The present invention provides an oral medicinal composition for patients undergoing peritoneal dialysis, which is to be used for preventing an increase in carbonyl compounds and/or advanced glycation end-products (AGEs) in the abdominal cavity and peritoneum tissue after intraperitoneally administration of a glucose-containing peritoneal dialysis fluid. Said oral medicinal composition comprises, as the active ingredient, a pharmaceutically acceptable salt of pyridoxamine.
