Jazz Pharmaceuticals and partner UCB have presented promising data from the first of two late-stage trials of sodium oxybate as a potential treatment for fibromyalgia.

The drug, which is currently marketed by the Belgian firm as Xyrem for the treatment of narcolepsy, was studied in a 548-patient Phase III trial and the findings reveal that sodium oxybate (known as JZP-6 in this new indication), achieved at least a 30% reduction in pain in both the 4.5g and 6g dosages, compared to placebo. Patients physical functioning and ability to perform daily tasks were significantly different from placebo for the 4.5g/night dose and approached significance for the 6g dose.

Patients on sodium oxybate also reported significant improvement in fatigue, another common symptom of fibromyalgia, at both doses. Adverse events were headache, nausea, dizziness, vomiting, diarrhoea, anxiety and sinusitis, and most of the cases were mild to moderate in nature.

The firms, which noted that only primary efficacy and safety data have been reviewed as yet and more than 90% of the subject have been enrolled in a second Phase III trial. Jazz anticipates submitting a New Drug Application for sodium oxybate to the US Food and Drug Administration by the end of 2009 and UCB will file it in Europe shortly after.

UCB noted that while the exact causes of fibromyalgia are unknown, it is believed to be a central nervous system condition, resulting from neurological changes in how the brain perceives and responds to pain. In addition to pain, the main symptoms are fatigue, disturbed sleep and morning stiffness.

If approval is achieved, JZP-6 will go up against Pfizer’s Lyrica (pregabalin), which was approved by the FDA in June 2007, and Eli Lilly’s Cymbalta (duloxetine), which got the green light in the USA in June this year.