Jazz Pharmaceuticals PLC said a late-stage study of JZP-258 met its main goal of reducing attacks of physical collapse among patients with narcolepsy, a sleep disorder.

Narcolepsy is a chronic neurological disorder characterized by excessive daytime sleepiness. Cataplexy, which occurs in about 70% narcolepsy patients, refers to a sudden loss of muscle tone with retained consciousness. It is usually triggered by strong emotions, such as laughter, surprise or anger and can lead to sporadic partial attacks to frequent complete collapse.

The phase 3 study involved 201 patients and compared JZP-258 with placebo in treating cataplexy in adult patients with narcolepsy. The patients included those previously treated with Xyrem, or having no treatment with Xyrem, as well as those with or without other anti-cataplectic treatments.

Xyrem, or sodium oxybate, is a top-selling drug of Dublin-based Jazz Pharmaceuticals, which is also used to treat narcolepsy and cataplexy. However, JZP-258 has 92% less sodium than Xyrem.

The study demonstrated that JZP-258 showed a statistically significant difference in reducing the weekly number of cataplexy attacks while placebo led to a worsening of attacks.

JZP-258 also met its secondary goal of showing a statistically significant difference in the measure of daytime sleepiness compared to placebo. The drug's safety profile was found to be similar to Xyrem. However, two patients reported serious side effects linked by the investigator to JZP-258.

Narcolepsy patients need a new, low-sodium oxybate formulation as excessive consumption of sodium is linked with an increased risk of stroke, cardiovascular disease and other adverse outcomes, said Michael Thorpy, a director at Montefiore Health System in New York.

The company plans to discuss results with the U.S. Food and Drug Administration in order to proceed with a new drug application for JZP-258.