The FDA has approved Orzeyful, the first drug to address the underlying mechanism of narcolepsy type 1.

On August 5, 2026, the U.S. Food and Drug Administration approved Orzeyful, or oveporexton, for the treatment of narcolepsy type 1 in adults. The FDA calls it the first drug approved to address the full spectrum of symptoms of this disorder and the first to directly restore impaired orexin signaling.

This fundamentally distinguishes oveporexton from most previously used medications. Stimulants primarily reduce daytime sleepiness, while anticataplexy or nighttime medications address other specific manifestations of the disease. Oveporexton acts on the orexin receptor type 2 and attempts to compensate for the neurochemical deficit underlying narcolepsy type 1.

A total of 273 participants participated in two randomized phase III trials, FirstLight and RadiantLight. After 12 weeks, oveporexton significantly increased wakefulness, reduced subjective daytime sleepiness, and reduced the frequency of cataplexy attacks. At a dose of 2 milligrams twice daily, the difference compared to placebo in the Maintenance of Wakefulness Test reached 19.16 minutes, and the Epworth Sleepiness Scale score improved by almost 10 additional points.

The drug also addressed symptoms typically considered outside the scope of "daytime sleepiness": sleep paralysis, hallucinations when falling asleep or waking up, sleep disturbances at night, and the overall impact of the disease on daily life. This formed the basis for the FDA's unusual formulation—treatment of narcolepsy type 1 "as a single disorder," rather than several individual symptoms.

What is narcolepsy type 1?

Narcolepsy type I is a chronic neurological disorder characterized by severe daytime sleepiness and bouts of cataplexy. Cataplexy is a sudden loss of muscle tone, often triggered by strong emotions such as laughter, surprise, or joy. Consciousness is usually preserved.

In addition to cataplexy and drowsiness, the condition can be accompanied by sleep paralysis, vivid dream-like hallucinations during the transition between sleep and wakefulness, and unusually fragmented nocturnal sleep. Thus, a person may constantly want to sleep during the day, but have poor and inconsistent sleep at night.

The primary biological cause of the disease is believed to be the loss of hypothalamic neurons that produce orexin, also known as hypocretin. The orexin system helps the brain stabilize wakefulness, regulates transitions between sleep and wakefulness, and is involved in controlling muscle tone. With a significant orexin deficiency, the boundaries between these states become unstable.

According to the FDA, narcolepsy type 1 affects approximately one in 2,000 people in the United States. The condition is lifelong: regeneration of damaged orexin neurons is currently impossible with existing treatments, so therapy is aimed at compensating for the impaired nervous system.

Manifestation of narcolepsy type I	What's happening
Excessive daytime sleepiness	It is difficult for a person to stay awake and concentrated
Cataplexy	A sudden decrease in muscle tone due to emotions
Sleep paralysis	When falling asleep or waking up, a person is temporarily unable to move
Hallucinations	Vivid images appear on the border between sleep and wakefulness
Disturbed night sleep	Sleep becomes fragmented, and frequent awakenings occur.
The main biological problem	Severe orexin signaling deficiency

The clinical characteristics of the disease and the mechanism of orexin deficiency are supported by FDA and ovporexton studies.

How Orzeyful differs from previous treatments

Before the advent of oveporextone, narcolepsy treatment was primarily focused on managing individual symptoms. Daytime sleepiness was treated with wakefulness-promoting medications, while cataplexy and nocturnal sleep disturbances could be addressed with other medication classes. As a result, a single patient sometimes had to simultaneously address several different manifestations of the disease.

Oveporexton represents a completely new approach. It is a selective agonist of the orexin receptor type 2 (OX2R). In other words, the molecule binds to the receptor normally activated by natural orexin, and activates it even when the brain's own orexin is deficient.

The drug does not restore lost orexin neurons or force the brain to synthesize normal amounts of orexin. Therefore, it is incorrect to talk about a cure for narcolepsy. Rather, oveporexton functions as a pharmacological signal substitute: the natural neurotransmitter is in short supply, but its receptor can be activated by the drug.

This is why the FDA emphasizes the distinction of the new drug from symptomatic therapy. Theoretically, restoring central orexin signaling could simultaneously impact wakefulness, cataplexy, REM sleep, and the stability of sleep-wake transitions. Results from Phase III studies have indeed shown improvements in several of these areas.

