Treatment Effect of Low-Sodium Oxybate in Idiopathic Hypersomnia Based on ESS, IHSS Scores: Richard Bogan, MD, FCCP, FAASM

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"When they reached a stable dose, we randomized them to a placebo group for 2 weeks. Those patients got sleepy and IHSS score got worse again, indicating that they had worsening of their sleepiness."

After years of only off-label, wake-promoting therapies available for use, in August 2021, the FDA approved low-sodium oxybate, also known asJZP-258 (Xywav; Jazz Pharmaceuticals), a combination agent of calcium, magnesium, potassium, and sodium oxybates, for the treatment of idiopathic hypersomnia, becoming the first treatment approved for this indication. The supplemental new drug application which fueled the approval, included data from a positive phase 3 study (NCT03533114) which showed that the agent was safe and effective for adults with the condition.

At the 2022 SLEEP Annual Meeting, June 4-8, in Charlotte, North Carolina, two post-hoc analyses of that trial looked at treatment response for low-sodium oxybate based on the 14-item, Idiopathic Hypersomnia Severity Scale (IHSS) and the 8-item, self-reported Epworth Sleepiness Scale (ESS). In the first analysis, more than 80% of the participants achieved a clinically meaningful response based upon IHSS total score less than 22, and up to 98% demonstrated a decrease in total IHSS score of at least 4 points by the end of the stable-dose period.1 Similarly, in the second analysis, over 80% of participants achieved a clinically meaningful response of less than 10 on ESS, and up to 95% demonstrated a decrease of at least 4 points in total ESS score.²

To learn more about the findings, NeurologyLive® sat down with Richard Bogan, MD, FCCP, FAASM, associate clinical professor, University of South Carolina School of Medicine, and associate clinical professor, Medical University of South Carolina. Bogan provided context on the clinical significance of the data and why changes on these 2 measures are important to patients with idiopathic hypersomnia.

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REFERENCES
1. Dauvillers Y, Chen A, Steininger T, Macfadden W, Rosenberg R. Efficacy of lower-sodium oxybate in the treatment of idiopathic hypersomnia: evaluation of response based on the idiopathic hypersomnia severity scale score. Presented at: SLEEP Annual Meeting, 2022; June 4-8; Charlotte, NC. Abstract 0390.
2. Rosenberg R, Chen A, Steininger T, Macfadden W, Dauvillers Y. Efficacy of lower-sodium oxybate in the treatment of idiopathic hypersomnia: evaluation of the response based on the Epworth Sleepiness Scale score. Presented at: SLEEP Annual Meeting, 2022; June 4-8; Charlotte, NC. Abstract 0389