Comparative study between steroidal and nonsteroidal anti-inflammatory drugs on the mode of their actions on vascular permeability in rat carrageenin-air-pouch inflammation.

In an attempt to clarify mechanisms of anti-inflammatory actions of steroidal and nonsteroidal anti-inflammatory drugs with special reference to the possible role of E type prostaglandins in the inflammatory process, mode of actions of these drugs was investigated by using acute exudative stage and chronic proliferative stage of carrageenin-air-pouch inflammation in rats. This inflammation was induced on the back of rats by subcutaneous injection with air and carrageenin solution. Plasma exudation in the inflammation locus was determined with the aid of radioiodinated serum albumin. In the acute exudative stage of this inflammation, a single oral administration of dexamethasone, indomethacin, phenylbutazone or aspirin all exerted potent anti-exudative effect, while in the chronic proliferative stage, only dexamethasone was effective in inhibiting the exudation of the labeled albumin. Prostaglandin E level in the exudate of the acute stage inflammation was suppressed by either dexamethasone or indomethacin in accordance with the inhibition of the vascular permeability. These results suggest (1) significant role of prostaglandin E in the acute exudative inflammation, (2) similarity between steroidal and nonsteroidal anti-inflammatory drugs in the mechanism of their anti-exudative actions in the acute inflammation, (3) independency of the exudative process in the chronic proliferative inflammation from prostaglandins and (4) role of extra-prostaglandin mechanism(s) for the anti-exudative action of the anti-inflammatory steroids.