The U.S. Food and Drug Administration approved Orzeyful (oveporexton) on August 5, 2026, for the treatment of narcolepsy type 1 in adults. It is the first drug approved for narcolepsy type 1 as a complete disorder, and the first to work by directly restoring the signaling system whose loss causes the disease.
What is narcolepsy type 1?
Narcolepsy type 1 is a rare, lifelong neurological disorder affecting an estimated 1 in 2,000 people in the United States. Its defining feature is a nearly complete destruction of a small population of brain cells in the lateral hypothalamus that produce orexin, a neuropeptide that regulates wakefulness, sleep transitions, and muscle tone. Postmortem analyses have found losses of up to 95% of these orexin-producing neurons in people with the condition. The cause of this neuronal loss is not fully established, but evidence strongly points to autoimmune destruction: over 90% of people with narcolepsy type 1 carry the HLA-DQB1*06:02 allele, a genetic marker associated with an odds ratio exceeding 250 for the disease.
Without orexin, the brain loses its ability to maintain stable wakefulness or regulate the boundary between sleep and waking. The result is a cluster of disabling symptoms that extend across the full 24-hour cycle. Excessive daytime sleepiness is universal. Cataplexy, sudden brief episodes of muscle weakness or paralysis triggered by strong emotions such as laughter, is the hallmark symptom that defines type 1 and distinguishes it from narcolepsy type 2. Additional symptoms include sleep paralysis, hypnagogic and hypnopompic hallucinations, severely disrupted nighttime sleep, and cognitive difficulties affecting attention, memory, and executive function. Symptoms typically emerge between the ages of 15 and 30 and persist for life.
The gap in existing treatment
Until this approval, narcolepsy type 1 treatment was organized around individual symptom management. Stimulants such as modafinil and amphetamine salts were used to promote daytime wakefulness. Sodium oxybate and its low-sodium formulation addressed cataplexy and nighttime sleep disruption but require nighttime dosing and carry significant prescribing restrictions. No approved drug acted on the orexin system. None had been approved for narcolepsy type 1 as a unified disorder evaluated across its full symptom range.
How oveporexton works
Oveporexton is a selective orexin receptor 2 (OX2R) agonist. Rather than stimulating wakefulness through a secondary pathway, it directly activates the same brain receptor that the body’s own orexin would normally stimulate, substituting for the missing signal at its intended target. The drug is taken as an oral tablet twice daily.
Orexin acts through two receptor subtypes, OX1R and OX2R. Evidence indicates that OX2R is the primary receptor responsible for promoting wakefulness and suppressing inappropriate intrusions of rapid eye movement (REM) sleep, the neurological basis of cataplexy and related symptoms. By selectively targeting OX2R, oveporexton addresses both daytime and nighttime aspects of the disorder at the same root mechanism.
What the clinical trials showed
The FDA based its approval on two randomized, double-blind, placebo-controlled 12-week trials enrolling 273 adults with narcolepsy type 1. The FirstLight study (NCT06470828) enrolled 168 participants across three arms: oveporexton 2 mg twice daily, 1 mg twice daily, and placebo. The RadiantLight study (NCT06505031) enrolled 105 participants across two arms: oveporexton 2 mg twice daily and placebo. Both studies were conducted across 19 countries.
Across both trials, participants taking oveporexton 2 mg showed significant improvements in their ability to remain awake during the day, measured by mean sleep latency on the Maintenance of Wakefulness Test. Participants also reported substantially less daytime sleepiness and a significant reduction in weekly cataplexy episodes compared with placebo. On the Functional Impacts of Narcolepsy Instrument Cognitive Function domain, approximately 70% of patients across all doses reported no significant cognitive difficulties, compared to approximately 15% in the placebo arm. Hallucinations and sleep paralysis were largely resolved, REM sleep patterns shifted toward those seen in healthy controls, and more than 95% of participants who completed the 12-week studies enrolled in an ongoing long-term extension study.
The phase 2 program was published in the New England Journal of Medicine in May 2025. In that 8-week trial, oveporexton produced improvements in average sleep latency on the Maintenance of Wakefulness Test ranging from 12.5 to 25.4 minutes across dose arms, versus a decline of 1.2 minutes in the placebo group (adjusted p≤0.001 for all comparisons), a substantial improvement relative to the 2-to-12-minute range typically seen with currently approved therapies.
Emmanuel Mignot, M.D., Ph.D., principal investigator for the FirstLight Phase 3 study, said at the time of the Phase 3 data presentation at SLEEP 2026: “Narcolepsy type 1 is a 24-hour disease driven by orexin deficiency, and while excessive daytime sleepiness and cataplexy are the most recognized symptoms, many people experience additional bothersome symptoms such as cognitive difficulties and disrupted nighttime sleep. Oveporexton has demonstrated significant improvement across a broad range of NT1 symptoms, daily functioning and quality of life with the potential to shift disease management beyond incremental symptom relief.”
Safety and prescribing considerations
The most common side effects were insomnia, increased urinary frequency, urgency to urinate, and increased saliva production. The rate of participants stopping treatment because of side effects was low. Oveporexton should not be used with strong CYP3A inhibitors, a class that includes certain antifungals, some HIV medications, and clarithromycin. Safety and effectiveness in patients under 18 years of age have not been established.
The drug received both Breakthrough Therapy Designation and Priority Review from the FDA. Breakthrough Therapy Designation is granted when early clinical evidence shows substantial improvement over existing therapies for serious conditions. Priority Review is reserved for drugs that could offer significant improvements in treating serious conditions.
One immediate constraint on availability: oveporexton has been recommended for scheduling under the Controlled Substances Act and cannot be legally marketed until the Drug Enforcement Administration issues a scheduling decision, a process that typically takes several months after FDA approval.
What this approval means
For a condition whose treatment landscape had been largely static, this approval represents a genuine mechanistic shift. Existing treatments manage symptoms through pathways unrelated to orexin. Oveporexton addresses the deficit at the point where it originates. The FDA approval for narcolepsy type 1 as a complete disorder, rather than for individual symptoms separately, reflects both the trial design and the underlying logic of targeting a single root cause across its full range of consequences. Orzeyful was approved for Takeda Pharmaceuticals America, Inc. China approved oveporexton on July 22, 2026, under the same brand name. A regulatory submission is under review in Japan.
- U.S. Food and Drug Administration. FDA Approves First Drug to Treat the Full Range of Narcolepsy Type 1 Symptoms. August 5, 2026. FDA press announcement.
- Dauvilliers Y, et al. Oveporexton, an Oral Orexin Receptor 2-Selective Agonist, in Narcolepsy Type 1. New England Journal of Medicine. 2025;392(19):1905-1916. doi:10.1056/NEJMoa2405847.
- Takeda Pharmaceutical Company. FDA Approves ORZEYFUL (oveporexton) for Adults with Narcolepsy Type 1. August 5, 2026. Takeda press release.
- Rauf A, et al. Orexin Deficiency in Narcolepsy: Molecular Mechanisms, Clinical Phenotypes, and Emerging Therapeutic Frontiers. Brain and Behavior. 2025. doi:10.1002/brb3.70984.
- Arif Z, et al. Orexin receptor 2 agonists: a pathophysiologic approach to narcolepsy type 1. Annals of Medicine and Surgery. 2025. doi:10.1097/MS9.0000000000004476.