Anti-nociceptive effect of Tanacetum Fisherae on formalin-induced inflammatory pain in rats

Introduction: The management of pain and inflammation related problem is a real challenge that people face daily. Although several drugs are available for these conditions, medicinal plants are believed to be an important source of new chemical substances with potential therapeutic effects. The objective of current study was to investigate the anti-nociceptive effect of Tanacetum Fisherae which has been traditionally used for treatment of pain. Methods: In this experimental study, formalin test was performed with drug (Tanacetum Fisherae) or DMSO pretreatment 30 min prior to formalin injection in 40 male Wistar rats. Fifty microliters of 2.5% formalin was injected into the plantar surface of the right hind paw. Immediately after injection, licking and flinching number and paw-shaking responses were observed at 5-min intervals for 1 h. Animals were divided into five experimental groups. There were 8 animals in each group. Each group received vehicle (7% DMSO) or Tanacetum Fisherae essential oil (25, 50 or 100 &mu;g) or morphine (5 mg/kg). Two-way and one-way ANOVA were used for data analysis. Differences were considered significant at the level of P<0.05 (with 95% confidence interval). Results: Results showed that Tanacetum Fisherae essential oil dose dependently reduced licking and flinching number and also pain score in the late (15-35 min) and recovery phase (35-60 min) of formalin test (p<0.05, p<0.01, and p<0.001). It had no anti-nociceptive effect (p>0.05) in early (0-5 min) phase and interphase (5-15 min). Conclusion: Results demonstrate the effectiveness of Tanacetum Fisherae to mitigate the inflammatory pain.