Recent advances in biotechnology and genetic engineering have made the mass production of therapeutic biomacromolecules feasible, such as protein and peptide drugs.Although oral administration is considered to be the most convenient and preferred choice for patients, these biomacromolecular drugs are susceptible to both inactivation in the harsh pH environment of gastro-intestinal tract and degradation by proteolytic enzymes.Additionally, their highly hydrophilic character as well as large size lead to poor permeability across intestinal biological membranes.