Approach	The main goal
Common stimulants and wakefulness enhancers	Reduce daytime sleepiness
Anti-cataplexy medications	Reduce the frequency of episodes of loss of muscle tone
Means for normalizing night sleep	Improve sleep structure and continuity
Oveporexton	Compensate for insufficient orexin signaling via OX2R
Can Oveporexton Regenerate Dead Neurons?	No
Is the drug a complete cure?	No
The main difference	By influencing the disease mechanism, it is possible to simultaneously influence several groups of symptoms.

How the drug's effectiveness was tested

The registration was based on two international, randomized, double-blind, placebo-controlled Phase III studies—FirstLight and RadiantLight. FirstLight enrolled 168 participants, while RadiantLight enrolled 105. Thus, the total randomized sample size was 273 participants.

Participants ranged in age from 16 to 70, but FDA approval only applies to adults; the drug's safety and efficacy in patients under 18 have not yet been established in the US. Eligibility required confirmation of narcolepsy type 1, severe daytime sleepiness, and at least four partial or complete cataplexy attacks per week.

FirstLight included ovepoxetine groups at 1 and 2 milligrams twice daily and a placebo. RadiantLight tested 2 milligrams twice daily against placebo. Doses were taken at least three hours apart. The placebo-controlled portion lasted 12 weeks, after which most participants who completed the study entered the long-term follow-up program.

The primary efficacy endpoint was the Maintenance of Wakefulness Test. Subjects are placed in calm, unstimulating conditions and tested for how long they can remain awake. Additional assessments included the Epworth Sleepiness Scale, frequency of cataplexy, severity of all narcolepsy symptoms, cognitive functioning, nocturnal sleep, and quality of life.

Characteristics of the research	Data
Research	FirstLight and RadiantLight
Phase	III
Design	Randomized, double-blind, placebo-controlled
Total number of participants	273
FirstLight	168 people
RadiantLight	105 people
Age of participants	16-70 years old
Duration of the main phase	12 weeks
Dose 2 mg	Twice a day
Main endpoint	Maintenance of Wakefulness Test
Additional indicators	Drowsiness, cataplexy, overall symptom severity, sleep, cognitive function, quality of life

The ability to stay awake has improved dramatically

Before treatment, the study participants were extremely sleepy. The average duration of wakefulness in the maintenance of wakefulness test was only about 4.8 minutes. This means that in a calm environment, many patients quickly fell asleep despite their best efforts to stay awake.

After 12 weeks, the 2-milligram dose of oveporexton twice daily resulted in a 19.16-minute improvement compared to placebo. For the 1-milligram group, the difference was 15.90 minutes. Both estimates were highly statistically significant.

From a practical standpoint, the effect was significant enough to bring a significant proportion of patients closer to the wakefulness range typical of people without severe pathological sleepiness. Data presented by the developer showed that most patients receiving 2 milligrams twice daily achieved a wakefulness test lasting at least 20 minutes.

However, the test does not mean that a person has completely recovered from the disease or is guaranteed to be able to safely drive, work at night, or perform potentially hazardous work. It is a standardized laboratory indicator of wakefulness that must be considered in conjunction with the subjective symptoms and functional capabilities of the individual.

Subjective sleepiness was also significantly reduced.

Efficacy was also assessed using the Epworth Sleepiness Scale. It includes eight daily life situations—for example, reading, watching television, or riding a passenger—and assesses the likelihood of unintentional sleepiness. The higher the score, the more severe the daytime sleepiness.

Before treatment, the average participant score was approximately 18.1 points, corresponding to severe sleepiness. After 12 weeks, the 2-milligram twice-daily dose resulted in a 9.71-point reduction compared to placebo. For the 1-milligram dose, the corresponding difference was 8.27 points.

Thus, the objective lab test and the patients' subjective assessments moved in the same direction. This is important, as the drug could theoretically improve the lab test result but make little difference in real-life outcomes. In this case, people simultaneously reported a significantly reduced tendency to fall asleep.

