Abstract: The invention provides 1-cyclopropyl-6-fluoro-1,4- dihydro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-3- quinolinecarboxylic acid sesquihydrate with excellent stability represented by a following formula (1), ##STR1## and process for producing the same.

Abstract: Urea derivatives of the following formula: ##STR1## wherein R.sub.2 indicates a piperidino or pyrrolidino group which may be substituted with a hydroxy group or a lower alkyl group having 1 to 13 carbon atoms; A indicates an ethylene group, propylene group, butylene group or butenylene group; R.sub.2 indicates a straight or branched alkyl group having 1 to 20 carbon atoms, a benzyl group, or a phenyl group which may have 1 to 3 substituents such as a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 3 carbon atoms, a halogen atom, a trifluoromethyl group, an amino group, a nitro group or a methylenedioxy group; and X indicates an oxygen or sulfur atom, as well as the hydrates and pharmaceutically acceptable salts thereof are useful antiulcer agents.

Abstract: Urea derivatives of the following formula, ##STR1## wherein R.sub.1 indicates a piperidino group or pyrrolidino group which may be substituted with hydroxy group or lower alkyl group having 1 to 3 carbon atoms; A indicates an ethylene group, propylene group, butylene group or butenylene group; R.sub.2 indicates a straight or branched alkyl group having 1 to 20 carbon atoms, cycloalkyl group having 3 to 6 carbon atoms, benzyl group, or phenyl group which may have 1 to 3 substituents such as lower alkyl group having 1 to 6 carbon atoms, lower alkoxy group having 1 to 3 carbon atoms, halogen atom, trifluoromethyl group, amino group, nitro group or methylenedioxy group; X indicates an oxygen or sulfur atom, the hydrates and pharmaceutically acceptable acid addition salts thereof are useful as antiulcer agents.