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A solid dosage formulation having a core with a pharmacological agent dispersed in a first controlled-release matrix from which release of the agent is relatively slow; and a coat formed over the core and having the agent dispersed in a second controlled-release matrix from which release of the agent is relatively fast. The first matrix can be a cross-linked high amylose starch and the second matrix can be a mixture of polyvinyl acetate and polyvinylpyrrolidone.