Xyrem is just the brand name for GHB. The company that currently owns the rights (Jazz Pharmaceuticals) pled guilty to felony misbranding in 2011, and in 2013 raised the price by 841%. More recently, in 2017, they sued multiple other companies attempting to produce generics, before settling on an exclusive licensing agreement with one of them. Ironically the headline on their website is "Improving Patients' Lives", but I imagine they aren't reducing the price because Xyrem makes up 74% of total sales [1]. The entire thing reeks of PE--tons of acquisitions.
[1] https://en.wikipedia.org/wiki/Jazz_Pharmaceuticals