Japan's Ministry of Health, Labour and Welfare (MHLW) has approved Orzeyful (oveporexton) for the treatment of narcolepsy type 1 (NT1) in adults, marking a major regulatory approval for Takeda's first-in-class oral orexin receptor 2 (OX2R) agonist. The drug, discovered in Takeda's Japanese laboratories, is the only medicine approved in Japan indicated to address the underlying orexin deficiency in NT1 rather than individual symptoms.
The MHLW approval covers oral oveporexton at a starting dose of 1 mg twice daily — taken upon awakening and again three to five hours later — with the option to increase to 2 mg twice daily if tolerated and additional efficacy is needed. Available as 0.5 mg, 1 mg, and 2 mg tablets, the drug selectively activates OX2Rs to restore orexin signaling, promoting wakefulness and suppressing abnormal rapid eye movement (REM)-sleep phenomena, including cataplexy.
The approval is supported by the global Phase III FirstLight (TAK-861-3001) and RadiantLight (TAK-861-3002) studies, which demonstrated statistically significant improvements across the full range of NT1 symptoms assessed — including excessive daytime sleepiness and cataplexy — compared to placebo. As previously reported, secondary and exploratory endpoint data from both studies further reinforced the breadth of symptom control. Oveporexton was generally well-tolerated; the most common adverse events were insomnia, urinary urgency, urinary frequency, and excessive saliva.