Diffusion-controlled dosage form and method of fabrication including three dimensional printing

A method of making a diffusion controlled release dosage form comprising a printed shell and a printed core, the method comprising:

• depositing a layer of a powder comprising particles of a release-blocking polymer which is substantially insoluble in water at room temperature but soluble in another solvent, and particles of a release-regulating polymer;
• depositing onto the powder in selected places a pattern of a shell binder liquid which comprises a solvent for the release-blocking polymer, thereby forming a portion of the printed shell wherein the powder particles are bound to each other;
• depositing onto the powder in selected places a pattern of an Active Pharmaceutical Ingredient-containing liquid, thereby forming a portion of the printed core wherein the powder particles are bound to each other by Active Pharmaceutical Ingredient;
• repeating the above steps enough times to manufacture a desired shape, wherein the shell binder liquid and the API-containing liquid differ;
• allowing the dosage form to dry;
• and
• separating unbound powder from the dosage form to provide a diffusion controlled release dosage form comprising a printed core and printed shell;
• wherein the core includes the same release-blocking polymer and the same release-regulating polymer as contained in the shell, and wherein the core has a core ratio of release-blocking polymer to release-regulating polymer in the core and the shell has a shell ratio of release-blocking polymer to release-regulating polymer in the shell, and the core ratio is substantially the same as the shell ratio.