A new topical formulation for psoriasis: development of methotrexate-loaded nanostructured lipid carriers

The aim of the present work was to develop and assess the potential of nanostructured lipid carriers (NLCs) loaded with methotrexate as a new approach for topical therapy of psoriasis. Methotrexate-loaded NLCs were prepared via a modified hot homogenization combined with ultrasonication techniques using either polysorbate 60 (P60) or 80 (P80) as surfactants. The produced NLCs were within the nanosized range (274-298 nm) with relatively low polydispersity index (<0.25) and zeta potential values around -40 mV. NLCs demonstrated storage stability at 25°C up to 28 days. The entrapment efficiency of methotrexate in NLC-P60 and -P80 was ∼65%. Cryo-SEM images showed the spherical shape of the empty and methotrexate-loaded NLCs. FT-IR confirmed methotrexate presence within the NLCs. The in vitro release of methotrexate from the NLCs followed a fast release pattern reaching ∼70% in 2h. In vitro skin penetration study demonstrated that methotrexate-loaded NLCs-P60 had higher skin penetration when compared to free methotrexate, suggesting a significant role of drug-nanocarriers on topical administration. Methotrexate-loaded NLC-P60 provided drug fluxes of 0.88 μg/cm(2)/h, higher (P<0.001) than with the free drug (control, 0.59 μg/cm(2)/h). The results indicate the potential of NLCs for the delivery of methotrexate to topical therapy of psoriasis.