Inflammatory edema induced by 1,8-cineole in the hindpaw of rats: a model for screening antiallergic and anti-inflammatory compounds.

A number of clinically useful drugs were tested for their ability to inhibit the inflammatory edema induced by 1,8-cineole (cineole), a terpenoid oxide, in the hindpaw of rats. Paw edema was measured by plethysmography following subplantar injection of cineole (20 μl/paw). The edema inducing effect of cineol was rapid in its onset (early phase, 0.5-1 h); attained slowly its peak level at 2 h and thereafter remained relatively constant up to 5 h post-injection (late phase, 2-5 h). Rats pretreatad with the antiallergic drugs cyproheptadine, ketotifen and cromoglycate demonstrated significant inhibition at both the early and the late phases of paw edema, while the rats that received nonsteroidal anti-inflammatory compounds phenylbutazone, indomethacin, and piroxicam and steroidal anti-inflammatory drug dexamethasone exhibited significant edema inhibition only at the late phase, suggesting that the anti-allergic drugs are more effective in this model of acute inflammation. However, all the drugs tested were found to inhibit the late phase edema effect of 1,8-cineole. The data indicate that 1,8-cineole-induced acute inflammation is a useful model to screen compounds that possess anti-allergic and anti-inflammatory potential.