The actions of F 1865 (ethyl 4' methoxy 4 phenyl thiazolyl 2 oxamate), an inhibitor of the release of histamine from mast cell, desonide, a corticosteroid, mepyramine maleate, an anti-H1 antihistaminic, and disodium cromoglycate were compared after cutaneous application in various experimental models of allergy and inflammation. F 1865 decreased IgE- and IgG-dependent passive cutaneous anaphylaxis in rats at doses having no effect on histamine- and serotonin-induced capillary permeability. Disodium cromoglycate showed the same activity spectrum, but its action was only found after intradermal application. The reduction of cutaneous anaphylaxis by desonide was found parallel to its inhibition of histamine effects, and to a lesser extent of serotonin effects. In the case of mepyramine, the antiallergic effect may be explained by its antihistaminic action. Desonide was highly active on cantharidin-induced non-immune inflammation and on non-immune and delayed hypersensitivity reactions induced by picryl chloride in mouse ear. Although far less active than the corticosteroid, F 1865, mepyramine and disodium cromoglycate did reduce the three types of reactions in mice. This evidenced a part played by histamine in such inflammations. Then it is likely that the inhibition of histamine release by F 1865 plays an important part in the effect of the compound observed in the various inflammations studied. However we cannot exclude actions against other mediators involved in these reactions.
