Effect of glycerol on the physical and mechanical properties of thin gellan gum films for oral drug delivery

In this work, deacylated gellan gum and the plasticizer glycerol were used as primary components for the preparation of thin films intended for the oral delivery of therapeutic molecules. The samples were prepared by a solvent casting method and characterized for their thickness, tensile properties, swelling ability, mucoadhesion capacity and uniform drug distribution. The amount of glycerol was varied from 20% to 75% w/w in order to obtain films with tunable mechanical properties and high drug loading efficiency. The addition of glycerol was able to positively influence the mechanical characteristics of gellan gum thin film overcoming the brittleness caused by the rigid interconnection among the polymeric chains. Plasticized gellan gum films containing 50% w/w of glycerol showed optimal mechanical resistance and mucoadesion capacity, which were adversely affected by the inclusion of higher concentrations of glycerol. On the contrary, only high amounts of the plasticizer (⩾ 70% w/w) enabled a homogeneous distribution of the model drug fluconazole within the polymeric matrix. Overall these results indicate that gellan gum-based thin films can be potentially used for buccal drug delivery upon precise selection of the appropriate concentration of glycerol used as a plasticizer.