Neurochemical perspectives of the narcoleptic syndrome

Narcolepsy has been defined as a disorder of excessive sleep often associated with cataplexy, sleep paralysis and hypnagogic hallucinations. Although the pathophysiology of the narcoleptic syndrome is not well understood, derangement in the functions of CNS catecholamines and serotonin (5-HT) have been implicated. In the present paper we summarize evidence to suggest a role for the endogenous opioids in the regulation of normal sleep and in the pathophysiology of the narcoleptic syndrome.

Successful treatment of idiopathic hypersomnia and narcolepsy with modafinil

1. Modafinil, a putative central alpha 1 adrenergic agonist, was tested in idiopathic hypersomnia and narcolepsy. 2. Sleep attacks and drowsiness were significantly decreased in 83% of 18 hypersomniac subjects and 71% of 24 narcoleptics. 3. When cataplectic episodes were not totally suppressed the association of a low dose of Clomipramine was successful in improving them. 4. Modafinil, used for at least 3 years in some patients, produces, in most cases, no peripheric sides effects, does not disturb night sleep and is never responsible of tolerance of drug dependence.

Narcolepsy. Diagnosis, treatment, and management

Narcolepsy is a syndrome of unknown origin characterized by the irresistible urge to sleep. Other important features are disturbed nocturnal sleep and abnormal manifestations of REM sleep such as cataplexy, sleep paralysis, and abnormal sleep-onset REM periods. Narcolepsy is not a rare condition. With a prevalence between 2 and 10 per 10,000 individuals, it is about as common as multiple sclerosis. Like multiple sclerosis, narcolepsy can be disabling and have profound consequences for job capability, public safety, sense of self-worth, and social image.

Selegiline in narcolepsy

We examined the effect of the specific monoamine oxidase-B (MAO-B) inhibitor selegiline (deprenyl, Eldepryl), 20-30 mg p.o. daily, in 21 subjects with the narcoleptic syndrome for 4 weeks. Selegiline was compared to no treatment (7 subjects) or conventional central stimulant drugs, including dexamphetamine or mazindol (14 subjects). Severity and frequency of narcolepsy, accessory symptoms, and effects of selegiline on mood were measured. Selegiline, as well as causing MAO-B inhibition, is interconverted to amphetamine. Urinary amphetamine and methamphetamine excretion were determined in 18 subjects after 4 weeks on selegiline and the results were compared with amphetamine excretion in subjects on dexamphetamine. The effect of selegiline, 20-30 mg p.o., on alertness and mood was similar to that of dexamphetamine in the same dosage, with comparable sympathomimetic side effects. Selegiline, 20 mg p.o., caused a subjective increase in alertness for 4-8 h. Mean urinary amphetamine excretion on dexamphetamine, 15-70 mg daily (mean 29 mg) at pH 5.6-6.6, was 5,184 micrograms/24 h, and on selegiline, 20-30 mg daily (mean 22.5), was 4,127 micrograms/24 h. We conclude that selegiline, 20-30 mg daily, requires further evaluation in narcolepsy.

Ophthalmic manifestations of narcolepsy

We reviewed the records of 755 patients in whom narcolepsy was diagnosed between 1979 and 1983. In a subset of 405 previously undiagnosed and untreated patients, the following variables were assessed: the subspecialty in which the condition was diagnosed, age and sex of the patients, family history, expressed symptoms in the total group, symptoms in patients whose condition was diagnosed by ophthalmologists, laboratory aids used for diagnosis, treatment, and outcome.

Effect of L-dopa on periodic movements in sleep in narcolepsy

Five narcoleptic patients presenting periodic movements in sleep were investigated during treatment with L-dopa administered together with a decarboxylase inhibitor. One of these patients was also treated with gamma-hydroxybutyrate and zimelidine, and recorded at the sleep laboratory under each condition. L-dopa was effective in controlling periodic movements in sleep in all patients, but gamma-hydroxybutyrate or zimelidine were not. These results are discussed in view of a dopaminergic implication in the pathogenesis of periodic movements in sleep.

