Real-World Results from TENOR Study Shed Light on Dosing Strategies When Switching to Low-Sodium Oxybate to Treat Narcolepsy

New data from a real-world study analyzed effectiveness, tolerability, and individualized dosing strategies in people with narcolepsy switching from sodium oxybate (Xyrem; Jazz Pharmaceuticals, Dublin, Ireland) to low-sodium oxybate (Xywav; Jazz Pharmaceuticals, Dublin, Ireland). The study results, which were presented at the World Sleep 2023 Congress, show that unequal dosing is most commonly used to help with falling asleep and to avoid morning grogginess.

The presented data was from the TENOR clinical trial (NCT04803786), which included 85 US adults with type 1 or 2 narcolepsy who were transitioning from Xyrem to Xywav. The following results were determined from patient diaries and questionnaires, as well as from reporting of physician-directed dosing strategies.

• Mean Epworth Sleepiness Scale (ESS) scores decreased throughout the transition from Xyrem to Xywav, with 59.5% and 75.0% of participants showing scores in the normal range at baseline and week 21, respectively.
• Mean Functional Outcomes of Sleep Questionnaire, short version (FOSQ10) and British Columbia Cognitive Complaints Inventory (BC-CCI) scores remained stable from baseline to week 21 (FOSQ-10: 14.4-15.2; BC-CCI: 6.1-5.0).
• Seventeen of the 85 participants (20%) took unequal doses of Xyrem or Xywav.
• Before transitioning to Xywav, 82 participants took twice nightly doses of Xyrem with 9 (11%) or 1 (1%) taking unequal doses of either a larger first dose or larger second dose, respectively.
• Immediately after transitioning to Xywav, 7 (9%) and 2 (2%) of these participants took a higher first or second dose, respectively.
• After the 21 weeks of the study period, 8 (21%) participants followed an unequal dosing strategy, each of whom took a higher first dose.  
• All recorded timings between doses were greater than 2.5 hours.
• Most common doses for Xyrem and Xywav were 7.5 and 9.0 g, respectively.

The most common reasons for the observed unequal dosing were to avoid morning grogginess (Xyrem: 44%; Xywav: 33%), to help with falling asleep (Xyrem: 25%; Xywav: 13%), and to improve sleep quality (Xyrem: 13%; Xywav: 29%). Side effect avoidance was also reported as a common reason for unequal dosing. The real-world insight gained by this study is intended to assist in future clinical decision making and to improve individualized dosing strategies for patients with narcolepsy.