STUDY OF HEALTHY VOLUNTEERS: This double blind study (bioadhesive plaster of diclofenac epolamine versus placebo), showed that the application of diclofenac epolamine for 24 hours induced a selective hypoanalgesic effect on the muscle, proportional to the degree of hypersensitivity to the pain observed in baseline conditions. The enhanced effect on the hyperalgic muscle can be explained by the direct impact of the active ingredient on the nociceptors and/or its inhibiting effect on the local production of prostaglandins. STUDY OF PATIENTS SUFFERING FROM BILATERAL OSTEO-ARTHRITIS OF THE KNEE: In a 24 hour trial of the treatment (bioadhesive plaster impregnated with diclofenac epolamine (Flector Plaster) versus placebo), the active treatment had a significant impact on the spontaneous pain during rest that was enhanced during mouvement. In a longer term trial (72 hours), the regression of the spontaneous pain on the visual analog scale appeared even more significant, still lasting 96 hours after withdrawal of the plaster, not only at rest but also on mouvement.