US Patent 7572463 Oral dosage forms

A controlled-release oral dosage formulation of a salt-forming active ingredient, wherein the active ingredient is present as at least two different salts in a solid aggregation state, wherein the two different salts have different water solubility and release the active ingredient in-vitro at different release rates, provided that oral dosage formulations are excluded which comprise a resin carrying a sulfonate group and a resin carrying a carboxyl group and which contain an active ingredient in a form fixed to these resins.