Bilayer chitosan-based patches for steroidal drug delivery on the oral mucosa

Clobetasol-17-proprionate (CP) is the most potent, highly lipophilic topical corticosteroid, used for the treatment of immune-mediated muco-cutaneous diseases. No commercial preparations are available for the oral cavity and galenic formulations are often ineffective due to the easy displacement by saliva and muscular movements. Here, we developed and characterized novel mucoadhesive patches for CP delivery on the oral mucosa. Bilayer chitosan (CS)-based mucoadhesive patches (CS-CP) were produced via electrophoretic deposition (EPD) and characterized for physical and biological properties. Bilayer CS-CP patches showed a porous structure at the surface towards the oral mucosa (containing CP) and a more compact occlusive backing layer (without CP). CSCP patches displayed fast swelling (301.6 +/- 0.8 %) in PBS, while a sustained CP release was observed over time, both in vitro in PBS and using an ex vivo model of porcine oral mucosa, with about 40 % of CP released after 6 h. CP did not affect the mucoadhesive properties of the patches. Through a 3D model of the oral mucosa, the patches' cytocompatibility and the activity of CP released in regulating immune response-related pathways were evaluated. CS-based patches represent innovative biocompatible biomedical devices for the oral mucosa, able of successfully loading highly lipophilic drugs, including CP.