The invention relates to a pharmaceutical composition comprising a plurality of controlled-release coated microparticles each comprising a floating core, on the surface of which is deposited a layer containing at least one active principle, said layer being covered with a controlled-release coating, characterized by the fact that said floating core is composed of cellulose acetate phthalate and has an apparent density of less than or equal to 0.6 g/mL and said coated microparticles have a density of less than or equal to 0.7 g/mL.