The size and location of 
microsphere uptake / delivery are important determinants of the final 
biodistribution of oral 
microsphere systems. Formulations, kits, methods of administering the formulations, and using the kits are described herein. The formulations are oral dosage formulations. In one embodiment, the formulations contain microparticles and / or nanoparticles having a homogenous size range selected to optimize uptake in a specific region of the GI tract and 
target drug delivery to specific organs. In some embodiments, the dosage formulation contains an 
enteric coating and / or a magnetic material. In a preferred embodiment, the formulation contains a magnetic material and an 
active agent to be delivered, optionally the 
active agent is in the form of micro- or nano-particles. In some embodiments metallomucoadhesive materials and / or magnetic materials are employed as magnetic and / or mucoadhesive sources. Formulations containing magnetic materials can be localized using the kits and methods disclosed herein. In one embodiment, the method includes orally administering the formulation and applying an 
extracorporeal magnet to 
a site on the outside surface of the patient's body in an area that closely apposes the location in the 
gastrointestinal tract to which delivery of the formulation is desired. The 
extracorporeal magnet is applied for a suitable time period to allow for the 
drug to be released from the formulation and / or to allow for the formulation to adhere to the site. Both magnetic and mucoadhesive forces may be utilized to site-direct and retain the 
dosage form in the region of the gastrointestinal (GI) tract most suitable for the desired delivery.