Mucoadhesive Properties of Eudragit®RS100, Eudragit®S100, and Poly(ε-caprolactone) Nanocapsules: Influence of the Vehicle and the Mucosal Surface

The use of polymers as mucoadhesive materials has been explored in several drug delivery systems. It is well known that the resulting mucoadhesiveness not only depends on the polymers by themselves, but also on the way they are delivered and on the application target. However, little attention has been given to the combined effect of such characteristics. Therefore, the objective of this study is to analyze the mucoadhesion resulting from combined effects of nanocapsules produced with polymers of different ionic properties, Eudragit®RS100, Eudragit®S100, or poly(ε-caprolactone), when they are incorporated into different vehicles (suspension, hydrogel, and powder) and applied on different mucosal surfaces (mucin, porcine vaginal, and buccal mucosa). Mucoadhesion was measured by a tensile stress tester. Our findings show that polymeric self-assembling as nanocapsules improved the mucoadhesion of the polymers. Eudragit®RS100 nanocapsules have the best performance, independently of the vehicle and surface used. Regarding the vehicle, hydrogels showed higher adhesion when compared to suspensions and powders. When considering different types of surfaces, mucin presented a similar pattern like the animal mucosa, but it overestimated the mucoadhesiveness of all formulations. In conclusion, this study demonstrated that the best strategy to achieve high mucoadhesive formulations is by incorporating Eudragit®RS100 nanocapsules in hydrogels. Moreover, mucin is a suitable substrate to compare and screen different formulations but not as a conclusive estimation of the mucoadhesion values that can be achieved. These results are summarized in a decision tree that can help to understand different strategies of combination of these factors and the expected outcomes.