The influence of a new corticosteroid, budesonide, on anaphylactic bronchoconstriction and SRS-A release in the guinea pig.

Groups of guinea pigs sensitized with ovalbumin were treated with budesonide and beclomethasone dipropionate, respectively, in an intraperitoneal dose of 50 mg/kg. 20 h later, the anaphylactic release of histamine and slow reacting substance of anaphylaxis (SRS-A) from chopped lung tissue was studied. Whereas the corticosteroids studied had no effect on the tissue content of histamine or on the amount of antigen-induced release of this autacoid, budesonide and beclomethasone dipropionate to a great extent inhibited the release of SRS-A. The anti-anaphylactic effect of budesonide and beclomethasone was also shown in sensitized guinea pigs pretreated with mepyramine, 2.5 mg/kg intraperitoneally, and challenged with nebulized ovalbumin. We suggest that the partial protection given by the corticosteroids budesonide and beclomethasone dipropionate is due to the inhibiton of SRS-A release.