SOLID FORMS OF THE MAGNESIUM SALT OF (S)-OMEPRAZOLE AND PROCESSES FOR THEIR PREPARATION

New solid forms of the active ingredient magnesium salt of S-omeprazole, obtainable by a preparation process that comprises: a) crystallizing a magnesium salt of S-omeprazole from a solution of a magnesium salt of S-omeprazole in a solvent system that comprises a mixture of methanol/water with an amount of water equal to or greater than 0,01 ml/g of the magnesium salt of S-omeprazole starting material; b) isolating the magnesium salt of S-omeprazole that appears in the prior step; c) separating the free organic solvent from the magnesium salt of S-omeprazole obtained or, alternatively, separating both the free solvent and the solvation solvent. The new solid forms are obtained by a reproducible and robust process, with high yield and elevated optical purity, which is useful for the preparation of pharmaceutical products that contain said active ingredient.