Analgesic Activity of Water Extract of Spilanthes acmella Flowers on Rats

Abstract

The objective of this study was to evaluate the analgesic potential of fresh flowers of Spilanthes acmella Murr. (family: Compositae) used by some Sri Lankan traditional medical practitioners to suppress toothache. Different doses of water extract of fresh flowers (111,335 and 671 mg kg-1 ) were orally administered to male rats and their analgesic potential was determined at different post treatment periods by using hot plate and tail flick tests. Sedative potential of the extract was evaluated by using rat hole board technique. The extract was well tolerated. A dose-dependent analgesic activity with a EC50 =313 mg kg-1was evident when evaluated in hot plate but not in tail flick test. This analgesic activity had a rapid onset and short duration of action and was not blocked by naloxone, an opioid receptor antagonist. The mid dose of the also induced significant sedation, It is concluded that the analgesic activity is mediated supra-spinally accompanied with sedation.