8:31AM Xenoport Submits Investigational new drug application for XP23829 as a potential treatment of RRMS (XNPT) 5.87 : Co announced that it has submitted an Investigational New Drug application to the FDA to begin clinical studies of XP23829 as a potential treatment for relapsing-remitting multiple sclerosis (RRMS). Following clearance of the IND by the FDA, the first Phase 1 clinical trial to be conducted in healthy subjects will commence.