A pharmaceutical formulation includes (1) a first dosage component comprising: a core comprising a non-ionic polymer matrix, a first amount of ondansetron or an equivalent amount of an ondansetron salt thereof dispersed within the matrix, and an electrolyte dispersed within the matrix； a first seal coat surrounding the core, the first seal coat comprising a non-ionic polymer matrix； and an immediate release drug layer surrounding the first seal coat, wherein the immediate release drug layer comprises a non-ionic polymer and a second amount of ondansetron or an equivalent amount of an ondansetron salt thereof dispersed therein； and (2) a second dosage component comprising: a core comprising a third amount of ondansetron or an equivalent amount of an ondansetron salt thereof, at least one filler, and a lubricant； and a coating surrounding the core, the coating comprising water and a mixture of methacrylic acid-alkyl acrylate copolymers with alkaline groups.
