Methods and devices for providing prolonged drug therapy

A method for treating Attention-Deficit Hyperactivity Disorder in a subject comprising:

• administering to said subject an osmotic dosage form comprising
• a capsule-shaped longitudinally compressed tablet core containing a plurality of layers wherein drug is contained in at least one layer and at least one other layer comprises a suitable fluid-expandable polymer, wherein said drug comprises methylphenidate hydrochloride;
• a semipermeable wall that surrounds said longitudinally compressed tablet core to form a compartment that has an osmotic gradient that drives fluid from an external fluid environment contacting said semipermeable wall into said compartment;
• and
• an orifice that is formed through said semipermeable wall at a location adjacent to the first layer that permits drug to be released from the compartment into said external fluid environment,
• wherein the dosage form releases the drug over a period comprising a first, second, and third sequential time intervals of equal duration, and
• wherein the dosage form releases more of said drug during said second interval than during said first interval and more of said drug during said third interval than during said second interval.