ZymoGenetics Inc., developer and manufacturer of therapeutic proteins, was told by the Food and Drugs Administration that its promotion of the treatment Recothrom had false and misleading material according to a letter released today.

In a press release sent by ZymoGenetics on January 17, the company suggested that Recothrom was safer than a competitor treatment. The U.S. regulator ruled that the statement excluded importatn contextual information necessary to understand the limitation of that finding.

Recothrom is a protein that helps to control surgical bleeding. ZymoGenetics added the information requested by the FDA on its promotional materials of the product.

A a spokeswoman for the company confirmed that the incident would not affect sales of the product which sold $1 million in the first quarter of its release, according to the companys financial report.

Shares of ZymoGenetics were up 2.94 percent to $8.42 on the Nasdaq in after hours trading on Wednesday.