New Mixed-Salt Oxybates Effective for Treatment of Hypersomnia in Adults 

 A phase 3 study (NCT03533114) has evaluated use of mixed calcium-, magnesium-, potassium-, and sodium-oxybates (Xywav; Jazz Pharmaceuticals, Philadelphia, PA) for treatment of idiopathic hypersomnia in adults. After all participants in the trial were treated with the mixed oxybates, they were randomly assigned to continue receiving oxybates or be switched to placebo. Those who remained on oxybates maintained their scores on the Epworth Sleepiness Scale (ESS), whereas those treated with placebo had increases in sleepiness (P<.0001). Similar efficacy of treatment vs placebo was shown on the Patient Global Impression of Change (PGIc) and Idiopathic Hypersomnia Severity Scale (IHSS)  (P<.0001 for both measures). 

A supplemental new drug application (sNDA) to the FDA for this indication is anticipated as early as the first quarter of 2021. The FDA granted Fast Track designation to the oral solution in September 2020.

The phase 3 study of the mixed-salt oxybates was a multinational double-blind placebo-controlled randomized withdrawal study in which 115 adults had titration and optimization of mixed-salt oxybate over 14 weeks, followed by a stable-dose of mixed-salt oxybate for 2 weeks. Participants were then randomly assigned to continue the mixed-salt oxybate or have a placebo substituted for 2 weeks. 

Mixed-salt oxybate was approved in July 2020 by the Food and Drug administration (FDA) for the treatment of cataplexy or excessive daytime sleepiness in participants ages 7 years and more with narcolepsy. The oral solution is not currently approved by regulatory authorities for the treatment of idiopathic hypersomnia.