On April 16, 2012 in In re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litigation and Eurand, Inc. v. Mylan Pharmaceuticals Inc., the US Court of Appeals for the Federal Circuit reversed the US District Court for the District of Delaware's obviousness determination concerning patents relating to extended-release muscle relaxant formulations. The Federal Circuit held that the district court committed multiple errors in its obviousness determination, including failing to consider the lack of a known pharmacokinetic/pharmacodynamic relationship for the claimed drug formulation in its obviousness analysis and determining that the patents-in-suit were obvious before considering the objective considerations of nonobviousness