Additional analyses revealed improvements in daily functioning: fatigue, cognitive functioning, social activities, and performance of routine tasks and responsibilities. Across all six domains of the Functional Impacts of Narcolepsy scale, oveporexton was statistically and clinically superior to placebo.

Key indicator	Before treatment	Effect of oveporextone 2 mg twice daily relative to placebo
Average wake time in the MWT test	4.8 min	+19.16 min
Epworth Sleepiness Scale	18.1 points	-9.71 points
Cataplexy	Median 26 episodes per week	Frequency ratio 0.32
P value for main effects	-	<0.001
General daily function	Significantly disrupted	Improved in all areas studied

For the incidence of cataplexy, a rate ratio of 0.32 implies an approximately 68% lower incidence relative to placebo in the statistical model, rather than a guaranteed reduction of exactly 68% in every patient.

Cataplexy has become much less common.

Before treatment, the median frequency of cataplexy in participants in the two studies was approximately 26 attacks per week. This highlights the severity of the condition in the study group: some people experienced multiple episodes of sudden weakness within a single day.

At a dose of 2 milligrams twice daily, the rate ratio of cataplexy compared with placebo was 0.32, with a 95% confidence interval of 0.23 to 0.45. This corresponds to an approximately 68% relative reduction in the frequency of episodes compared with placebo.

Interestingly, the drug simultaneously increased wakefulness and reduced cataplexy. While traditional approaches may require different drug mechanisms to address these two issues, the orexin system is involved in regulating both functions. Therefore, restoring OX2R signaling could theoretically simultaneously stabilize wakefulness and muscle tone.

However, seizures did not disappear in all participants, and the FDA does not claim that oveporexton completely eliminates cataplexy. The actual effect of an individual patient may differ from the average clinical trial result.

Improved sleep paralysis, hallucinations and nighttime sleep

Of particular interest are symptoms that are typically discussed much less frequently than daytime sleepiness and cataplexy. The researchers used a specialized narcolepsy severity scale that simultaneously assesses sleepiness, cataplexy, sleep paralysis, hallucinations, and disrupted nocturnal sleep.

At a dose of 2 milligrams twice daily, the overall disease severity score improved by 17.4 points more than with placebo. For a dose of 1 milligram, the difference was 14.8 points. In both cases, the probability of the observed difference being explained by chance was extremely low.

Before treatment, approximately two-thirds of participants described their condition as severe or very severe. After 12 weeks, only 3.7 percent of those receiving oveporexton gave this assessment, compared to 52.9 percent of those receiving placebo. According to physicians, the proportion of patients who remained severely, severely, or extremely ill was 2.7 percent and 77.1 percent, respectively.

At least "significant" or "very significant" improvement in their condition was self-reported by 87.8 percent of patients receiving oveporexton, compared to 18.6 percent in the placebo group. Physician assessments yielded similar results: 80.6 percent and 15.7 percent, respectively.

Overall disease severity after 12 weeks	Oveporexton	Placebo
Patients consider symptoms to be severe/very severe	3.7%	52.9%
The doctor assesses the condition as severely severe.	2.7%	77.1%
The patient reports significant/very significant improvement	87.8%	18.6%
The doctor reports significant/very significant improvement	80.6%	15.7%

The figures refer to the pooled data across ovporexton groups in the symptom severity analysis and do not represent the same response for each patient.

The drug altered the very structure of REM sleep.

Narcolepsy is closely associated with a disturbance in the regulation of rapid eye movement (REM) sleep. In patients, elements of REM sleep can "break through" into wakefulness: cataplexy resembles the physiological loss of muscle tone during REM sleep, while sleep paralysis and dream-like hallucinations are also associated with the unstable boundary between REM sleep and wakefulness.

Nocturnal polysomnography was used in phase III studies. After treatment with oveporextone, the time from sleep onset to the first REM sleep episode increased and the proportion of REM sleep in the first quarter of the night decreased. Pathological transitions to REM sleep, characteristic of narcolepsy, also decreased.

The overall proportion of REM sleep decreased by approximately 4.0-5.1 percentage points relative to placebo, while the proportion of stage II sleep increased. However, no significant changes were observed in deep stage III sleep. This suggests not simply a sedative effect, but a specific restructuring of the pathologically unstable sleep structure.

