Calcium, Magnesium, Potassium and Sodium Oxybates (Xywav(®)) in Sleep Disorders: A Profile of Its Use

Calcium, magnesium, potassium and sodium oxybates (Xywav(®); hereafter referred to as lower-sodium oxybate), a new oxybate formulation with a greatly reduced sodium burden compared with previously approved sodium oxybate (Xyrem(®)), is approved for the treatment of cataplexy and excessive daytime sleepiness (EDS) in adults and children aged ≥ 7 years with narcolepsy, and is the first drug approved for the treatment of idiopathic hypersomnia in adults in the USA. In two pivotal, double-blind, placebo-controlled, phase 3 trials of randomized-withdrawal design, lower-sodium oxybate effectively improved cataplexy and EDS in adults with narcolepsy, and EDS and overall idiopathic hypersomnia symptoms in adults with idiopathic hypersomnia during open-label titration and optimization periods. At the end of the double-blind, randomized withdrawal period, participants randomized to switch to placebo experienced significant worsening in these symptoms compared with those randomized to continue lower-sodium oxybate. Furthermore, worsening in patient- and clinical-rated global scales, as well as measures of health-related quality of life were also seen with placebo versus lower-sodium oxybate. Lower-sodium oxybate is generally well tolerated, with the tolerability profile being largely consistent to that seen with sodium oxybate. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40263-022-00912-6.