Effectiveness and Optimization of Lower-Sodium Oxybate in Participants With Narcolepsy Switching From Sodium Oxybate: Interim Data from the Substitution of Equal Grams of Uninterrupted Xyrem to Xywav (SEGUE) Study

Abstract: Introduction: The SEGUE study examines safety, tolerability, effectiveness, and treatment optimization in participants with narcolepsy transitioning from sodium oxybate (SXB) to lower-sodium oxybate (LXB; 92% less sodium than SXB). Methods: Eligible participants in this ongoing, multicenter, open-label study (NCT04794491) are adults with narcolepsy (type 1 or 2) on an SXB stable dose (maximum 9 g/night; no single dose >6 g) and regimen. After 2 weeks on SXB (baseline period), participants switch to the same LXB dose/regimen (intervention period; 6 weeks). Assessments include the Patient Global Impression of Change (PGIc), forced preference questionnaire (FPQ), and ease of switching medication scale (EOSMS; all collected at end of treatment/early discontinuation). An interim analysis (first 24 completers) is reported. Results: Most participants were White (92%); 54% were female; 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%). 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 (57%) or no change (43%) in narcolepsy symptoms on the PGIc, preferred LXB over SXB on the FPQ (86%), and reported the transition was easy on the EOSMS (91%). Conclusions: Participants switched from SXB to LXB with minimal modifications and reported the transition was easy. Efficacy of oxybate treatment was maintained or improved, and most participants preferred LXB.Short Description: This interim analysis (first 24 participants to complete the SEGUE study) describes the effectiveness and treatment optimization of patients with narcolepsy transitioning from sodium oxybate (SXB) to lower-sodium oxybate (LXB). Treatment assessments included the Patient Global Impression of Change, a forced preference questionnaire, and an ease of switching medication scale. The findings demonstrate the ease of transitioning from SXB to LXB, with treatment effectiveness being maintained and most participants expressing a preference for LXB.Name of Sponsoring Organization(s): Jazz Pharmaceuticals