A comparative study between nanostructured lipid carriers and invasomes for the topical delivery of luteolin: Design, optimization and pre-clinical investigations for psoriasis treatment

Psoriasis is an inflammatory skin condition manifested by hyper-proliferation and reactive aberrant epidermal differentiation, in which genetic and environmental factors have a significant role. The current context is focused on designing novel nanovesicular systems (invasomes) incorporating terpenes with reported anti-inflammatory potential and loaded with a nutraceutical compound (luteolin/Lut) for treatment of psoriasis. Additionally, their topical efficacy in psoriasis treatment compared to lipid-based nanocarriers (nanostructured lipid carriers) was investigated. Invasomes were assessed regarding their particle size (PS), zeta potential (ζ-potential), drug entrapment (EE%), storage stability, in-vitro drug release profile and release kinetics. The optimized vesicles were investigated for their ex-vivo skin deposition and in-vitro anti-inflammatory potential in comparison with nanostructured lipid carriers (NLCs). The optimized formulation was selected to carry out the in-vivo study using rat model of imiquimod-induced psoriasis. Luteolin-invasomes were found to have spherical shape and promising colloidal properties. They possessed PS ranging from 277.80 to 812.91 nm, negative ζ-potential (-35.22-38.55 mV), and high EE% values, which ranged from 89.38 to 99.75 %. Furthermore, they exhibited good stability properties and significant sustainment of drug release in comparison to NLCs. In addition, they were able to enhance Lut deposition by 2.1-fold in the stratum corneum (SC) and 5.5-fold in epidermis and dermis compared to control suspension of Lut. Moreover, invasomes showed more potential to retain Lut into deep skin layers 1.5-fold higher than NLCs. They also displayed higher in-vitro anti-inflammatory activity compared to plain invasomes and control suspension, and comparable activity compared to NLCs. In the in-vivo animal study, the ability of Lut to alleviate psoriatic symptoms was significantly enhanced after its encapsulation in invasomal dispersions, where Lut-invasomes possessed a great inhibitory potential compared to the control Lut suspension, and even to Lut-NLCs. This suggests their efficiency in treating psoriasis, delineating them promising for further use in treating other inflammatory skin conditions.