A preparation process of esomeprazole sodium substantially free of sulfone impurity including the steps of: a) combining either esomeprazole with a (C3-C8)-ketone or a mixture thereof a sodium alkoxide and a (C1-C5)-alcohol or esomeprazole sodium with a (C3-C8)-ketone or a mixture thereof and a (C1-C5)-alcohol; and b) recovering the esomeprazole sodium formed from the reaction media by filtration.

The present invention relates to a new process for the preparation of crystal modifications for use in the preparation of esomeprazole sodium salt. Further the present invention also relates to the use of the new crystal modifications for the treatment of gastrointestinal disorders pharmaceutical compositions containing them as well as the crystal modifications as such.