The Food and Drug Administration (FDA) has approved Xywav (calcium, magnesium, potassium, and sodium oxybates) for the treatment of idiopathic hypersomnia.
Idiopathic hypersomnia is a rare neurological sleep disorder characterized by chronic excessive daytime sleepiness. In addition to excessive daytime sleepiness, symptoms may include severe sleep inertia or sleep drunkenness (a core symptom of idiopathic hypersomnia), as well as prolonged, non-restorative nighttime sleep, cognitive impairment, and long and unrefreshing naps.
The approval of Xywav was largely based on the results of a phase 2/3 double-blinded, placebo-controlled, randomized withdrawal study. The results demonstrated Xywav’s efficacy and safety as a treatment for idiopathic hypersomnia in adults. Notably, patients who received Xywav demonstrated statistically significant and clinically meaningful differences in change in Epworth Sleepiness Scale score (primary endpoint), as well as in the Patient Global Impression of Change and the Idiopathic Hypersomnia Severity Scale (secondary endpoints), compared to those who received placebo. The most common adverse events as a result of the treatment observed in the study were nausea (21.4%), headache (16.2%), dizziness (11.7%), anxiety (10.4%) and vomiting (10.4%).
Xywav has a boxed warning for central nervous system depression and abuse and misuse. The active moiety of Xywav is oxybate, also known as gamma-hydroxybutyrate (GHB), a Schedule I controlled substance. Abuse or misuse of illicit GHB has been associated with serious side effects including seizures, trouble breathing, changes in alertness, coma, and death. Clinically significant respiratory depression and reduced level of alertness has occurred in adult patients taking sodium oxybate.
Because of the potential risks associated with Xywav, it is subject to strict safety controls on prescribing and dispensing under a program called a Risk Evaluation and Mitigation Strategy (REMS). Only a certified pharmacy that ships directly to patients can dispense Xywav. Xywav will not be available in retail pharmacies.
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