Effectiveness and treatment optimization among participants with narcolepsy switching from sodium oxybate to lower-sodium oxybate: interim data from the segue study

Abstract Introduction Lower-sodium oxybate (LXB) contains 92% less sodium than sodium oxybate (SXB) and is approved for treating cataplexy or excessive daytime sleepiness in patients with narcolepsy (≥7 years of age) and for treating idiopathic hypersomnia in adults. The SEGUE study examines safety, tolerability, effectiveness, and treatment optimization in participants with narcolepsy transitioning from SXB to LXB. Methods Eligible participants in this ongoing, multicenter, open-label study are adults with narcolepsy type 1 or 2 who are on a stable dose (maximum 9 g/night; no single dose >6 g) and regimen (once, twice, or thrice nightly) of SXB. After 2 weeks on a stable SXB dose/regimen (baseline period), participants switch to the same dose/regimen of LXB (intervention period; 6 weeks). If needed, LXB dose/regimen is titrated to optimize efficacy/tolerability. Assessments include the Patient Global Impression of Change (PGIc), a forced preference questionnaire (FPQ), and an ease of switching medication scale (EOSMS; all collected at end of treatment/early discontinuation). An interim analysis (first 24 participants to complete the study) is reported. Results A majority of participants were female (54%) and White (92%); mean (SD) age was 45.5 (16.20) years. Starting and ending (end of treatment/early discontinuation) median total nightly doses of LXB were both 9.0 g. Most participants took LXB twice nightly (88% at both time points). Twenty-two participants completed the transition period; mean (SD) time to optimized dose was 1.4 (1.56) days, and median (range) number of changes in dose/regimen was 0.0 (0, 1). At end of treatment/early discontinuation, most participants reported improvement (very much/much/minimal; 57%) or no change (43%) in narcolepsy symptoms on the PGIc, preferred LXB over SXB on the FPQ (86%), and reported that the transition to LXB was easy (easy/extremely easy/not difficult at all) on the EOSMS (91%). Conclusion Participants with narcolepsy switched from SXB to LXB with minimal modifications of dose/regimen and reported that the transition process was easy. Efficacy of oxybate treatment was maintained or improved, and most participants preferred LXB over SXB. Support (If Any) Jazz Pharmaceuticals.