Jazz Pharmaceuticals, Inc. announced completion of enrolment in the first of two phase III pivotal clinical trials of JZP-6 (sodium oxybate) for the treatment of fibromyalgia.

"Completion of enrolment in this trial is a key milestone in the JZP-6 program. We expect to report top line results from this trial in the fourth quarter of 2008," said Samuel Saks, MD, CEO.

The JZP-6 phase III clinical trial program includes two randomized, double blind, placebo-controlled studies. The first study has completed enrolment of 550 fibromyalgia patients at 65 centre in the US. The second phase III study is enrolling patients at sites in the US and Europe. The primary endpoint for both studies is the change from baseline in pain based on the pain visual analog scale, which the US Food and Drug Administration (FDA) and the European Medicines Agency have indicated is the appropriate primary endpoint.

In a phase II clinical trial completed in 2005, fibromyalgia patients taking sodium oxybate, the active ingredient in JZP-6, achieved a statistically significant improvement in pain compared to placebo based on the pain visual analog scale. These results need to be confirmed in the ongoing phase III clinical trials.

The JZP-6 clinical programme also includes an open-label continuation trial to provide long-term safety data. Enrolment in this trial is underway, and the trial is open to patients who complete one of the two pivotal phase III trials.

Sodium oxybate is approved by the FDA for the treatment of excessive daytime sleepiness and cataplexy (the sudden loss of muscle tone) in patients with narcolepsy. Sodium oxybate has not been approved for the treatment of fibromyalgia.

Fibromyalgia is a chronic pain syndrome defined by widespread pain lasting at least three months. According to the American College of Rheumatology, between two and four percent of the US population suffers from fibromyalgia. Fibromyalgia is believed to be a central nervous system condition. In addition to pain, fibromyalgia patients often suffer from a combination of muscle stiffness, fatigue, disturbed sleep, restless legs syndrome and impaired memory and concentration.