Active substance concentration in articular and periarticular tissues of the knee joint after cutaneous application of diclofenac-diethylammonium emulgel

The purpose of the present study was to investigate whether cutaneous application of diclofenac-diethylammonium around the knee joint will be able to provide effective concentrations in the articular and surrounding tissues; furthermore, to determine the mechanism of migration of therapeutical substances in the tissues. Two groups of patients were formed who were treated by cutaneous application of diclofenac-diethylammonium two to five days prior to total knee replacement. One group received three times a day 80 mg applied to the ipsilateral and the other group to the contralateral knee. During surgery specimens of different tissues were taken and the diclofenac concentration was evaluated by high-performance liquid-chromatography. Significant differences in concentration were found, determined by the Wilcoxon test between the two groups concerning skin, subcutis and muscle, whereas the diclofenac concentration of the intraarticular tissues did not show significant differences. We can conclude from these data that direct penetration into the surrounding tissues of the knee can be achieved, however, direct penetration into the articular structures could not be confirmed.