ECR Pharmaceuticals, Richmond, VA, USA, sponsored the studies referred to in this article. Cephalon, Inc., Frazer, PA, USA, acquired the North American rights to cyclobenzaprine hydrochloride extended-release (AMRIX®) in August 2007. Support for this supplement was provided by Cephalon, Inc. Writing support was provided by Peloton Advantage, LLC, funded by Cephalon, Inc.