Effect of drugs on rat paw oedema induced by mercury.

1 Metallic mercury (0.04 ml) injected into the foot pad of rats induced a consistent inflammatory reaction, which at 4 h showed oedema but no cellular infiltration or vascular changes. The lesions exhibited lymphocytic infiltration, vasodilatation and haemorrhages at 24 and 48 h, and often became cystic after 2-3 weeks, before healing. The oedema volume at 4 h was used to test anti-inflammatory activity of drugs.2 Cortisone, phenylbutazone, indomethacin, acetylsalicylic acid, flufenamic acid and propranolol exhibited potent, dose-related anti-inflammatory activity. Aminopyrine, chloroquine and chlorpromazine were only moderately effective. Dimercaprol, adrenaline, and to some extent, mepyramine also inhibited mercury-induced oedema.3 This simple model of acute inflammation may be useful for preliminary tests of anti-inflammatory activity.