, sleep apnea, disturbed nocturnal sleep, and psychiatric comorbidities as the primary cause of daytime sleepiness. The treatment of narcolepsy/hypocretin deficiency is well-codified, and involves pharmacotherapies using sodium oxybate, stimulants, and/or antidepressants, plus behavioral modifications. These therapies are almost always needed, and the risk-to-benefit ratio is clear, notably in children. Detailed knowledge of the pharmacological profile of each compound is needed to optimize use. Treatment for other syndromes with hypersomnolence is more challenging and less codified. Preferably, therapy should be conservative (such as modafinil, atomoxetine, behavioral modifications), but it may have to be more aggressive (high-dose stimulants, sodium oxybate, etc.) on a case-by-case, empirical trial basis. As cause and evolution are unknown in these conditions, it is important to challenge diagnosis and therapy over time, keeping in mind the possibility of tolerance and the development of stimulant addiction. Kleine-Levin Syndrome is usually best left untreated, although lithium can be considered in severe cases with frequent episodes. Guidelines are provided based on the literature and personal experience of the author.

[Narcolepsy in a seven-year-old girl]

Narcolepsy is a life-long disease commonly diagnosed in adults. Although the first symptoms often appear during childhood, paediatric narcolepsy is often underrecognised and underdiagnosed. The presentation can be very variable, this making diagnosis difficult. We describe a paediatric case with narcolepsy. The patient had the typical symptoms with excessive daytime sleepiness, sleep attacks and cataplexy. The aim of this case report is to draw paediatricians' attention to childhood narcolepsy. An early and sufficient treatment is necessary to avoid socio-emotional disorders and poor school performance in these patients.

[Diagnostic and therapeutic update in narcolepsy]

Narcolepsy is an emblematic, unique disease within sleep disorders that is characterised by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep. In the last 14 years truly spectacular progress has been made in our knowledge of this disease, since the discovery of its cause, i.e. a loss of the hypothalamic neurons that synthesise hypocretin, a previously unknown neurotransmitter, and its probable aetiopathogenic mechanisms, i.e. an autoimmune process in a patient with very precise immunological characteristics - a specific type of HLA and a specific type of T-cell receptor. The cause of this autoimmune process remains unknown. The definitive treatment - the administration of hypocretin, which is the substance missing in the organism - is still unavailable, but there are powerful drugs for treating its main symptoms, the sleepiness and the cataplexy. Some of these are classic compounds (methylphenidate, clomipramine), while others are more recent (modafinil, venlafaxine, sodium oxybate), but together they allow many patients to experience significant improvements. Lack of knowledge about the disease, both on the part of patients and their relatives as well as physicians, is the reason for the great delay in its diagnosis, with even more dramatic consequences when the disease begins in infancy.

Excessive daytime sleepiness and narcolepsy--an approach to investigation and management

Excessive daytime sleepiness is a common presentation to physicians both in general practice and hospital settings. In this review, we provide an update on the latest theories on the pathogenesis of the condition, and discuss the approach to investigation of the sleepy patient, with particular reference to narcolepsy. Recommended therapy is reviewed for both narcolepsy and cataplexy, to provide physicians with an important reference on the investigation and management of these troubling conditions.

Narcolepsy in New Zealand: pathway to diagnosis and effect on quality of life

AIMS

There has been no attempt to survey New Zealanders with narcolepsy to determine their pathway to diagnosis, symptoms, treatment, or quality of life. We therefore aimed to develop a comprehensive questionnaire, and compare responses on measures of daytime sleepiness and quality of life between individuals with narcolepsy and the general New Zealand population.

METHODS

A questionnaire was developed encompassing descriptive information, daytime sleepiness and sleep habits, general health and wellbeing, diagnosis and treatment of narcolepsy, symptoms, and quality of life. Ninety-two individuals were identified through medical specialists and a local support group.

