The
antiallergic activity of
sodium 10-(2,3-dimethyl pentanamido)-4-oxo-4H-pyrimido [1,2-C] quinazoline-3-carboxylate-hydrate (
FR50948) was studied and compared with the activities of
sodium cromoglycate (SCG) and
lodoxamide.
FR50948 had inhibitory effects on type I and type III
allergic reactions, but not on type II and IV
allergic reactions.
FR50948 also had weak inhibitory effects on
inflammation (
carrageenin paw
edema and
adjuvant arthritis) and SRS release from rat neutrophils, but no antagonistic effects to
histamine and
serotonin. The inhibitory effect of
FR50948 on
IgE-mediated type I
allergic reactions was essentially the same as those of SCG and
lodoxamide, because
FR50948 inhibited the histamine release from rat peritoneal mast cells and had cross tachyphylaxis with SCG in the rat PCA test. However,
FR50948, like
lodoxamide, had a stronger activity than SCG and was effective by the oral route, unlike SCG which was effective only by the parenteral route. Furthermore, the inhibitory effects of
FR50948 on type III reactions and inflammatory reactions were much more potent than those of SCG and equal to those of
lodoxamide, and the effect on
IgG-mediated PCA was stronger than that of either reference
drug. These results suggest that
FR50948 will be beneficial in clinical use.