A PROCESS FOR THE PREPARATION OF A PHARMACEUTICALLY PURE POLYMORPHIC FORM I OF OLANZAPINE

摘要

The present invention relates to a process for the preparation of pharmaceutically pure polymorphic form I of olanzapine, which com-prises crystallization of olanzapine from a solution in methylene chlo-ride, wherein before the crystallization, said solution of olanzapine in methylene chloride is treated with silica gel, preferably at reflux tem-perature. Also disclosed is form I of olanzapine substantially free of im-purity S, as well as a process for removing of impurity S from olanzap-ine polymorphic form I.