RESULTS

Complete responses were obtained from 54 individuals (63% female, mean age 54.7 ± 18.3 years). The mean Epworth Sleepiness Scale score was 16.4 ± 5.4 (/24). Symptoms first appeared at 20.7 ± 9.7 years of age on average, although diagnosis did not take place until 33.4 ± 13.8 years of age. Individuals with narcolepsy reported substantially lower health-related quality of life than the general New Zealand population. Less than half of those diagnosed with narcolepsy had undergone an objective evaluation including a sleep study.

CONCLUSIONS

New Zealanders with narcolepsy suffer from an excessive level of daytime sleepiness, and have significantly poorer health-related quality of life than the general population. There are a number of inconsistencies between the diagnostic pathway in New Zealand and best-practice guidelines for diagnosis and treatment.

Effect of sodium oxybate on growth hormone secretion in narcolepsy patients and healthy controls

Hypocretin deficiency causes narcolepsy and may affect neuroendocrine systems and body composition. Additionally, growth hormone (GH) alterations my influence weight in narcolepsy. Symptoms can be treated effectively with sodium oxybate (SXB; γ-hydroxybutyrate) in many patients. This study compared growth hormone secretion in patients and matched controls and established the effect of SXB administration on GH and sleep in both groups. Eight male hypocretin-deficient patients with narcolepsy and cataplexy and eight controls matched for sex, age, BMI, waist-to-hip ratio, and fat percentage were enrolled. Blood was sampled before and on the 5th day of SXB administration. SXB was taken two times 3 g/night for 5 consecutive nights. Both groups underwent 24-h blood sampling at 10-min intervals for measurement of GH concentrations. The GH concentration time series were analyzed with AutoDecon and approximate entropy (ApEn). Basal and pulsatile GH secretion, pulse regularity, and frequency, as well as ApEn values, were similar in patients and controls. Administration of SXB caused a significant increase in total 24-h GH secretion rate in narcolepsy patients, but not in controls. After SXB, slow-wave sleep (SWS) and, importantly, the cross-correlation between GH levels and SWS more than doubled in both groups. In conclusion, SXB leads to a consistent increase in nocturnal GH secretion and strengthens the temporal relation between GH secretion and SWS. These data suggest that SXB may alter somatotropic tone in addition to its consolidating effect on nighttime sleep in narcolepsy. This could explain the suggested nonsleep effects of SXB, including body weight reduction.

Severe mania complicating treatment of narcolepsy with cataplexy

We report the case of a 22-year-old male who exhibited severe manic behavior shortly after beginning treatment with modafinil and venlafaxine for narcolepsy with cataplexy. The manic episode persisted several weeks after medication cessation and required management with a mood stabilizer. Reinstitution of modafinil and an alternate antidepressant for recurrent sleepiness and cataplexy was well tolerated and very effective. Sleep physicians should be aware that psychostimulants, including modafinil, and antidepressant medications commonly prescribed for treatment of narcolepsy may precipitate mania in patients with underlying bipolar disorder.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The nightly use of sodium oxybate is associated with a reduction in nocturnal sleep disruption: a double-blind, placebo-controlled study in patients with narcolepsy

OBJECTIVE

To further explore the effects of sodium oxybate (SXB) administration on nocturnal sleep in narcolepsy patients during a double-blind, placebo-controlled, parallel group study conducted with 228 adult patients with narcolepsy/cataplexy in the United States, Canada, and Europe.

METHOD

Patients were withdrawn from antidepressants and sedative/hypnotics, and then randomized to receive 4.5, 6, or 9 g SXB or placebo nightly for 8 weeks. Patients receiving 6 and 9 g/night doses were titrated to their final dose in weekly 1.5 g increments, while patients receiving placebo were randomized to undergo a similar mock dose titration. The use of stimulant therapy continued unchanged. Changes in sleep architecture were measured using centrally scored nocturnal polysomnograms. Daily diaries were used to record changes in narcolepsy symptoms and adverse events.

