Analgesic effect of S (+)-flurbiprofen plaster in a rat model of knee arthritis: analysis of gait and synovial fluid prostaglandin E2 levels

Abstract Objectives We developed S (+)-flurbiprofen plaster (SFPP), a novel NSAID patch containing S (+)-flurbiprofen (SFP), a potent cyclooxygenase (COX) inhibitor. The purpose of this study was to assess efficacy of SFPP by analysing its effect on the gait disturbance and measuring the prostaglandin E2 (PGE2) production in synovial fluid in a rat model of knee arthritis. Methods Knee inflammation was induced in rats by intra-articular injection of a yeast suspension. Subsequently, an NSAID patch containing SFP, ketoprofen or loxoprofen was applied over the affected knee. Gait was assessed at 2, 4 and 6 h after application of the patch. The PGE2 concentration in the synovial fluid was measured after the gait assessment. Key findings Application of SFPP (0.125, 0.25, 0.5 or 1 mg/sheet) was followed by a decrease in the visual gait score at all the doses examined. In the case of the other two NSAID patches, only the ketoprofen patch (1 or 2 mg/sheet) and loxoprofen patch (5 mg/sheet) produced a decrease in the visual gait score. All of the NSAID patches decreased the PGE2 production in the synovial fluid. Conclusions These results suggest the potential usefulness of SFPP as an analgesic patch in patients with inflammatory joint pain.