Noninvasive transdermal drug delivery (TDD) can provide sustained systemic therapy while avoiding first-pass metabolism and oral-administration limitations. However, the stratum corneum (SC) is a major barrier to passive TDD of most small-molecule drugs. This study evaluated an approach that combines nanoscale carriers and hydrogel formulation to achieve passive systemic delivery of rosiglitazone (RGT), an antidiabetic agent, for management of Type 2 diabetes mellitus (T2DM).
The authors designed ultrasmall polymeric micelles (PMs) intended to interact with skin lipids and traverse the SC without invasive enhancement methods. PMs were embedded within poly(vinyl alcohol) hydrogels to create a stable topical dosage form suitable for prolonged contact with skin.
To control interactions with the SC and preserve colloidal stability, the investigators synthesized amphiphilic brush copolymers with different hydrophobic core moieties. The hydrophobic cores evaluated included linear alkane chains of varying length, benzene, and borneol. These structural variations were used to tune micelle hydrophobicity and the micelle–lipid interface, with the goal of optimizing transdermal permeation while maintaining carrier stability.
PMs were loaded with rosiglitazone and then incorporated into a poly(vinyl alcohol) hydrogel matrix to produce a topical hydrogel capable of sustained drug release and prolonged skin contact.
Ex vivo studies using murine skin were performed to quantify permeation of RGT from PM variants. Two PM formulations showed notable permeation at 24 hours: the variant with a C10 alkane core and the variant with a benzene core. Cumulative permeation at 24 h was reported as 10.56% for the C10 alkane core PMs and 19.84% for the benzene core PMs. These results indicate that hydrophobic-core chemistry influenced transdermal flux and cumulative delivery over the study period.
The authors described the observed transport across the skin as occurring via dual pathways, involving both paracellular and intracellular routes through the epidermal layers.
Mechanistic interpretation in the article attributes PM-enabled permeation to two complementary phenomena. First, interaction of the PMs with stratum corneum lipids produced lipid fluidization, a reversible perturbation of the ordered lipid matrix that can increase permeability to small molecules and nanoscale carriers. Second, PMs appear to engage cellular translocation processes described as transcytosis, enabling intracellular trafficking across viable epidermal layers and into deeper skin compartments. Together, lipid fluidization and transcytosis are presented as the basis for noninvasive systemic uptake.
When administered in vivo as PM-loaded hydrogels, the formulation delivered rosiglitazone systemically, producing steady plasma accumulation of the drug. The paper reports that topical application of the PM hydrogels achieved measurable, sustained plasma levels consistent with transdermal absorption and systemic exposure.
The therapeutic potential of transdermal RGT delivered by the PM hydrogels was evaluated in an animal model of T2DM. Over a 12-day treatment period, transdermal RGT reduced blood glucose levels by 30%, demonstrating pharmacodynamic efficacy of the noninvasive delivery approach in this disease model.
Throughout the experimental treatment period, the authors report that there were no observable signs of skin irritation or organ toxicity associated with PM hydrogel application. Safety assessments in the study indicated tolerability of the formulation under the reported conditions.
This work demonstrates that carefully designed ultrasmall polymeric micelles embedded in poly(vinyl alcohol) hydrogels can enable passive, noninvasive transdermal delivery of rosiglitazone by combining lipid fluidization of the stratum corneum with transcytosis-mediated transport. Ex vivo data identified specific hydrophobic-core chemistries (C10 alkane and benzene) that produced measurable permeation, and in vivo studies showed steady plasma accumulation and a 30% reduction in blood glucose over 12 days in a T2DM model without observed skin or organ toxicity.
The authors position this nanoplatform as a potential alternative to oral administration for sustained glycemic control. Details such as exact formulation parameters, full pharmacokinetic profiles, long-term safety beyond the reported period, and translational considerations were not further reported in the abstract and would require consultation of the full article for comprehensive evaluation.