Disclosed is a mucoadhesive delivery device suitable for transrnucosal administration of an effective amount of a buprenorphine compound to a subject, the mucoadhesive device comprising: a buprenorphine compound of the formula disclosed herein or pharmaceutically acceptable salts or esters thereof disposed in a mucoadhesive polymeric diffusion environment which has a pH between 4 and 7.5； wherein, R3 is selected from -C1-4 alkyl group or a cycloalkyl-substituted-C1-4 alkyl group； R4 is selected from - C1-4 alkyl； R5 is -OH or taken together, R4 and R5 form a =O group； and R6 is selected from -H or a - C1-4 alkyl group 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.
