In our current research, sucrose palmitate (SP) was applied as a possible permeation enhancer for buccal use. This route of administration is a novelty as there is no literature on the use of SP in buccal mucoadhesive films. Films containing SP were prepared at different temperatures, with different concentrations of SP and different lengths of hydroxypropyl methylcellulose (HPMC) chains. The mechanical, structural, and in vitro mucoadhesive properties of films containing SP were investigated. Tensile strength and mucoadhesive force were measured with a device and software developed in our Institute. Positron annihilation lifetime spectroscopy (PALS) and X-ray powder diffractometry (XRPD) were applied for the structure analysis of the films. Mucoadhesive work was calculated in two ways: from the measured contact angle and compared with direct mucoadhesive work, which measured mucoadhesive force, which is direct mucoadhesion work. These results correlate linearly with a correlation coefficient of 0.98. It is also novel because it is a new method for the determination of mucoadhesive work.

Nowadays, the buccal administration of mucoadhesive films is very promising. Our aim was to prepare ascorbic acid-containing chitosan films to study the properties and structures important for applicability and optimize the composition. During the formulation of mucoadhesive films, chitosan as the polymer basis of the film was used. Ascorbic acid, which provided the acidic pH, was used in different concentrations (2–5%). The films were formulated by the solvent casting method. The properties of films important for applicability were investigated, such as physical parameters, mucoadhesive force, surface free energy, and breaking strength. The fine structure of the films was analyzed by atomic force microscopy, and the free volume was analyzed by PALS, which can be important for drug release kinetics and the location of the drug in the film. The applicability of the optimized composition was also tested with two different types of active ingredients. The structure of the films was also analyzed by XRPD and FTIR. Ascorbic acid can be used well in chitosan films, where it can function as a permeation enhancer when reacting to chitosan, it is biodegradable, and can be applied in 2% of our studies.