Nanoparticles enhance therapeutic outcome in inflamed skin therapy

Inflammatory reactions of the skin are a major therapeutic field; however, drug delivery is nowadays only related to the use of classical formulations like ointments and creams. Here, we report the behaviour of polymeric submicron particles (NP) for selective drug delivery to the inflamed skin. NPs of nominal diameters from 50 to 1000 nm were administered to an experimental dithranol-induced dermatitis inflammation model in mice ears. The results revealed that smaller particles had an around 3-fold stronger and deeper penetration tendency with a preferential accumulation in inflamed skin hair follicles and sebaceous glands (2.8 ± 0.6% and 2.3 ± 0.4% for NP100 and NP50 compared to 0.84 ± 0.04% and 0.92 ± 0.02% for the same sizes on healthy skin). Betamethasone loaded NP confirmed the size dependency by being therapeutically more efficient from histological examination and measurement of different inflammatory markers in the skin (myeloperoxidase activity of untreated control, 1.2 ± 0.4; NP1000, 1.0 ± 0.4; NP100, 0.5 ± 0.2, all U/mg). This approach holds a high potential for a selective therapy to the inflamed skin by increasing the local intradermal availability with simultaneous reduction in systemic adverse effects.