Selection of excipients for Ethosome Formulations of Imiquimod through Drug–excipient Compatibility testing for Skin Cancer: A Pre-Formulation Study

Skin cancer is a prevalent global issue, with traditional therapies often lacking drug penetration and bioavailability. Ethosomes, lipid-based vesicles, offer a promising solution for transdermal drug delivery, encapsulating both hydrophilic and lipophilic drugs and providing superior skin penetration. Imiquimod, an immune response modifier, is commonly used to treat non-melanoma skin cancers, but its effectiveness is hindered by poor skin penetration and local irritation. Ethosomal formulations offer an innovative approach to improve the bioavailability and therapeutic effect of Imiquimod by facilitating deeper skin penetration and sustained release. The development of ethosomes requires the careful selection of excipients that are compatible with both the drug and the delivery system. In this study, Phosphatidylcholine, Ethanol, and Propylene Glycol were chosen as excipients for the formulation of Imiquimod-loaded ethosomes. Phosphatidylcholine serves as the key phospholipid for vesicle formation, while Ethanol and Propylene Glycol act as solvents and penetration enhancers. Imiquimod's compatibility with excipients was investigated utilizing methods such as DSC, FTIR, XRD, and UV to identify any possible interactions. The results confirmed that Imiquimod is compatible with Phosphatidylcholine, Ethanol, and Propylene Glycol, with no significant chemical interactions. This indicates the suitability of these excipients for the future development of Imiquimod-loaded ethosomal formulations for the treatment of skin cancer, ensuring both stability and enhanced therapeutic efficacy.