Nucleic acid drugs, including antisense oligonucleotides (ASOs), have received considerable attention as novel therapeutics for the treatment of intractable diseases. Despite their potential benefits, ASOs are currently administered via injection, which can negatively impact patient quality of life because of the prevalence of severe injection site reactions. Non-invasive transdermal administration of ASOs is desirable but highly challenging owing to the strong barrier imposed by the stratum corneum, which only permits the penetration of small molecules under 500 Da. For ASOs to exert their antisense effect, they must traverse the negatively charged cell membrane and reach the cytoplasm. In this study, we used the solid-in-oil (S/O) dispersion technology to facilitate the skin permeation of ASOs by coating the drug with a hydrophobic surfactant molecule, specifically lipid-based ionic liquid (IL) surfactants with high biocompatibility and transdermal penetration-enhancing properties. To induce the antisense effect, it was important to achieve simultaneous transdermal delivery and intracellular entrapment of ASOs. In vitro investigations indicated that the newly prepared IL-S/O enhanced the transdermal penetration and intracellular delivery of ASOs, thus inhibiting mRNA translation of the target TGF-β. In addition, in vivo investigations of tumor-bearing mice suggested that the anti-tumor effect of the IL-S/O was similar to that of injection. This study demonstrates the potential of non-invasive transdermal delivery carriers based on biocompatible ILs, which can be applied to a variety of nucleic acid drugs.
Keywords: antisense oligonucleotide; antitumor effect; cellular uptake; ionic liquid; nucleic acid drug; skin penetration; transdermal delivery.