The treatment of accessory symptoms in narcolepsy: a double-blind cross-over study of a selective serotonin re-uptake inhibitor (femoxetine) versus placebo

A randomized, double-blind cross-over trial was carried out in 10 patients with narcolepsy to evaluate the effect of 600 mg femoxetine versus placebo. In comparison to placebo, femoxetine treatment resulted in a significant decrease in both the number and severity score of cataplectic attacks per day. There were also significantly fewer attacks of sleep paralysis, whilst the effects on nightmare and hypnogenic hallucinations were minor. The frequency of sleep attacks decreased slightly during femoxetine treatment, but the overall estimated sleep time during the day and excessive daytime sleepiness remained un-affected. An ambulatory sleep recording for 48 h one week after the start of the femoxetine and placebo period showed that femoxetine treatment resulted in a significant decrease in the total time spent in REM sleep. The side-effects of femoxetine were restricted to transient nausea in 2 patients. It is concluded that femoxetine or other selective serotonin reuptake inhibitors may be a useful alternative for narcoleptic patients who experience troublesome side-effects with tricyclic antidepressants.

[Value of mazindol in Gélineau's disease. Apropos of 10 cases]

Ten narcoleptic patients were treated daily with Mazindol 2-6 mg for 42.2 months (31-63 months). The response was excellent on narcoleptic attacks in 6 and on cataplexy in 7 cases. However, the nocturnal sleep disturbance persisted unchanged. The improvement was poor in 1 case and inexistant in 1 subject. Minor side effects (dry mouth) occurred in 3 cases, and urinary retention obliged to stop the medication in 2 cases.

Antidepressants: their uses in nonpsychiatric disorders of aging

Antidepressants are recommended by some clinicians as therapy for irritable colon even when there is no evidence of clinical depression, since this syndrome may represent a type of chronic masked depression. Antidepressants may be a good alternative in elderly patients with peptic ulcer disease, particularly in those with concurrent depression. Advantages include once-a-day administration, lower cost, and ease of serum monitoring.

Fenetylline: therapeutic use, misuse and/or abuse

Fenetylline (CAPTAGON) is included in a list of compounds to be considered by a World Health Organization (WHO) Expert Committee in April 1985 for possible international scheduling under the Convention on Psychotropic Substances, 1971. For over 23 years, this central stimulant has been used therapeutically in hyperkinetic children and other indications in place of amphetamines and other central stimulants with higher risk levels. In good correspondence with recent animal data fenetylline also shows significant qualitative and quantitative differences compared to amphetamine in man. It has few adverse side effects, a lower abuse potential and little actual abuse compared to amphetamine. Thus its benefit/risk assessment is substantially more favourable than that of other central stimulants. For proper therapeutic use of the substance, prescription status is or should be required by national authorities.

Narcolepsy/cataplexy. III: Nocturnal sleep and wakefulness patterns

Nocturnal sleep and wakefulness patterns of 50 patients with narcolepsy and cataplexy were compared to those of 50 control subjects. A sleep onset REM period (SOREM) occurred in 22 (44%) of the patients but in none of the controls. Comparisons among patients showing a SOREM, patients without this abnormality, and controls demonstrated that the timing, number and duration of the remaining REM periods did not differ across the three groups. Thus, the basic REM sleep disturbance in narcolepsy appears to relate to the timing of onset of the initial REM period. This finding lends further support to the theory of dual control of REM-NREM cycling. While narcoleptics took significantly less time to fall asleep, they had significantly more awakenings, wake time after sleep onset and total wake time. The disturbed sleep experienced by patients could not be accounted for by the presence of a sleep onset REM period or the use of medication. Nocturnal wakefulness appeared to be distributed in a regular oscillating manner throughout the recording period similar to the pattern of daytime vigilance previously reported in normal subjects. Thus, typical nocturnal dampening of daytime ultradian vigilance rhythms may be lost in the narcoleptic patient.

Therapeutic effects of mazindol on narcolepsy

Mazindol, a new anorexiant, was administered at a daily dose of 0.5-4 mg to 10 narcoleptic subjects aged 21-63 years. All the patients suffered from sleep attacks and one or more of the REM-related symptoms. Eight patients received only mazindol, and two patients received mazindol simultaneously with clomipramine or flurazepam. Sleep attacks were reduced in nine patients, and cataplexy was also markedly reduced in four patients. Mild adverse reactions were reported in six patients: two patients complained of headache, four of nocturnal sleep disturbance, and two of reduced appetite. Most side effects disappeared spontaneously or after dose reduction, and none of the patients had to stop medication. The results suggest that mazindol is effective not only for sleep attacks but also for cataplexy. It is recommended as a treatment for mild cases of narcolepsy.

