Last season, both players received four-game suspensions for using a product containing a possible masking agent for steroids.
The players are arguing the positive test results should be excused because the NFL knew about the presence of bumetanide, an unlisted ingredient in StarCaps, an over-the-counter supplement, and did not advise the league's players.
Neither has tested positive for steroids, and Friday's ruling by a three-judge panel of the 8th U.S. Circuit Court of Appeals in St. Louis upheld previous rulings by U.S. District Judge Paul Magnuson in Minneapolis this this summer.
The players' case against the NFL continues in Hennepin County (Minn.) District Court.