RESULTS

Following 8 weeks of SXB treatment, study patients demonstrated significant dose-related increases in the duration of stage 3 and 4 sleep, reaching a median increase of 52.5 minutes in patients receiving 9 g nightly. Compared to placebo-treated patients, delta power was significantly increased in all dose groups. Stage 1 sleep and the frequency of nocturnal awakenings were each significantly decreased at the 6 and 9 g/night doses. The changes in nocturnal sleep coincided with significant decreases in the severity and frequency of narcolepsy symptoms.

CONCLUSIONS

The nightly administration of SXB to narcolepsy patients significantly impacts measures of slow wave sleep, wake after sleep onset, awakenings, total sleep time, and stage 1 sleep in a dose-related manner. The frequency and severity of narcolepsy symptoms decreased with treatment.

Narcolepsy in adolescents

Narcolepsy is a disorder of children and adolescence, but until recently it was often not identified until adulthood, with a reported time from onset to diagnosis of about a decade. This disorder affects approximately 0.05% of the population and starts in childhood and adolescence about half of the time. With narcolepsy, the boundaries between wake, sleep, and dreams are blurred. The cardinal features of narcolepsy-cataplexy are daytime somnolence, cataplexy (sometimes occurring long after onset of sleepiness), sleep paralysis, and hypnagogic hallucinations. Weight gain, disturbed nocturnal sleep, and social/school functional changes are common; reactive substance use to maintain wakefulness during the day may also be seen. Males and females are equally affected. It is classically associated with HLA DQB1*0602, the most specific genetic marker for narcolepsy across all ethnic groups. CSF hypocretin has recently been found to be depleted in this disorder, and late-breaking data support that the disease is caused by autoimmune destruction of hypocretin-producing neurons in the hypothalamus. There is no known cure for narcolepsy. Therapies include behavioral/ scheduling modification, medications to combat daytime sleepiness and cataplexy, and treatment of concomitant disorders leading to daytime sleepiness. The differential diagnosis for this disorder should include other disorders of excessive daytime sleepiness with a proclivity toward onset in adolescence, such as delayed sleep phase syndrome, obstructive sleep apnea, and insufficient sleep time; substance use; and less commonly neurologic disorders such as Klein Levin syndrome, Prader-Willi syndrome, and others. Immunomodulator therapy and hypocretin replacement are proposed therapies that hold promise for the future.

Pharmacotherapy in pediatric sleep disorders

Sleep disorders are highly prevalent during childhood and adolescence. It is known that if left untreated, these problems can have significant impact on daytime function, including learning, memory, attention, and behavior. The approach to the treatment of these disorders (whether with or without pharmacotherapy) is dependent on a thorough evaluation of the sleep complaint and determination of an accurate diagnosis. Many pediatric sleep problems are due to insomnia. There is good evidence that young children with behaviorally based insomnia respond to appropriate behavioral interventions. There is less research evidence of the efficacy of these interventions in children who are either school age or adolescents; however, nonpharmacologic strategies are usually indicated initially in the approach to treatment. The indication for the use of pharmacotherapy in pediatric insomnia is not well understood; however, some general principles are described when medications may be considered. There are specific sleep disorders (other than insomnia) for which pharmacotherapy plus behavioral strategies are warranted. The research regarding pharmacotherapy in pediatric sleep disorders is limited; often, medications are used "off label" based on data extrapolated from adult studies. Clinicians who suggest over-the-counter treatments or prescribe medications for pediatric patients with sleep disorders should have an understanding of the classification of sleep disorders and the role of pharmacotherapy in the treatment of these disorders. In this chapter, the emphasis is on the pharmacologic treatment of sleep disorders in typically developing children and adolescents.

