"Advancements in Transdermal Drug Delivery Using Ionic Liquids: Design Strategies, Functional Roles, Mechanisms, and Future Challenges"

-One potential method for improving transdermal medication absorption is ionic liquids (ILs). However, further research is necessary to create effective ILs and clarify their methods of action because of the unique structural characteristics of ILs. This paper examines the basic design concepts of ideal ILs for transdermal drug delivery systems (TDDS), taking into account toxicity, skin permeability, and melting point, all of which are influenced by ion types, molar ratios, functional groups, and inter-ionic interactions. The functions of ILs in developing TDDS are also described in detail, including their use as novel solvents to improve drug solubility in carriers, as innovative skin penetration enhancers to increase transdermal drug absorption, as new active pharmaceutical ingredients (API-ILs) to control drug pharmacokinetics, skin permeability, solubility, and release, and as sophisticated polymers to develop smart medical materials. Additionally, a summary of several action pathways is provided, mainly focusing on the interactions between ILs, medications, polymers, and skin constituents. The discussion concludes with a discussion of ILs' future challenges, including determining quantitative structure-activity relationships, comprehending the intricate forces of interaction between anions, medications, polymers, and the skin microenvironment, guaranteeing long-term stability, and resolving in vivo safety issues. In conclusion, the purpose of this essay is to encourage the development of TDDS with ILs.