Effect of carbenoxolone on prostaglandin synthesizing and metabolizing enzymes and correlation with gastric mucosal carbenoxolone concentrations.

Carbenoxolone in a dose dependent manner inhibits the activity of the prostaglandin (PG) metabolizing enzymes 15-hydroxy-PG-dehydrogenase and delta 13-PG-reductase in vitro, while this drug in the same dose range does not influence gastric mucosal PG synthesis by a microsomal cell fraction. Using a radioimmunoassay for carbenoxolone determination, we could show that during absorption high levels of the drug are reached within the gastric mucosa of human volunteers and gastric ulcer patients. From the tissue levels reached it seems possible that carbenoxolone inhibits PG inactivating enzymes of gastric mucosa in vivo as it does in vitro. Thus, decreased inactivation cytoprotective PG synthesized within the gastric mucosa, might contribute to the ulcer healing effect of carbenoxolone.