Salix Pharmaceuticals, Ltd. (NASDAQ:SLXP) today announced that the U.S. Food and Drug Administration (FDA) has extended the Prescription Drug User Fee Act (PDUFA) goal date for the Agency’s Priority Review of the New Drug Application (NDA) for Crofelemer 125 mg tablets for the proposed indication for the control and symptomatic relief of diarrhea in patients with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) on anti-retroviral therapy (ART). The FDA has notified Salix that it requires additional time for a full review of the submission and has extended the June 5, 2012 goal date by three months. The extended user fee goal date is September 5, 2012. The FDA did not request additional studies. About Crofelemer Crofelemer is a first-in-class, gastrointestinal agent of botanical origin. Crofelemer is a gut-targeted, orally administered, anti-secretory, anti-diarrheal agent that has minimal absorption. Crofelemer is a locally-acting product that is believed to possess dual novel mechanisms of action that might be effective in treating both acute infectious diarrhea and chronic diarrhea. Investigational studies support the use of crofelemer as an anti-secretory anti-diarrheal agent that may provide relief to patients through the inhibition of chloride secretion by both gut CFTR (Cystic Fibrosis Transmembrane Conductance Regulator Protein) as well as gut CaCC (calcium-activated chloride channel). Inhibiting CFTR and CaCC prevents the secretion of chloride and other ions, along with the water that passively follows chloride, out of the body into the intestinal lumen. This secretion leads to diarrhea, with the associated symptoms of dehydration, electrolyte imbalance, abdominal cramping, urgency and increased frequency. Additionally, crofelemer, unlike other anti-diarrheal agents, does not affect gut motility. In trials to date, crofelemer is well tolerated, and demonstrates a safety profile comparable to placebo. Crofelemer, if approved, would be a first-in-class CFTR inhibitor as well as a first-in-class CaCC inhibitor that would work as an anti-secretory anti-diarrheal drug.