ABSTRACT
Byrsocarpus coccineus (Schum. and Thonn.) is used as an herbal remedy for earache; muscular and rheumatic pains in West Africa. To validate the claim of the users; the analgesic effect of the aqueous leaf extract of the plant was studied in mice and rats using acetic acid-induced writhing; formalin; tail immersion; and cold-water tail flick pain tests. The extract (50 - 400mg/kg; p.o) showed a dose dependent and significant (p0.05) inhibition of pain in the acetic acid-induced writhing; tail immersion; tail flick and the formalin (second phase) tests. The extract (400mg/kg) gave a significantly (p0.05) higher inhibition than acetylsalicylic acid; ASA; (100mg/kg; p.o) in the acetic acid-induced writhing test. Its effect on the second phase of the formalin test was comparable to that of ASA. The elevation of pain threshold at 60 minutes post-treatment produced by 400mg/kg of the extract in the tail immersion and tail flick tests were slightly lower than that of morphine (2mg/kg; s.c). The results suggest that the aqueous leaf extract of Byrsocarpus coccineus possesses effective analgesic activity mediated via peripheral and central mechanisms