Polymeric nanoparticles for oral delivery of protein drugs

Proteins and peptides as therapeutic agents have been used for clinical applications. While due to their short in vivo half life, easily undergoing hydrolysis, low permeability to biological membrane barriers and poor stability in gastrointestinal tract, parenteral administration such as subcutaneous, intravenous, or intramuscular injections is the common way for these drugs delivery. Alternative injection, the oral route presents many advantages such as avoidance injection pain and discomfort, elimination of possible infections caused by the use of needles. Therefore, many strategies to improve their oral delivery efficiency have been studied. One of the most potential strategies is usage of micro- and nanoparticles of functional polymers as protein drug carriers. This chapter summarizes the nanoparticles based on different polymers as an oral administration system for protein and peptide drugs delivery. It primarily describes the pH-sensitive nanoparticles. Depending on the fact that pH of the human gastrointestinal tract increases progressively from the stomach to the intestine, nanoparticles remain insoluble in the stomach and disintegrate at the higher pH. Secondly, mucoadhesive polymer-coated nanoparticles are described, which can intensify the contact between the polymer and the mucus surface either by non covalent bonds or covalent disulfide bonds. Thirdly, bacteria degradable polymer-coated nanoparticles for colon delivery are briefly reported. Fourthly, a pH-sensitive and mucoadhesive polymer based on nano- and microparticles is included. Finally, some success of oral protein drug in vivo deliveries are enumerates. All of these nanoparticles can be expected to improve the proteins absorption.