Preliminary studies on local anesthetic and antipyretic activities of Spilanthes acmella Murr. in experimental animal models

OBJECTIVE: Spilanthes acmella Murr. (Family: Compositae) is a herb that grows throughout the tropics. It is used in the treatment of rheumatism, fever, sore throat, and hemorrhoids. A tincture of the flowers is used to relieve toothache. The leaves and flowers produce numbness of the tongue when eaten as salad. The present study was undertaken to evaluate the local anesthetic and antipyretic activities of S. acmella in experimental animal models. MATERIALS AND METHODS: Aqueous extract of S. acmella Murr. (SAM) was tested for local anesthetic action by (i) intracutaneous wheal in guinea pigs and (ii) plexus anesthesia in frogs. In both the models, 2% xylocaine was used as the standard drug. The anti-pyretic activity was determined by yeast-induced pyrexia in rats. Aspirin 300 mg/kg was used as the standard drug. RESULT: The test drug in concentrations of 10% and 20% produced 70.36% and 87.02% anesthesia respectively by the intracutaneous wheal compared to 97.22% anesthetic effect produced by 2% xylocaine (P<0.001). The mean onset of anesthesia with the test drug was 5.33±0.57 min compared to 2.75±0.31 min (P<0.001) for the standard drug in the plexus anesthesia model. In the anti-pyretic model, ASA in doses of 100, 200, and 400 mg produced dose-dependent reduction in mean temperature at various hours of observation. CONCLUSION: The present study shows that SAM has significant local anesthetic and antipyretic activities.