Analgesic and antiarthritic effects of piperine in rat models of paw edema and arthritic ankle. (a) Piperine showed analgesic effects in carrageenan-induced paw edema. The y axis indicated the pressure (g) that was tolerated before the rat exhibited signs of pain. Arthritic symptoms were measured by (b) relative paw volume, expressed as a function of the unaffected paw (100%). (c) The ankle flexion pain score (a value of 0 represents no indication of pain); and (d) the weight distribution ratio (a value of 50% indicated that weight was equally distributed between the two hind paws). The results indicated that piperine had antiarthritic effects. Con = control mice, Cele = celecoxib (100 mg/kg), PI-20/PI-100 = pierine at 20/100 mg/kg, Pre = prednisolne. Values are expressed ± standard error of the mean (SEM). *P < 0.05, **P < 0.01, ***P < 0.001 vs control group.