Vanda Pharmaceuticals Inc. (NASDAQ: VNDA) announced that the FDA issued a complete response letter to its new drug application (NDA) seeking approval for its pipeline candidate, tradipitant for the treatment of symptoms in gastroparesis. Shares of the company were down 6.1% on Sept. 19 following the announcement of the news. Marked by delayed gastric emptying, gastroparesis is a serious condition that slows down the stomach’s ability to empty its contents. The FDA has not approved any effective medicine for treating gastroparesis in more than 40 years. Year to date, shares of Vanda have increa…