Antinociceptive activity of methanolic extracts of St. John's Wort (Hypericum perforatum) preparation.

The analgesic effect of St. John's Wort plant preparation was evaluated using chemically induced pain models in adult albino mice. The intraperitoneal (i.p.) administration of 30-100 mg/kg of the preparation produced significant analgesic effect (75%) in acetic acid induced writhing and formalin licking tests. Based on its inhibitory effects on acetic acid induced writhes and both phases of the formalin test, the plant preparation seems to have central and peripheral analgesic properties. Its effect was found twice more potent than ibuprofen (100 mg/kg), a standard reference drug, in the acetic acid induced writhing test.