486 Timing and Duration of Adverse Events in a Clinical Trial of Lower-Sodium Oxybate in Participants With Narcolepsy With Cataplexy

Abstract

Abstract Introduction This analysis evaluated treatment-emergent adverse events (TEAEs) during a double-blind, placebo-controlled, randomized withdrawal trial (NCT03030599) of lower-sodium oxybate (LXB; Xywav™), an FDA-approved treatment for excessive daytime sleepiness or cataplexy in narcolepsy. Methods At study entry, participants were taking sodium oxybate (SXB) alone, SXB with other anticataplectics, other anticataplectics alone, or were anticataplectic treatment-naive. Participants taking SXB transitioned to the same LXB dose (gram-for-gram); oxybate-naive participants initiated LXB (4.5 g/night). TEAEs were analyzed in the safety population (N=201, received ≥1 study drug dose) during a 12-week open-label optimized treatment/titration period (while other anticataplectics were tapered/discontinued) and subsequent 2-week stable-dose period (SDP). TEAE duration was defined as time from TEAE start to end date (or end of SDP, if TEAE end date was unrecorded). Results LXB-emergent TEAEs varied by treatment at entry. Anticataplectic treatment-naive participants reported TEAEs including headache (n=36/90, 40%; median duration [range]=1 [1–76] day), nausea (n=19/90, 21%; duration=9 [1–37] days), and dizziness (n=15/90, 17%; duration=10 [1–117] days); peak incidence was week 2 (n=8/89, 9%) for headache, week 3 (n=3/88, 3%) for dizziness, and week 1 (n=6/90, 7%) for nausea. Anticataplectic treatment-naive participants (n=13/90, 14%) also reported decreased appetite, with relatively long duration (58 [2–358] days). Participants taking SXB alone reported TEAEs including headache (n=17/52, 33%; duration=1 [1–122] day) and diarrhea (n=4/52, 8%; duration=41 [2–101] days); peak headache incidence was week 4 (n=4/52, 8%); diarrhea had no peak. Participants taking other anticataplectics alone reported TEAEs including headache (n=14/36, 39%; duration=1 [1–94] day), nausea (n=9/36, 25%; duration=3 [1–16] days), and dizziness (n=9/36, 25%; duration=4 [1–29] days); peak incidence was week 1 (n=3/36, 8%) for headache, week 6 (n=2/32, 6%) for nausea, and week 4 (n=3/33, 9%) for dizziness. One participant taking SXB with other anticataplectics (n=1/23, 4%) reported headache in weeks 1–2 and 4; one reported nausea (4%) persisting from week 1 to 8. Overall, study discontinuations attributed to TEAEs were 20/57 (35%). Conclusion Most TEAEs with LXB treatment occurred early, were consistent with the known SXB safety profile, and were relatively short-lived (except decreased appetite). Participants previously taking SXB reported fewer TEAEs than oxybate-naive participants. Support (if any) Jazz Pharmaceuticals, Inc.