Pseudo-akuammigine, an alkaloid from Picralima nitida seed extract was investigated for anti-inflammatory and analgesic actions using the carrageenan-induced rat paw oedema and the rat tail flick. The alkaloid, at 1.0, 5.0 and 50 mgkg(-1)(,) dose-dependently inhibited the mean maximal paw swelling attained during 6 h to 78.2+/-2.1, 74.7+/-4.3 and 59.5+/-2.3% of the mean control value respectively when administered p.o. 1 h before induction of oedema. At the same dose levels, the total paw swelling over the 6-h period was also significantly (P<0.05) reduced to 83.2+/-9.7, 73.0+/-5.0 and 55.8+/-8.3% of the mean control response respectively. When administered after induction of oedema, psi-akuammigine (5.0 mgkg(-1)) significantly (P<0.05) reduced established rat paw swelling to 82.8+/-4.6% of the control response after 5 h. As an analgesic, psi-akuammigine was 3.5 and 1.6 times less potent than morphine and indomethacin respectively. The ED(50) values were Morphine (2.9 microM), psi-akuammigine (10 microM) and indomethacin (6.3 microM). Naloxone (1.0 mgkg(-1)) significantly (P<0.05) antagonised the analgesic action of the alkaloid by 35.8+/-6.8%. Pseudo-akuammigine therefore exhibits anti-inflammatory and analgesic actions. The analgesic actions are mediated via interaction with opioid receptors.