Effects of N-556 on experimental allergy models in rats.

The oral anti-allergic effect of 1,3-bis-(2- ethoxycarbonylchromon-5-yloxy)-2-((S)-lysyloxy)propane dihydrochloride (N-556, KY-556) was investigated. 1) N-556 (10-100 mg/kg, p.o.) inhibited dose-dependently the 48-hr homologous PCA in rats, and the duration of action was longer than that of intravenous DSCG. 2) N-556 (20 and 100 mg/kg once a day for 20 consecutive days, p.o.) tended to inhibit the histamine release from actively sensitized rat lung fragments. 3) N-556 (100 mg/kg, p.o.) showed the prolongation of survival time in the rat systemic anaphylaxis. 4) N-556 (100 mg/kg, p.o.) significantly inhibited the increased airway resistance in experimental asthma in rats. These results suggest that N-556 is a promising and orally-active pro-drug of disodium cromoglycate (DSCG) against allergic diseases.