Peptide hydrogels as mucoadhesives for local drug delivery.

We have investigated the possibility of using self-assembling peptide-based viscous solutions and hydrogels as mucoadhesives for the improved delivery of drugs to local mucosal surfaces. The stability of the samples under flow after deposition on a mucosal surface mimic was studied using a simplified in vitro model. Subsequently lidocaine and flurbiprofen, two commercial drugs, were incorporated into the viscous solutions and hydrogels and their release properties investigated using the same model. Peptide-based hydrogels showed a good resistance to erosion under flow conditions. Addition of the soluble drug (lidocaine at low pH) resulted in a stiffening of the samples but did not affect the overall peptide release. Although for this drug the conditions were not favourable, improved retention of the drug was observed for the stiffest samples tested. In the case of the insoluble drug (flurbiprofen) the samples mechanical properties were not altered when the drug was incorporated, however the sample stability and peptide release were. For mechanically weaker samples the presence of the drug as insoluble small particles resulted in an increase in their susceptibility to physically erode when a flow of medium was applied over its surface. On the other hand mechanically stronger samples showed an improved resistance to erosion, which resulted in enhanced drug retention.