The Study of Analgesic Effects and Acute Toxicity of Tripleurospermum disciforme in Rats by Formalin Test.

ABSTRACT Previous studies have demonstrated the anti-inflammatory effect of Tripleurospermum disciforme extract in rats with a hind paw edema test. The present study was done to further characterize this anti-inflammatory effect using a formalin test in the intact rats, specifically studying the analgesic effect as well as its toxicity effect by determination of LD50 using graded oral doses of T. disciforme. The effects of graded doses of T. disciforme were investigated following intraperitoneal (IP) administration. Forty-eight rats were used in six groups of studies. The first group (control) received formalin 2.5%, the second group formalin 2.5% + saline, and the third group formalin 2.5% and morphine; three other groups received formalin 2.5% and 15 mg/kg, 30 mg/kg, and 60 mg/kg. After 5, 15, 30, 45, 60 min the pain responses were measured T. disciforme 60 mg/kg had a significant analgesic effect and this effect was equal to morphine 2 mg/kg in the chronic phase of the formalin test. To assess the utility of T. disciforme, the toxic effect of extract was studied by determination of LD50 using graded oral doses of 50, 500, and 5000 mg/kg of T. disciforme to fasted rats and LD50 was measured after 24, 48, and 72 hours. In conclusion, these studies show that T. disciforme is significantly nontoxic at doses required as analgesic drug and higher doses of T. disciforme could produce significant analgesic effects and confirm its previous significant anti-inflammatory effect.