Water-soluble forms of a series of 1-alkyl(aryl)imidazole-4,5-dicarboxylic acids were prepared. Anticonvulsant activity of 1-propylimidazole-4,5-dicarboxylic acid and its triethanolammonium salt was studied using the NMDA-induced convulsion model. The triethanolammonium salt of 1-propylimidazole-4,5-dicarboxylic acid was shown to possess anticonvulsant activity whereas the acid itself was a convulsant. The change of pharmacological profile was related to the formation of ion pairs or associates even in polar physiological media. The ability to associate was confirmed using conductivity measurements. An x-ray crystal structure analysis was performed for the triethanolammonium salt of 1-propylimidazole-4,5-dicarboxylic acid.