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

The companies say that preliminary top-line results from the second trials of the drug, which is currently marketed by the Belgian firm as Xyrem for the treatment of narcolepsy, confirm the results of an earlier Phase III trial. The studies show that sodium oxybate significantly decreased pain and fatigue and improved daily function and patient global impression of change.

The latest Phase III trial lasted 14 weeks and included 573 adults with fibromyalgia and demonstrated significantly more patients treated with sodium oxybate achieved 30% or greater improvement in their pain compared to those on placebo. Patients' physical functioning and ability to perform daily tasks were highly statistically significantly different from placebo, Jazz and UCB noted, and people on sodium oxybate also reported significant improvement in fatigue, another common symptom of fibromyalgia.

The most common adverse events were nausea, dizziness, vomiting, insomnia, anxiety, somnolence, fatigue, muscle spasms, and peripheral oedema. However, the companies noted that sodium oxybate was generally well tolerated, with the majority of adverse events reported being mild to moderate in nature.

Iris Loew-Friedrich, UCB’s chief medical officer, said that the positive results of the two Phase III trials “are encouraging and suggest that subject to regulatory approval, this may offer a new treatment option”. The firms noted that only preliminary efficacy and safety data are available at the moment and Jazz expects to submit a New Drug Application for sodium oxybate to the US Food and Drug Administration by the end of the year.

UCB said it will consult with the European Medicines Agency “to define the path forward”. If approved, sodium oxybate will go up against Pfizer’s Lyrica (pregabalin) and Eli Lilly/Boehringer Ingelheim’s Cymbalta (duloxetine).