Therapeutic systems and novel drug delivery devices can manipulate drug formulation to control drug release characteristics. This allows drugs to be released at predetermined rates and durations to maintain therapeutic drug concentrations and reduce side effects. Some examples of controlled release oral formulations include prolonged release, sustained release, extended release, and membrane-controlled, matrix-controlled, ion-exchange, and spansule systems. These systems aim to provide advantages like reduced dosing frequency and improved patient compliance compared to immediate release formulations.