Oral thin film dosage form of a stable dispersion of non-solubilized amorphous or partially amorphous active agent(s), having a mean particle size diameter D50 equal or less than 250 μm, that remains uniformly distributed within a film matrix and contains at least one film forming polymer, and optional pharmaceutically-acceptable excipients, such as diluents, plasticizers, surfactants, sweeteners, and taste-masking agent(s), are prepared by a process including first providing the active agent in an amorphous particle form having a mean particle size diameter D50 equal or less than 250 μm. Next, the active agent is suspended in a liquid film-forming formulation without dissolving the active agent. Therefore, the solvent is removed to form a film.