Integrated formulation and thermal modulation strategies for enhancing anti-inflammatory transdermal delivery of...

Transdermal patches are widely used for local anti-inflammatory therapy, but their delivery efficiency is often limited by the barrier function of the stratum corneum. This study aimed to develop an optimized dracorhodin transdermal patch and to evaluate temperature-controlled heating as a physical enhancement strategy using ketoprofen patches as a representative anti-inflammatory model. Dracorhodin ethanol extract was prepared by ethanol extraction and rotary evaporation, and a high-performance liquid chromatography method was established for quantitative analysis. Azone, isopropyl myristate, and acrylate pressure-sensitive adhesive were screened as key excipients, and dracorhodin patches were prepared using a coating method. The optimized patches were evaluated for appearance, content uniformity, adhesion, in vitro skin permeation, and anti-inflammatory activity using an egg white-induced rat paw swelling model. The optimized dracorhodin patch exhibited uniform morphology, satisfactory content uniformity, stable adhesion, and sustained skin permeation, achieving a cumulative permeation amount of 13-20 μg/cm² within 28 h. In vivo pharmacodynamic evaluation showed that the dracorhodin patch produced a swelling inhibition rate of 62.18% at 4 h, approaching that of the ketoprofen positive control. Furthermore, temperature-controlled heating significantly enhanced ketoprofen transdermal delivery, increasing permeation performance and improving intradermal diffusion and systemic exposure. Heating at 40 °C for 90 min achieved an optimal balance between enhancement efficiency and practical applicability. Overall, this study demonstrates that rational formulation optimization can effectively improve the performance of dracorhodin transdermal patches, while temperature-assisted enhancement provides a promising physical strategy for overcoming the limitations of conventional transdermal delivery. These findings provide a foundation for the future development of advanced anti-inflammatory patch systems integrating optimized formulations with controllable thermal regulation technologies.