[Action of piroxicam on allergic inflammation]

Effects of piroxicam on allergic inflammation were investigated with allergic air pouch inflammation and antigen-induced arthritis in rats. In allergic air pouch inflammation, piroxicam exerted a dose-dependent inhibition (1-10 mg/kg, p.o.) of the exudate production, the migration of leukocytes and the release of lysosomal enzyme into the exudate; and its potency was superior to that of indomethacin and equivalent to that observed with prednisolone. In contrast with this, the suppressive effect of piroxicam on non-allergic air pouch inflammation was as weak as indomethacin. Prednisolone showed a similar effect on both types of air pouch inflammation. In antigen-induced arthritis, piroxicam showed a dose-dependent (0.3-3 mg/kg, p.o.) inhibitory effect on knee joint swelling and an improving action on the functional disorder of the inflamed joint. On this model, piroxicam was 3 to 4 times more active than both indomethacin and prednisolone. In non-allergic joint inflammation induced with croton oil in rats, however, the anti-inflammatory potency of piroxicam was almost equal to those of indomethacin and prednisolone. Piroxicam showed more potent inhibition than indomethacin on heterologous passive cutaneous anaphylaxis in rats, but showed only a slight inhibition on the increased vascular permeability caused by histamine and bradykinin. Piroxicam had no influence upon the plaque-forming cell response and the delayed hypersensitivity reaction in mice; furthermore, the hemolytic activity of complement in guinea-pig serum was scarcely affected by piroxicam in vitro. These results indicate that piroxicam possesses prominent efficiency on allergic inflammation and may function on several activities of inflammatory cells.