AV608, a 4-aminopiperidine derivative, is a selective, specific, long-acting, orally active and potent nonpeptidic antagonist of the NK-1 receptor. AV-608 had been in phase II clinical trials for the treatment of social phobia and overactive bladder (OAB). This compound was originally discovered by Novartis, and then licensed to Areva Pharmaceuticals in October 2003. Addition this drug was in phase I clinical trial for the treatment of Irritable Bowel Syndrome (IBS), this disease is characterized by chronic abdominal pain and frequent comorbid anxiety. The substance P ⁄ neurokinin-1 receptor system is implicated in the regulation of both pain and anxiety, suggesting a potential therapeutic target in IBS. However, the researches on this drug candidate were discontinued in 2010.