In this study, self-assembling Soluplus^® micelles were examined for inherent properties. Through calorimetric analysis, the critical micelle concentration (CMC) could be determined at 25 and 37 °C, and the influence of three media (Milli-Q water, phosphate-buffered saline (PBS) with a pH of 7.4 and 0.1 M HCl) on the lower critical solution temperature (LCST) was detected. Furthermore, the solubilisation of a poorly soluble drug, furosemide, into the Soluplus^® micelles was studied. The concentration-dependent properties of the micellar system were assessed through an examination of the micellar size, polydispersity, morphology, viscosity and solubilising properties, which were all found to be affected by the concentration, but temperature, pH and the composition of the test medium were also found to have an effect. Homogeneity in the estimated micellar size and morphology was shown for monophasic micelle dispersions in lower concentrations and with a shift towards more complex structures or aggregates in higher concentrations. The micelles were further investigated in terms of drug release and biocompatibility with mucus-producing HT29-MTX cells, where no biocompatibility issues were found. In this research, the implications for oral drug delivery are discussed and valuable preformulation information is provided on the micellar properties of a Soluplus^® drug system in a liquid or semi-solid form.

From a patient-centric perspective, oromucosal drug delivery is highly attractive due to the ease of administration without the need of swallowing, and improved patient safety. The aim of the presented work was to prepare a buccal film using a self-forming micellar drug solubiliser as the film matrix, combining it with a mucoadhesive polymer for an enhanced retention on the buccal mucosa. Specifically, we propose the use of a graft co-polymer (Soluplus®), as a solubiliser and film former, supplemented with polymers with more hydrophilic properties and known mucoadhesive properties; hydroxypropyl methylcellulose (HPMC) or modified hydroxypropyl pea starch (Lycoat®). The film was manufactured by the solvent casting method. The resulting dual polymer film containing HPMC exhibited resistance to erosion and mucoadhesive properties superior to the control films of single polymers. In an in vitro oral cavity model, these properties were shown to correlate with increased residence time on simulated oral mucosa. Furthermore, all films containing the graft co-polymer showed similar permeability characteristics of furosemide towards buccal TR146 epithelial cells. This work illustrated that it is possible to manufacture dry, solid, dual polymer films containing an advanced drug delivery system with a cheap and simple method. The combination of a graft co-polymer with a mucoadhesive polymer transform into drug solubilising micelles in a mucin-retentive hydrogel scaffold with longer retention time on buccal mucosa for safe and enhanced advanced formulation.