Effects of low-sodium oxybate on diary-based sleep time in a clinical study in adults with idiopathic hypersomnia

Prolonged nighttime sleep is a prominent symptom in many patients with idiopathic hypersomnia. The only US Food and Drug Administration-approved treatment for idiopathic hypersomnia is low-sodium oxybate (LXB; Xywav®), for which efficacy and safety were established in a double-blind, placebo-controlled, randomized-withdrawal study (NCT03533114). This post hoc analysis evaluated the effect of LXB treatment on sleep time.

Eligible participants (aged 18-75 years, primary diagnosis of idiopathic hypersomnia) began LXB treatment in an open-label titration and optimization period (10-14 weeks), entered a stable-dose period (SDP; 2 weeks), and were randomized to continue LXB or placebo in a double-blind, randomized-withdrawal period (DBRWP; 2 weeks). Sleep parameters, including 24-hour self-reported total sleep time (TST), nocturnal TST, and total nap duration, were analyzed using daily electronic sleep diary data collected ≥2 weeks during 3 different study periods.

In total, 3917 daily records from 148 participants were analyzed. During open-label LXB treatment, from baseline to the end of SDP, there were decreases in median 24-hour TST (from 513.3 minutes to 468.8 minutes), nocturnal TST (from 495.0 minutes to 454.3 minutes), and total nap duration (from 16.3 minutes to 7.8 minutes). During DBRWP, estimated median differences between LXB and placebo in 24-hour TST, nocturnal TST, and total nap duration were -25, -9, and -12 minutes, respectively. Common treatment-emergent adverse events (≥10 % of participants) were nausea, headache, dizziness, anxiety, and vomiting.

Open-label LXB treatment in adults with idiopathic hypersomnia was associated with reductions in 24-hour TST, nocturnal TST, and total nap duration.