Both the companies are evaluating the complete response letter, in which the FDA has indicated that a preclinical finding of pancreatic acinar cell tumors in rats was of sufficient concern to preclude approval of Horizant for RLS at this time.
FDA acknowledged that similar findings were known for Gabapentin at the time of its approval for refractory epilepsy, but concluded that the seriousness and severity of refractory epilepsy justified the potential risks. The companies are assessing the appropriate next steps and will be communicating with FDA.
Reportedly, NDA for Horizant was submitted to the FDA by the companies on January 9, 2009.