At the same time, hallucinations and sleep paralysis episodes were significantly reduced. At a dose of 2 milligrams twice daily, subjectively disturbed nocturnal sleep also improved. These results help explain why the FDA characterizes oveporexton as a drug capable of addressing a wide range of daytime and nighttime manifestations of the disease.

What side effects were found?

According to the FDA, the most common adverse reactions were insomnia, increased urination frequency, urinary urgency, and increased salivation. Most of these effects are biocompatible with activation of the orexin system, which affects more than just the sleep-wake centers.

In a pooled analysis of phase III studies, the most common adverse events were increased urination and insomnia. Only six participants discontinued treatment due to adverse events: three in the 1-milligram group, two in the 2-milligram group, and one in the placebo group.

This indicates acceptable tolerability over 12 weeks, but does not allow a full assessment of long-term safety. Narcolepsy is a lifelong condition, so the results of the ongoing extension studies, to which 250 of the 258 participants who completed the primary phase have entered, are particularly important.

The FDA also warns about drug interactions: Orzeyful should not be used concomitantly with strong CYP3A inhibitors. Before prescribing, inform your doctor of all medications you are currently taking. Safety and effectiveness in patients under 18 years of age have not yet been established in the United States.

Adverse event or limitation	What is known
Insomnia	One of the most common reactions
Frequent urination	Frequently observed in studies
Urgent urge to urinate	Listed by the FDA as one of the major side effects
Increased salivation	FDA approved
Discontinuation of therapy due to side effects	Low incidence in 12-week studies
Strong CYP3A inhibitors	Concomitant use is not recommended by the FDA.
Age under 18 in the United States	Safety and effectiveness have not been established.
Long-term safety	Continues to be studied

This is not a stimulant in the usual sense.

Although the drug increases wakefulness, its mechanism is fundamentally different from that of classic psychostimulants. Oveporexton was not designed to non-specifically enhance the activity of multiple neurotransmitter systems; it targets a specific orexin receptor associated with the pathological mechanism of narcolepsy type 1.

Because of this, the effect potentially extends beyond that of regular stimulation. The orexin system is involved not only in maintaining wakefulness but also in the stability of REM sleep and muscle tone. This may explain the simultaneous reduction in daytime sleepiness, cataplexy, sleep paralysis, and hallucinations.

However, the absence of a typical stimulant mechanism does not mean the absence of psychoactive effects or the need for control. The FDA has recommended oveporexton for inclusion under the US Controlled Substances Act. Until the US Drug Enforcement Administration's decision, the drug cannot legally enter the US market.

Thus, the FDA's approval on August 5th did not immediately mean the pills would be available in pharmacies. The next regulatory step is the DEA's decision on the drug's regulatory category, after which it will be legally available for sale in the US.

Why is approval considered a significant event?

Orzeyful's most significant feature is its shift from treating individual symptoms to pharmacologically replacing the missing neurochemical signal. In neurology, this is a rare example of a disease in which a specific neurotransmitter deficiency is known, and an oral medication has been developed that directly activates the corresponding receptor.

The results of Phase III are particularly noteworthy because improvements were detected by both objective and subjective measures. Participants remained awake longer in a laboratory test, self-reported less sleepiness, experienced cataplexy less frequently, and reported improved daily functioning.

Simultaneously, nocturnal manifestations of the disease and REM sleep structure changed. This supports the hypothesis that OX2R agonism addresses a fundamental instability in the sleep-wake system, rather than simply artificially forcing a person to remain active during the day.

However, the drug does not restore dead neurons and therefore cannot yet be considered a curative therapy. If treatment is discontinued, the orexin deficiency persists. Long-term observation programs will determine how sustainable the results will be with long-term daily use and whether the safety benefits will be maintained.

What remains unknown for now

The main question concerns long-term safety. The placebo-controlled Phase III trial lasted 12 weeks, while a person with narcolepsy would potentially need treatment for decades. Even a relatively large sample of 273 people cannot detect all rare side effects.

The cardiovascular, urinary, and neuropsychiatric effects of prolonged stimulation of the orexin system will require special attention. The very occurrence of insomnia in some participants demonstrates that the restoration of wakefulness can, with excessive pharmacological activity, turn into unwanted arousal.

