(3Z)-2,3-Dihydro-3-[[[4-[methyl[2-(4-methyl-1-piperazinyl)acetyl]amino]phenyl]amino]phenylmethylene]-2-oxo-1H-indole-6-carboxylic Acid-D3 is an intermediate used in the synthesis of Nintedanib Demethyl-O-glucuronic Acid-d3 (N478297), which is an isotopic analog of Nintedanib Demethyl-O-glucuronic Acid (N478295), a metabolite of the drug Nintedanib (N478290).