Formulations for oral controlled release dosage comprising a core and one or more barrier layers

A solid oral dosage formulation of controlled release multilayer comprising (a) a core comprising one or more active ingredients and one or more enteric materials; and (b) two or more barrier layers, one above the core and below the core, comprising one or more swellable, erodible or gellable polymers; and in which, after administration to a subject, the active substance is released with an increase in the release rate in response to changes in pH as the dosage formulation drops the GI tract.