Subject matter of the present invention is a white crystalline polymorph A of the Ca salt of a compound according to formula I or a solvate and/or a hydrate thereof with a molar ratio of a compound according to formula I or a solvate and/or a hydrate thereof to calcium which is 2±0.3. Subject matter of the present invention is in particular a compound according to formula I or a solvate and/or a hydrate thereof which is characterized by an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2theta at ±0.2 of the values shown below: 2 theta = 5.91 °, 9.64°, 16.78°, 17.81°, 19.81°, 25.41° In particular the invention refers to new polymorphs of calcium salts of the Ca salt of a compound according to formula I or a solvate and/or a hydrate thereof which inhibits dihydroorotate dehydrogenase (DHODH), a process for their manufacture, pharmaceutical compositions containing them and to their use for the treatment and prevention of diseases, in particular their use in diseases where there is an advantage in inhibiting dihydroorotate dehydrogenase (DHODH).
