US pharmaceutical company Vanda Pharmaceuticals (VNDA.US) said on Thursday that the US Food and Drug Administration (FDA) has refused to approve its drug for treating a digestive disorder, and has called for more research. The stock price fell by 10% at one point, and is currently down by over 8%.

Vanda is seeking FDA approval for the drug tradipitant to treat symptoms of gastroparesis. In response to the FDA's refusal, the company stated that the design of the additional studies requested by the FDA is inconsistent with the recommendations of the leading experts in the field, and added that they will continue to seek approval for the drug.

The company is also studying a drug to prevent motion sickness-induced vomiting, and plans to submit a separate application later this year.