Development of bilayer films based on shellac and esterified cellulose nanocrystals for buccal drug delivery

Bilayer films were fabricated based on natural-based and biocompatible polymers such as esterified cellulose nanocrystals (ECNCs) and shellac, aiming for use in buccal drug delivery. Baicalin was used as the model drug. The swelling properties, drug loading and mechanical properties of films were evaluated and further characterized for mucoadhesion and in vitro drug release properties. The film (F2) containing ECNCs 45%, shellac 25% and polyethylene glycol 30% shows the best properties for the development of the film formulation. The swelling capacity of films was in the range of 36.5 +/- 4.1-279.2 +/- 14.1%. In vitro drug release shows that anomalous transport behavior indicates that transport includes drug diffusion and polymer relaxation. For film F2, the tensile strength and adhesion strength reaches to the maximum value of 21.57 +/- 0.83MPa and 0.073 +/- 0.004N, respectively. The interfacial interactions between drug and film components were confirmed by FTIR and XRD.