Analgesic activity of aqueous leaf extract of Phyllanthus amarus.

Various doses of the aqueous extract of Phyllanthus amarus (AEPA) were investigated for analgesic and anti-inflammatory activities using both thermal and chemical models of pain assessment in rats. The extract caused a significant (P < 0.05) dose related increase inhibition of the carrageenan-induced paw oedema in the rats. The inhibition produced by 200 mg/kg AEPA (70.20%) was significantly higher than that of the reference drug (Acetylsalicylic acid). The extract produced a marked analgesic activity by inhibiting both early and late phases of pain stimulus in Formalin-induced paw licking rats and also a significant and dose related increase in inhibiting the mean tail immersion duration (MITD) at varying water bath temperature (50 degrees C, 55 degrees C and 60 degrees C). This study thus established the anti-inflammatory and analgesic activities of Phyllanthus amarus.