1 The milky white
latex of the plant Calotropis procera induces inflammatory response upon accidental exposure and on local administration that could be effectively ameliorated by antihistaminic and standard anti-inflammatory drugs. 2 The aim of the present study was to evaluate the anti-oedematogenic and
analgesic effect of the
bradykinin antagonist,
bradyzide (BDZ) and the opioidergic
analgesic,
morphine (Mor) against inflammatory
hyperalgesia induced by the dried
latex (DL) of C.
procera in the rat paw oedema model. 3 An aqueous
solution of DL (0.1 ml of 1%
solution) was injected into the sub-plantar surface of the rat paw and the paw volume was measured at different time intervals. The inhibitory effect of
bradyzide and
morphine on oedema formation and hyperalgesic response was compared with that of
cyproheptadine (CPH), a potent inhibitor of DL-induced oedema formation. 4 The hyperalgesic response was evaluated by the dorsal flexion
pain test, compression test and by observing motility, stair-climbing ability, and the grooming behaviour of the rats. 5 The effect of these drugs was also evaluated against DL-induced writhings in the mouse model. 6 Both
bradyzide and
morphine inhibited DL-induced oedema formation by 30-40% and CPH was more effective in this regard (81% inhibition). The antihyperalgesic effect of both the drugs was more pronounced than that of CPH. Both
bradyzide and
morphine markedly inhibited the grooming behaviour and the effect of
morphine could be reversed by pretreatment with
naloxone. 7 Thus, our study shows that DL-induced oedema formation is effectively inhibited by antihistaminic/antiserotonergic
drug and associated
hyperalgesia by
analgesic drugs.