Preparation and evaluation of hydroxypropyl methylcellulose-based film incorporated with aspirin-loaded solid lipid nanoparticles to treat skin cancer

The purpose of this study was to develop a hydroxypropyl methylcellulose (HPMC)-based thin film incorporating aspirin (ASP)-loaded solid lipid nanoparticles (SLNs) for skin cancer therapy. SLNs are allowed to effectively interact with the intercellular lipids in the stratum corneum, leading to a continuous release of ASP. Thin films based on HPMC, a mucoadhesive polymer, can improve the skin residence time of SLN. ASP, a biopharmaceutics classification system (BCS) class I drug, was encapsulated into SLNs using the water-in-oil-in-water (W/O/W) emulsion method. Among tested SLN formulations, the one utilizing stearic acid, Span 80, and poloxamer 188 exhibited the smallest particle size (111.80 nm) and highest loading efficiency (67.40%). The HPMC-thin film with 10% SLNs showed sustained ASP release and significant anti-cancer effects. In cytotoxicity studies on skin cancer cells, the half maximal inhibitory concentration (IC₅₀) values for ASP solution, SLNs, and the HPMC-thin film with SLNs were 0.23, 0.15, and 0.18 mM, respectively. This means that the anti-cancer effect of ASP was enhanced by approximately 1.55 times (SLNs) and 1.28 times (HPMC-thin film with SLNs) compared to the ASP solution. These results indicate that the HPMC-based thin film with ASP-loaded SLNs could be useful as a skin cancer treatment agent.