The long-term tolerability and efficacy of armodafinil in patients with excessive sleepiness associated with treated obstructive sleep apnea, shift work disorder, or narcolepsy: an open-label extension study

STUDY OBJECTIVES

Armodafinil is a wakefulness-promoting medication. Its efficacy and tolerability have been established in 12-week studies of patients with excessive sleepiness (ES) associated with treated obstructive sleep apnea (OSA), shift work disorder (SWD), or narcolepsy. This study evaluated the tolerability and efficacy of armodafinil for > or = 12 months.

METHODS

Patients with ES associated with treated OSA, SWD, or narcolepsy who completed one of four 12-week, double-blind studies were eligible for this multicenter, open-label study of > or = 12 months' duration of treatment with armodafinil (50 to 250 mg/day). Adverse events and other criteria of tolerability were monitored throughout the study. Efficacy assessments included the Clinical Global Impression of Change (CGI-C), Brief Fatigue Inventory (BFI), and Epworth Sleepiness Scale (ESS).

RESULTS

Of 743 enrolled patients (474 with treated OSA, 113 with SWD, and 156 with narcolepsy), 57% of patients (420/743) completed 12 months or more of treatment. Discontinuations due to adverse events occurred in 13% of patients (95/743) during the initial 12-month period. Throughout the > or = 12-month study, adverse events were generally of mild-to-moderate intensity; headache (25% [180/731]), nasopharyngitis (17% [123/731]), and insomnia (14% [99/731]) were the most common. Modest increases were observed in vital sign measurements (blood pressure [3.6/2.3 mm Hg], heart rate [6.7 beats per minute]) across all patient groups; most of the changes occurred by month 3. Improvements from baseline in efficacy assessments started at month 1 and were maintained throughout the study.

CONCLUSIONS

Armodafinil remained effective and was generally well tolerated. Increased monitoring of blood pressure may be appropriate in patients on armodafinil. Armodafinil represents an option for long-term treatment of patients with ES associated with treated OSA, SWD, or narcolepsy.

Tolerability and efficacy of armodafinil in naïve patients with excessive sleepiness associated with obstructive sleep apnea, shift work disorder, or narcolepsy: a 12-month, open-label, flexible-dose study with an extension period

STUDY OBJECTIVES

This 12-month, open-label, flexible-dose study with an extension period evaluated the tolerability and efficacy of armodafinil in patients with excessive sleepiness associated with treated obstructive sleep apnea (OSA), shift work disorder (SWD), or narcolepsy.

METHODS

Armodafinil-naïve, adult patients with excessive sleepiness associated with treated OSA (n = 170), SWD (n = 108), or narcolepsy (n = 50) received armodafinil (100-250 mg) once daily (treated OSA or narcolepsy) or before night shifts (SWD). Patients with OSA were regular users of continuous positive airway pressure (CPAP) therapy. Efficacy measures included the Clinical Global Impression of Improvement (CGI-I) and the Epworth Sleepiness Scale (ESS).

RESULTS

Across the diagnosis groups, the most commonly occurring adverse event was headache (14%-24%). Forty-three patients (13%) and 13 patients (4%) were withdrawn because of adverse events and insufficient efficacy, respectively. Armodafinil did not adversely affect CPAP therapy. At the final visit, 80% (95% CI: 74.1, 86.7) of patients with treated OSA and 84% (72.7, 94.8) of patients with narcolepsy were rated on the CGI-I as at least minimally improved with regard to overall clinical condition; 98% (95.2, 100.0) of patients with SWD were rated as improved with regard to sleepiness during night shifts, including the commute to and from work. Armodafinil improved ESS total scores in patients with treated OSA (mean [SD] [95% CI] change from baseline, -7.3 [5.6] [-8.39, -6.30]) and patients with narcolepsy (-4.7 [6.0] [-7.41, -1.93]).

CONCLUSIONS

Armodafinil administered for 12 months or more was generally well tolerated and improved wakefulness in patients with excessive sleepiness associated with treated OSA, SWD, or narcolepsy. Armodafinil improved the overall clinical condition of patients with treated OSA or narcolepsy.