Xywav (calcium, magnesium, potassium, and sodium oxybates), a CNS depressant distributed by Jazz Pharmaceuticals, was approved in August 2021 for treatment of Idiopathic Hypersomnia (IH), a condition characterized by recurrent excessive daytime sleepiness (EDS), typically with ‘sleep drunkenness and/or naps that are unrefreshing and long (greater than 1 hour).’1 According to Jazz, there are approximately 37,000 patients in the U.S. with IH, which they claim is an underestimation due to a lack of patient and physician awareness.2
Self-report tools include the Idiopathic Hypersomnia Severity Scale (IHSS) and the Epworth Sleepiness Scale (ESS). IHSS scores range from 0–50, with a score of 26 indicating untreated IH.’3 The ESS measures the likelihood of dozing off in various scenarios, including ‘sitting and reading, watching television, and laying down to rest in the afternoon when circumstances permit.’4 The scale ranges from 0–24: ‘would never doze’ (0 points) to ‘high chance of dozing’ (3 points), with scores ≥10 suggesting EDS.4
Both quizzes are found on www.sleepcountshcp.com (targeted to healthcare providers) and on www.livingwithih.com (targeted to patients), websites funded by Jazz.5,6 These questionnaires may cause people to mistakenly believe they have IH when their tiredness may be due to work, academic, and/or family responsibilities, or poor sleep hygiene. Online questionnaires and disease awareness campaigns, often in partnership with IH organizations, such as ‘Sleep Counts,’ ‘Living with IH,’ and the Hypersomnia Foundation, may lead to overdiagnosis of IH, and increased use of Xywav.
IH is included in the International Classification of Sleep Disorders (ICSD) manual. It does not appear in DSM-IV, though conditions with similar diagnostic criteria include Hypersomnolence, Idiopathic CNS Hypersomnolence, Primary Hypersomnia, and Unspecified Hypersomnolence Disorder.
Because IH is a chronic condition, Xywav may be used long-term, which is potentially concerning since users may develop dependence, tolerance and possibly withdrawal symptoms on discontinuation.7 In fact, sodium oxybate is identical to sodium gamma-hydroxybutyrate (GHB), a sedating recreational drug with a reputation as a date rape drug.8
Xywav is the successor to Xyrem (sodium oxybate). The only difference is that Xywav adds calcium, magnesium, and potassium, and contains 92% less sodium than Xyrem. Prior to the IH indication, Xywav was FDA-approved in 2020 to treat EDS and cataplexy associated with narcolepsy.9 Sleep Counts emphasizes that ‘IH is a unique medical disorder that is different from other disorders (such as narcolepsy, sleep apnea, or depression).’10 Is IH truly a different disorder, or it simply a form of narcolepsy?
Sleepiness during the day should not automatically warrant a sleep disorder diagnosis. IH may be an example of condition branding, a marketing tactic in which a specific disease is linked to a specific drug. ‘Educational’ websites and questionnaires like these could scare patients who are merely tired into thinking that they have IH, leading to overdiagnosis of the disease and increased use of an addictive drug.
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