Investigating superiority of novel bilosomes over niosomes in the transdermal delivery of diacerein: in vitro characterization, ex vivo permeation and in vivo skin deposition study

Skin is considered the most accessible organ of the body because of its underlying capillary network. However, stratum corneum (SC), the upper most layer of skin, represents major diffusional barrier for most drugs. Hence, the use of edge activators (EAs) in designing novel elastic vesicles is hypothesized to impart their lipid bilayer with ultra-flexibility to trespass SC by high self-optimizing deformability. To confirm this hypothesis, this work aimed at developing novel bilosomes by modulating conventional niosomal composition using different bile salts as EAs and investigating their superiority over niosomes for transdermal delivery of diacerein (DCN), as model drug. Bilosomes were prepared by thin film hydration (TFH) technique according to full 3(1).2(2) factorial design to select the optimal formulation using Design-Expert((R)) software. The optimal bilosomes (B6) showed nanosized vesicles (301.65 +/- 17.32nm) and 100.00 +/- 0.00 % entrapment efficiency. Ex vivo permeation studies and in vivo evaluation revealed that B6 exhibited superior permeation and drug retention capacity compared to the conventional niosomal formulation and drug suspension. Furthermore, B6 was subjected to in vivo histopathological study using male Wistar rats which ensured its safety for topical application. Overall, the results confirmed the hypothesized superiority of bilosomes over niosomes for enhancing DCN flux across the skin.