Treatment of narcolepsy with codeine

The effectiveness of codeine as a treatment for the excessive daytime sleepiness of narcolepsy was studied in two experimental trials. In an open trial of codeine in five narcoleptic subjects, dramatic clinical improvement was reported. However, all-night polysomnography and maintenance of wakefulness tests before and after codeine showed no significant differences. A double-blind placebo-codeine trial was conducted in which eight narcoleptic subjects received codeine for 1 week and placebo for 1 week in a random order. During the week they kept a diary, and on the sixth evening and for 10 h following awakening on the seventh day they were monitored by radiotelemetry in the sleep laboratory for electroencephalogram, electro-oculogram, and electromyogram. The results were analyzed for sleep stages as well as four levels of wakefulness. The results showed no significant differences in any of the objective sleep or wakefulness parameters. However, the diaries showed significantly fewer naps during the week on codeine as compared with the placebo week. Eighteen of 27 narcoleptic patients treated with codeine report clinical improvement. Codeine consistently results in subjective clinical improvement. However, this is not reflected in the objective measures generally used to assess daytime sleepiness.

Treatment of narcolepsy: objective studies on methylphenidate, pemoline, and protriptyline

Methylphenidate, pemoline, and protriptyline were studied for their treatment efficacy in narcolepsy. A low, intermediate, and high dose level of each drug was studied for 1 week. For methylphenidate the doses were 10, 30, or 60 mg/day; for pemoline, 18.75, 56.25, or 112.5 mg/day; and for protriptyline 10, 30, or 60 mg/day. The order of dose levels was random from subject to subject and the daily dose was divided into thirds and taken in identically appearing capsules morning, noon, and afternoon. Subjects were 6 narcoleptic patients studied on methylphenidate (5 women and 1 man; mean age 54.5 + 11.7 years), 7 narcoleptic patients studied on pemoline (5 women and 2 men; mean age 43.0 + 7.1 years), and 4 narcoleptic patients studied on protriptyline (2 women and 2 men; mean age 42.5 + 16.9 years). Testing consisted of day-long sessions occurring at the end of each dose level and involving a clinical status questionnaire as well as maintenance of wakefulness, Wilkinson addition, and Digit-Symbol Substitution tests. Results were compared with 9 control subjects with no sleep disorder (5 women and 4 men; mean age 39.2 + 8.4 years) who were given placebo that was purported to be a "stimulant drug" and tested in a similar manner. Results demonstrated profound differences in ability to stay awake and perform between narcoleptic patients and controls. Data also suggested that methylphenidate significantly improves ability to stay awake. Pemoline seems to improve ability to perform. Protriptyline does not significantly alter ability to stay awake or to perform.

Treatment of narcolepsy with gamma-hydroxybutyrate. A review of clinical and sleep laboratory findings

Previous studies on the effects of gamma-hydroxybutyrate (GHB) on the sleep and clinical response of patients with narcolepsy are reviewed. New information on 48 patients treated with GHB for as long as 9 years is presented. These studies indicate that 2.25 to 3.00 g of GHB, taken in conjunction with a low dose of a stimulant during the day, rapidly alleviate the symptoms of narcolepsy in most patients. Tolerance does not develop to this treatment regimen; neither have any patients discontinued the treatment because of side effects. In poor responders, daytime drowsiness and not cataplexy has been the most common residual symptom. Sleep studies reveal that GHB induces REM followed by slow wave sleep. Although total sleep time at night may be unchanged, sleep is less fragmented. GHB appears to be effective because it can induce the symptoms of narcolepsy and contain them at night. It is noteworthy, therefore, that the central biochemical changes induced by GHB also appear comparable to those found naturally in narcolepsy.

