Effectiveness and Optimization of Low-sodium Oxybate in Participants with Narcolepsy Switching from Sodium Oxybate: Final Data from the Substitution of Equal Grams of Uninterrupted Xyrem to Xywav (SEGUE) Study
Wayne Macfadden1, Eileen Leary2, Craig Pfister1, Douglas Fuller1
1Jazz Pharmaceuticals, 2Formerly Jazz Pharmaceuticals
Objective:
SEGUE examined safety, tolerability, effectiveness, and treatment optimization in participants with narcolepsy transitioning from sodium oxybate (SXB, Xyrem®) to low-sodium oxybate (LXB, Xywav®).
Background:
LXB contains 92% less sodium than high-sodium oxybates (SXB and fixed-dose, high-sodium oxybate [Lumryz™]) and is approved for treating cataplexy and/or excessive daytime sleepiness in patients with narcolepsy (≥7 years old) and idiopathic hypersomnia in adults.
Design/Methods:
Participants in this multicenter, open-label study were adults with narcolepsy type 1/2 on a stable SXB dose/regimen. After 2 weeks on a stable SXB dose/regimen, participants switched gram-per-gram to LXB for 6 weeks. If needed, LXB dose/regimen were titrated to optimize efficacy and tolerability. Assessments included Patient Global Impression of Change (PGIc), forced preference questionnaire (FPQ), ease of switching medication scale (EOSMS), and Epworth Sleepiness Scale (ESS), all collected at end of treatment or early discontinuation.
Results:
Sixty participants entered the intervention period; 62% female, 88% were White, and mean (SD) age was 43.9 (15.33) years. Starting and ending (end of treatment or early discontinuation) median total nightly doses of LXB were 8.5 and 9.0 g, respectively. Most participants took LXB twice nightly (93% at both time points). Fifty-six participants completed the transition; mean (SD) time to stable dose was 2.5 (4.82) days, and median (range) number of changes in dose/regimen was 0.0 (0, 1). Most participants reported improvement (very much/much/minimal; 45%) or no change (48%) in narcolepsy symptoms on the PGIc, 79% preferred LXB over SXB (FPQ), and 93% reported the transition to LXB was easy, extremely easy, or not difficult at all (EOSMS). Mean (SD) ESS change from baseline (n=55) was −0.7 (2.31).
Conclusions:
Most participants with narcolepsy switched from SXB to LXB with minimal modifications of dose/regimen and reported the transition process was easy. Effectiveness of oxybate treatment (ESS) was maintained after transition, and most preferred LXB over SXB.