The use of chitosan as cationic coating or gel vehicle for polymeric nanocapsules: Increasing penetration and adhesion of imiquimod in vaginal tissue.

The human papillomavirus (HPV) infection, which is strongly related to cervical cancer, can be reduced by the topical application of imiquimod. Some strategies have been used to increase the adhesion and penetration of drugs through the vaginal mucosa. Two of them are the development of mucoadhesive semisolid formulations and the development of polymeric nanocarriers. In this paper, we hypothesize that the combined use of these two strategies results in a better performance of the formulation to retain imiquimod into the vaginal tissue. Aiming this, two different systems are proposed: (a) chitosan-coated poly(ε-caprolactone)-nanocapsules incorporated into hydroxyethylcellulose gel (HEC-NC), and (b) poly(ε-caprolactone)-nanocapsules incorporated into chitosan hydrogel (CHIT-NC). These formulations were submitted to three main tests: mucoadhesivity by interaction, permeation and washability test (or retention test). We developed an integrative index that allows comparing the global performance of the proposed formulations by considering jointly the results of these three tests. Thus, when considered the integrative indexes for the formulations, our results show that CHIT-NC presents the best performance for the treatment of HPV.