Disclosed is a mucoadhesive delivery device suitable for transrnucosal administration of an effective amount of a fentanyl compound to a subject, the mucoadhesive device comprising a fentanyl compound disposed in a mucoadhesive polymeric diffusion environment which has a pH between 6.5 and 8； and a barrier layer disposed relative to the mucoadhesive polymeric diffusion environment such that a unidirectional gradient is created upon application of the device to a mucosal surface.
