There is provided a pharmaceutical dosage unit comprising an outer housing defined by an outer wall, one or more inner housings within the outer housing defined by one or more inner walls, a first antibiotic composition housed within the outer housing, a second antibiotic composition housed within the or one of the inner housing(s) wherein said outer wall is adapted to disintegrate or partially disintegrate within the small intestine of a mammal, releasing the first antibiotic compositions and wherein said inner wall(s) are adapted to disintegrate or partially disintegrate within the large intestine of a mammal, in particular the colon of the mammal, releasing the second antibiotic composition. There is also provided a dosage unit for use in therapy, in particular, infections of the GI tract.