The drug's effectiveness in children, people with narcolepsy type 2, and other conditions associated with pathological sleepiness is also unknown. The US approval applies specifically to adults with narcolepsy type 1. These results cannot be automatically generalized to idiopathic hypersomnia or common chronic sleepiness.

Finally, the Phase III trials were funded by Takeda Development Center Americas, the developer of oveporexton. A significant portion of the clinical trial authors are company employees. This is standard for the regulatory development of a new drug, but independent studies and post-registration data will be particularly important for the final assessment of efficacy and safety.

Research has already shown	Not yet established
Significant improvement in the ability to stay awake	Safe to use for decades
Reduction of subjective daytime sleepiness	Efficacy in children under 18 years of age in the United States
Significant reduction in cataplexy	Efficacy in narcolepsy type 2
Reduction of sleep paralysis and hallucinations	Possibility of restoration of dead orexin neurons
Improved nighttime REM performance	Will the need for all other drugs disappear for every patient?
Improving daily functioning	Rare adverse effects after mass use
Impact on the orexin mechanism of the disease	Complete cure of the disease

Results

The FDA approved Orzeyful on August 5, 2026, as the first drug designed to treat narcolepsy type 1 through direct restoration of orexin signaling. The drug is an orally administered, selective orexin receptor type 2 agonist and is taken twice daily.

In two phase III studies involving 273 participants, oveporexton was significantly superior to placebo in objective alertness, subjective daytime sleepiness, and cataplexy frequency. At a dose of 2 milligrams twice daily, the benefit on the Maintenance of Wakefulness Test reached 19.16 minutes, and on the Epworth Sleepiness Scale, it was 9.71 points.

Additional analyses revealed improvements in sleep paralysis, hallucinations, nocturnal sleep, and cognitive and daily functioning. Therefore, the approval decision has broader implications than the introduction of yet another "anti-drowsiness" drug: for the first time, drug therapy targets the neurobiological mechanism underlying the main symptoms of narcolepsy type 1.

However, Orzeyful does not restore orexin neurons or cure the disease. Its long-term safety is still being studied, the drug is FDA-approved only for adults, and its availability in the US is pending the DEA's approval of its status under the Controlled Substances Act.

News sources

Main news source: US Food and Drug Administration. FDA Approves First Drug to Treat the Full Range of Narcolepsy Type 1 Symptoms. FDA News Release, August 5, 2026. FDA Press Release.

The Phase III scientific data were published as a peer-reviewed congress supplement in the journal SLEEP:

Mignot E, Dauvilliers Y, Del Rio Villegas R, et al. Efficacy and Safety of Oveporexton (TAK-861), an Oral Orexin Receptor 2 Agonist, for Narcolepsy Type 1 Treatment: A Pooled Analysis of Phase 3 Studies. Sleep. 2026;49(Suppl 1):A328-A329.
DOI: 10.1093/sleep/zsag091.0736.

Additional Phase III publication across the full spectrum of symptoms:

Dauvilliers Y, Arnulf I, Barateau L, et al. Effect of Oveporexton (TAK-861), an Oral Orexin Receptor 2 Agonist, on Narcolepsy Type 1 Symptom Severity: A Pooled Analysis of Two Phase 3 Studies. Sleep. 2026;49(Suppl 1):A327.
DOI: 10.1093/sleep/zsag091.0732.

Additional publication on nighttime sleep:

Barateau L, Gong Y, Dauvilliers Y, et al. Effects of Treatment with Oveporexton, an Orexin Receptor 2 Agonist, on Sleep in People with Narcolepsy Type 1: Phase 3 Results. Sleep. 2026;49(Suppl 1):A322.
DOI: 10.1093/sleep/zsag091.0722.

A previous full-scale Phase II study was published in The New England Journal of Medicine:

Dauvilliers Y, Plazzi G, Mignot E, et al. Oveporexton, an Oral Orexin Receptor 2-Selective Agonist, in Narcolepsy Type 1. N Engl J Med. 2025;392:1905-1916.
DOI: 10.1056/NEJMoa2405847.

Phase III studies: FirstLight - NCT06470828; RadiantLight - NCT06505031.