PH INDEPENDENT EXTENDED RELEASE PHARMACEUTICAL FORMULATION

Pharmaceutical formulations of acidic pharmacologic agents which demonstrate improved uniformity of release over the wide range of pH values encountered between the stomach and intestinal tract comprise an acidic pharmacologic agent dissolved or dispersed in a matrix comprising about 10 weight percent to about 40 weight percent of a neutral water-swellable hydrophilic polymer and 20 weight percent to about 50 weight percent of an acid-soluble polymer whic h swells in water at pH values above about 5. A particularly preferred formulation comprises divalproex sodium. Also disclosed are pre-tablet granulations and process for preparing both the pre-tablet granulation and t he tablet unit dosage form.