Viloxazine hydrochloride in narcolepsy: a preliminary report

Twenty-three narcoleptic subjects participated in a single-blind drug study with placebo-viloxazine hydrochloride (100 mg/day). One woman discontinued the study because of nausea and headaches during the treatment period. The remaining 22 subjects were polygraphically monitored during baseline, The remaining 22 subjects were polygraphically monitored during baseline, placebo intake, viloxazine treatment, and placebo intake following 48 h of drug withdrawal. Symptoms and side effects were evaluated subjectively and objectively. Except for the subject who discontinued the study, viloxazine was well tolerated, particularly in elderly subjects. The drug had an inhibitory effect on REM sleep, cataplexy, and other auxiliary symptoms. While there is no objective evidence that it heightens alertness, patients reported fewer sleep attacks.

The effect of zimelidine, a serotonin-reuptake blocker, on cataplexy and daytime sleepiness of narcoleptic patients

Narcolepsy is a neurological syndrome characterized by two major symptoms: excessive daytime sleepiness and cataplexy. Pharmacological and biochemical evidence support the hypothesis that dopaminergic mechanisms are involved in excessive daytime sleepiness. The pathophysiology of cataplexy and the action mechanisms of anticataplectic agents remain controversial issues. Cataplexy is usually controlled by tricyclic antidepressants, but these drugs interact with several central monoamine systems and also exert an anticholinergic effect. In the present study, zimelidine, a selective serotonin reuptake inhibitor without anticholinergic activity, was administered to 11 narcoleptic patients for 1-16 months. Cataplexy improved markedly in all patients, while no changes could be documented on excessive daytime sleepiness, either by self-report or polysomnographic nap recording. These results confirm the hypothesis that hypersomnolence and cataplexy are subject to different control mechanisms; support a serotoninergic, but not a cholinergic, theory of cataplexy; and suggest that selective serotonin reuptake inhibitors may be the treatment of choice for cataplexy.

DSIP in sleep disturbances

The effects of DSIP on night sleep and on waking functions are demonstrated in double-blind studies in insomniacs, presenting influences of single dose treatments as well as of repeated injections. Moreover, a single case study describes the efficiency of DSIP on narcolepsy.

Effects of clonidine in narcolepsy

The antihypertensive drug clonidine was given in an open trial to two treatment-resistant (psychostimulants and tricyclic antidepressants) narcoleptic patients. When given acutely, clonidine suppressed REM sleep. However, patients became tolerant after repeated doses but did not lose the drug's beneficial clinical effects. This suggests that REM suppression may not be necessary for improvement in narcolepsy. Assessments of both clinical and polysomnographic variables before and after the trial indicate that clonidine may have a place in the treatment of some patients with narcolepsy.

The effects and effectiveness of gamma-hydroxybutyrate in patients with narcolepsy

Thirty patients with polysomnographically confirmed narcolepsy were treated with GHB (gamma-hydroxybutyrate) for up to 30 weeks. The number of nightly awakenings significantly decreased, while Stages 3 and 4 sleep substantially increased. The clinical symptoms of cataplexy, sleep paralysis, hypnogogic hallucinations, daily naps, and sleep attacks all showed significant improvements. Daytime sleepiness, while not completely eliminated, was controlled with lower doses of stimulant medication than patients were taking before the study. No patient developed tolerance to the drug, and no serious side effects were noted.

Propranolol: long-term treatment in narcolepsy-cataplexy

Forty-eight sequential narcoleptic patients were treated with propranolol (80-240 mg/day) for an average period of 18.4 months. Initially all patients received single drug therapy; after 10 days or longer, however, 50% of patients also received tricyclics or stimulants because propranolol alone did not sufficiently suppress the narcoleptic symptoms. Fifty percent of patients judged the initial effectiveness of propranolol on daytime sleepiness to be good to very good; in these patients the effects seemed comparable to that of pemoline. Within 6 months, however, the effectiveness started to decrease, and after 26 months only 8% (2 out of 24) of those patients taking the single drug were satisfied with propranolol therapy alone. Side effects included disturbed night sleep, decreased blood pressure, increased lethargy, allergic skin rash, and asthma; 58% of the patients dropped out of the study after 26 months. Vigilance tests during the first 4 months (16 patients) showed significant improvements in all test criteria, including a shorter reaction time. All-night polygraphic electroencephalogram recordings of 14 patients on the eighth and ninth day of medication showed that average total sleep time decreased by 5.7%, but other sleep characteristics did not change significantly.