NEW MATERIAL:The cyclic anthranylic acid carboxylic acid derivative of formula I [R1 is H, carboxy, 1-3C alkoxycarbonyl or phenyl; R2 and R4 are independently H, 1-3C alkyl or benzyl; R3 is H, halogen, nitro, amino, cyano, carbamoyl, carboxy, 1-4C alkanoylamino, benzoylamino, 1-3C alkylsulfonylamino or (methyl-substituted) phenylsulfonylamino], its acid addition salt and their alkali metal salt.

EXAMPLE: 5,6-Dihydro-1,2-dioxo-4H-pyrrolo[3,2,1-ij]quinoline-6-carboxylic acid methyl ester.

USE: Anti rheumatics, treating agent for autoimmune diseases and medicine and preventive for metabolic osteopathy.

PREPARATION: The compound of formula III which is one of the compound of formula I can be produced by hydrolyzing the compound of formula II and acid carbonylating the product optionally in the presence of an oxidizing agent.