Salix Pharmaceuticals, Ltd announced that the US FDA has extended the Prescription Drug User Fee Act (PDUFA) goal date for the Agency's Priority Review of the efficacy supplement to NDA 21–361 for Xifaxan (rifaximin) 550 mg Tablets for the proposed indication of the treatment of non–constipation irritable bowel syndrome (Non–C IBS) and IBS–related bloating. The FDA has notified Salix that it requires additional time for review of the application and has extended the December 7, 2010 goal date by three months. The extended user fee goal date is March 7, 2011.

"The extension of the PDUFA goal date is not unexpected, given the Agency's historical management of Priority Reviews," stated Bill Forbes, Pharm.D., executive vice president and chief development officer, Salix Pharmaceuticals. "We are encouraged by the productive interactions we continue to have with the Agency during the review and believe it is unlikely that there will be an advisory committee meeting for this submission. We look forward to the completion of the review by the new goal date."

Rifaximin is a gut–selective antibiotic with negligible systemic absorption and broad–spectrum activity in vitro against both gram–positive and gram–negative pathogens.