EXTON, Pa. (AP) — ViroPharma Inc. said Wednesday that it lost $4 million in the fourth quarter as revenue fell as generic competition eroded sales of its antibiotic Vancocin and its costs increased.

ViroPharma said sales of Vancocin fell more than 90 percent after less-expensive generic versions went on sale. Costs grew as the company made a royalty payment to French drugmaker Sanofi that was connected to Vancocin sales and it spent more money marketing its drug Cinryze which is used to treat a rare genetic disorder.