A unit dose sustained-release oral dosage form containing a plurality of melt-extruded particles, each consisting essentially of a therapeutically active agent, one or more retardants, and an optional water-insoluble binder is disclosed. The particles have a length of from about 0.1 to about 12 mm and can be of varying diameters and each unit dose provides a release of therapeutically active agents over at least about 8 hours. Methods of preparing the unit doses as well as extrusion processes and methods of treatment are also disclosed.