Local anesthetic action of spilanthes acmella.

The local anesthetic action of ethanol extract of Spilanthes acmella was studied in guinea pigs and frogs’ sciatic nerves. Subcutaneous injection of 0.1 ml of 10% test solution into guinea pig’s back revealed that the onset of action occurred immediately after injection and lasted for 21 minutes. The duration of action was significantly shorter than that of 2% lidocaine (p<0.001,). The action potential of isolated frog’s sciatic nerve was completely abolished within 5 minutes after application of the test solution. The tissue apecimen obtained from guinea pig’s back muscle showed mild congestion of small blood vessels and mild intercellular edema. There was no significant difference as comparing to lidocaine injection. The results indicated that Spilanthes acmella possessed local anesthetic activity and further clinical trial should be investigated.