Chitosan Hydrogel Containing Capsaicinoids-Loaded Nanocapsules: An Innovative Formulation for Topical Delivery

The aim of the present work was to develop and characterize a chitosan hydrogel containing capsaicinoids-loaded nanocapsules intended for topical delivery. Such system is promising since it brings together the skin bioadhesion and film forming capability of chitosan and the control of the drug release due to the reservoir property of the nanocapsules. The hydrogels showed pH values between 4.2 and 4.4, suitable for topical administration, as a consequence of lactic acid in the formulations. The consistence values (Pa.sn) /flow indexes (n = dimensionless) were 19.64 +/- 2.61/ 0.76 +/- 0.03 and 13.12 +/- 0.93/0.82 +/- 0.01 for the gels containing the nanocapsule suspension or exclusively water, respectively, demonstrating the effect of the nanocapsules on the slight increase of the gel consistence. The nanocapsules may also interfere in the interaction between chitosan chains and in the polymer network. The pseudoplastic behavior of the hydrogels did not change after the incorporation of nanocapsules. The release study showed a more controlled release of capsaicin and dihydrocapsaicin from the hydrogel containing nanocapsules comparing with the hydrogels containing free capsaicinoids. This chitosan hydrogel containing drug-loaded nanocapsules is likely interesting when a controlled release is intended.