Needle-free transdermal patches for insulin delivery in diabetes treatment

Abstract

Developing a non-invasive insulin delivery system is crucial for improving diabetes management and patient compliance. Transdermal drug delivery offers a promising alternative to direct injection. However, the strong barrier function of the stratum corneum and the limitations of solution-based formulations hinder the effective penetration of insulin into the skin. To enhance transdermal delivery of insulin, we developed a needle-free ionic liquid-in-oil (IL/O) patch by integrating an IL/O microemulsion with an acrylic pressure-sensitive adhesive. The patch formulation included choline oleate as the biocompatible surface-active IL, sorbitan monolaurate as the co-surfactant, choline propionate as the non-aqueous polar phase, isopropyl myristate as the oil phase, and DURO-TAK® 87-4098 as the adhesive matrix. The IL/O patch adhered stably to the skin and facilitated insulin transport via the intercellular route by increasing the fluidity of lipids in the stratum corneum. In vivo pharmacodynamics revealed that, compared with the subcutaneous injection (dosage of 10 IU/kg), the IL/O patch (dosage of 50 IU/kg) maintained stable blood glucose levels in diabetic mice for up to 72 h, indicating sustained insulin release. The patch demonstrated excellent biocompatibility and low toxicity, making it a promising non-invasive alternative for transdermal insulin delivery and a potential platform for peptide and protein-based therapeutics.