The use of multifunctional polymers for non-invasive peptide and protein application

For the efficient delivery of peptide and protein drugs by non-invasive routes various strategies have been pursued to overcome enzymatic and mucosal barriers to gain sufficient bioavailability. Among such delivery systems multifunctional polymers have received considerable attention, which is reflected by numerous publications and patents. They are able to provide a controlled release for therapeutic peptides and proteins being embedded in the polymeric network either based on a simple diffusion process or on the biodegradation of the carrier matrix. Additionally, polymers such as polyacrylates display an inhibitory effect towards various proteases located on the absorption membrane. In combination with enzyme inhibitors, this protective effect towards enzymatic attack may further be improved. Moreover, polyacrylates and chitosan display a permeation enhancing effect, in particular for the paracellular uptake of peptide drugs from mucosal tissues. If these polymers also exhibit mucoadhesive properties, the concentration gradient of the drug on the mucosa can be increased and in the case of oral delivery the presystemic enzymatic degradation of the (poly)peptide drug in the intestine between the delivery system and the absorption membrane can be reduced. Delivery systems utilising multifunctional polymers include formulations such as nano- and microspheres, pellets and matrix-tablets.