Patent ID: 7320985

Claim:
A method for stabilizing an arylcarboxylic acid or a pharmacologically acceptable salt thereof in an aqueous solution, which comprises adding a pyridonecarboxylic acid selected from (a) a pyridonecarboxylic acid of the formula (IV): wherein X is a carbon atom; and R 12 , R 13 , R 14 and R 15 are the same or different and each is a hydrogen atom, a halogen, a carboxyl group, an optionally substituted lower alkyl group, an optionally substituted cycloalkyl group, an optionally substituted acyl group, an optionally substituted aryl group or an optionally substituted heterocyclic group; wherein R 12 and R 13 optionally form a 4- to 6-membered heterocyclic group with the adjacent nitrogen atom and X, and R 14 and R 15 optionally form a 4- to 6-membered heterocyclic group with the adjacent carbon atom, (b) cinoxacin or (c) sparfioxacin, or a pharmacologically acceptable salt thereof, to an arylcarboxylic acid of the formula (I): L 1 -R 1 COOH (I) wherein L 1 is an optionally substituted aryl group having not more than 14 carbon atoms; and R 1 is an optionally substituted alkyl group having not more than 4 carbon atoms or a single bond, or a pharmacologically acceptable salt thereof.