Can nanoparticles be used for oral drug delivery?

Polymeric nanoparticles are currently under preclinical evaluation for oral administration. In general, the delivery of peptides, oligonucleotides, and macromolecular drugs by oral administration involves overcoming several challenges as compared with parenteral administration. The pH values of the stomach and intestine ranged from 1 to 8. At low pH, biological agents can undergo oxidation or hydrolysis to lose their activity. In addition, unprotected drugs can be degraded by enzymes and proteases in the gastrointestinal tract. Encapsulation of the drug in a polymer nanocarrier protects the drug from these obstacles. Another important obstacle is drug penetration of the intestinal mucosal barrier. Modification of the nanoparticle surface with PEG can help the nanoparticles penetrate the mucosal barrier. Currently, mucosal adhesive polymers, such as chitosan, polyacrylic acid, and block copolymers, have been used to improve intestinal absorption. Furthermore, by using terminal functionalized polymers to send group functionalized polymers, it is possible to convert polymer nanoparticles into target cells that promote transcytosis.