On 12 August, the US Food and Drug Administration (FDA) approved a new indication for Jazz Pharmaceuticals’ Xywav (calcium, magnesium, potassium and sodium oxybates) for the treatment of patients with idiopathic hypersomnia (IH), a rare neurologic disorder that can result in daytime sleepiness despite having a prolonged night of sleep.

Since Xywav’s first FDA approval last July for both cataplexy and excessive daytime sleepiness (EDS) associated with narcolepsy, its uptake in the US has soared, driven mainly by the favourable safety profile of its reformulation. This reformulation contains 92% less sodium in each dose compared to its predecessor and the gold standard of narcolepsy treatment, Xyrem (sodium oxybate). Because of this, Jazz is expected to undertake a switching strategy from its top-selling and market leader brand, Xyrem, to Xywav in order to offset Xyrem’s sales decline due to generics erosion as the brand approaches a loss of patent exclusivity in 2023. Given Xywav’s strong clinical and commercial profile, GlobalData expects its exponential growth trajectory to continue into 2027, reaching around $1.3bn in global sales.

In addition, the expanded use of Xywav in the IH space will further bolster the drug’s position ahead of the competition and help Jazz hold its lead in the narcolepsy market. Despite this, Xywav is still expected to face significant competition from recently launched products in the US, including Jazz’s own Sunosi (solriamfetol) and Harmony’s Wakix (pitolisant), both of which were approved by the FDA in 2019.

Some key opinion leaders (KOLs) previously interviewed by GlobalData indicated that Sunosi has demonstrated superior efficacy in treating EDS, a particularly challenging aspect of narcolepsy treatment. Sunosi is not, however, effective in treating cataplexy. KOLs also believed that although Wakix is not as effective as sodium oxybate drugs (Xyrem and Xywav), it represents a valid alternative for patients who cannot tolerate the side effects and would, therefore, be relegated to using a second-line treatment. As such, Xywav’s key competitive advantage is its enhanced safety and tolerability in patients with cardiovascular diseases due to its low-sodium formulation, in addition to its efficacy to treat symptoms of narcolepsy with cataplexy and being the only drug approved in IH to date.

Despite all this, a few barriers to Xywav’s uptake do exist. For example, the drug is a Schedule III controlled substance, which means that it has a potential risk of misuse or dependence. The drug will, therefore, only be available through a restricted programme known as the Risk Evaluation Mitigation Strategy (REMS) programme. The company plans to make the drug available for IH patients by the end of this year following the REMS implementation. On balance, GlobalData anticipates Xywav to be Jazz’s next blockbuster over the next few years in the narcolepsy and sleep disorder market.