Multifunctional matrices for oral peptide delivery

The oral administration of peptide drugs represents one of the greatest cha llenges in pharmaceutical technology. To gain a sufficient bioavailability of these therapeutic agents, various barriers including the mucus-layer bar rier, the enzymatic barrier, and the membrane barrier have to be overcome. A promising strategy for achieving this goal is the use of multifunctional matrices. These matrices are based on polymers that display mucoadhesive pr operties, a permeation-enhancing effect, enzyme-inhibiting properties, and/ or a high buffer capacity Moreover, a sustained or delayed drug release can be provided by delivery systems that contain such polymers. Among them, po lyacrylates, cellulose derivatives, and chitosan are promising excipients t hat can also be customized by chemical modification to improve certain prop erties. For example, the covalent attachment of thiol moieties on these pol ymers leads to improved mucoadhesive and permeation-enhancing properties, a nd the conjugation of enzyme inhibitors enables the matrices to provide pro tection for peptide drugs against enzymatic degradation. The efficacy of mu ltifunctional matrices in oral peptide delivery has been verified by variou s in vivo studies that could pave the way for the development of commercial ly, viable formulations.