72571-82-5 8-Ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acid 3H2-O Pipemidic acid trihydrate Pyrido(2,3-d)pyrimidine-6-carboxylic acid, 5,8-dihydro-8-ethyl-5-oxo-2-(1-piperazinyl)-, trihydrate