Electron microscopic observations comparing the gastric mucosal damage induced in rats and pigs by benoxaprofen and aspirin,reflecting their differing actions as prostaglandin-synthesis-inhibitors.

The ultrastructural changes in the gastric mucosa induced by oral administration of aspirin (2 x 125 mg/kg/day) were compared with the effects of benoxaprofen (20 mg/kg/day) in pigs and normal and arthritic rats after 10 or 14 days'' treatment respectively. The object was to compare the effects of drugs having different effects on prostaglandin-synthesizing systems on the development of gastric mucosal damage. Benoxaprofen caused less gastric damage than aspirin. There were fewer lesions in benoxaprofen-treated animals and those which were seen were much less extensive. There were qualitative similarities between the effects of the drug treatments. There were also differences in the mucosal changes produced by both drugs in pigs and rats. This included (1) extravasation of erythrocytes which was seen in rats but not pigs, and (2) interstitial changes also seen in rats but not pigs. These interspecies variations may be due to differences in the resistance of the capillaries to drug effects. There were no differences in the mucosal-cell damage seen in normal compared with arthritic rats.