The invention relates to pyridazinone and pyridone compounds having formula (I) or (I&prime；), and pharmaceutically acceptable salts, hydrates, and solvates thereof (I) wherein R1/R4 and X and X3 are as defined in the claims. The invention further relates to their use as inhibitors of copper-containing amine oxidases. The present invention also relates to the preparation of the aforementioned compounds and to pharmaceutical compositions comprising as an active ingredient(s) one or more of the aforementioned compounds, pharmaceutically acceptable salts, hydrates, or solvates thereof.
