Application of quality by design approach to formulate and optimize tripterine loaded in nanostructured lipid carriers for transdermal delivery

This paper aimed to formulate and optimize nanostructured lipid carriers (NLCs) formulation loaded with tripterine (TRI) for transdermal administration by employing Quality by Design (QbD) approach. NLCs loaded with TRI (TRI-NLCs) were prepared by emulsification evaporation method. The effect of critical parameters on critical quality attributes of NLCs was studied. Design space with favorable response values was defined. The optimized TRI-NLCs were characterized by morphology, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) analysis and in vitro properties. Further, a gel (TRI-NLCs-gel) was made by dispersing TRINLCs into carbopol 980 for transdermal delivery. Different drug administration methods and dermatokinetic study of TRI-NLCs-gel were carried out. The optimized TRI-NLCs possessed nanometric size and high entrapment efficiency. DSC and PXRD results showed TRI was completely incorporated in lipids. In vitro drug release result revealed the sustained release characteristics of TRI-NLCs. Different drug administration methods and dermatokinetic study revealed the rapid lose water of gel could enhance NLCs into deep skin layer. Histopathology study showed intact skin treated with TRI-NLCs-gel, indicating good biocompatibility of TRI-NLCs-gel. This investigation revealed that QbD design was crucial to understand the formulation process of NLCs, which was of great importance to guide the preparation of nano-scale pharmaceutical product.