Pharmaceutical composition containing poly(bile) acid (PBA) polymers for oral delivery of agent(s) show enhanced uptake by the pancreas, liver, and colon. These nanoparticles show significant retention in the pancreas and colon and are therefore useful for selective delivery. The examples demonstrate efficacy of oral administration of insulin to treat diabetes, and oral induction of tolerance by administration of insulin or ovalbumin in combination with rapamycin. Diabetic animals treated with the insulin or insulin with rapamycin showed normalization of blood glucose levels.
