Exploration of Ultrasound-Enhanced Transdermal Delivery Efficiency and Anti-Inflammatory Effect of Rutin

<b>Background</b>: Rutin is a natural flavonoid extracted primarily from plants with anti-inflammatory and antioxidant properties, and it is highly valuable in the cosmetics industry. However, the poor transdermal permeability of rutin limits its application via transdermal administration. Previous studies have predominantly focused on chemical methods for enhancing penetration. This study investigated the potential of ultrasound as a physical method by which to augment the transdermal absorption and anti-inflammatory effects of rutin. <b>Method</b>: Through in vitro diffusion experiments, we analyzed the effects of the ultrasonic frequency and intensity on percutaneous absorption. The optimal ultrasound parameters were determined based on the intradermal retention rate, which is defined as the proportion of intradermal retention to the total penetration. Parameters with higher retention rates were considered optimal. To validate the anti-inflammatory efficacy of rutin delivered using the ultrasound-assisted method, we employed a tape-stripping technique to induce inflammation in BALB/c nude mice. Eight mice were assigned to each treatment group: (A) self-repair (control group), (B) regular rutin treatment, and (C) ultrasound-assisted treatment. <b>Results</b>: The research findings indicate that ultrasound frequency and intensity of 1 MHz and 0.2 W/cm², as well as 3 MHz and 0.2 W/cm², result in the maximum proportion of rutin intradermal retention, exhibiting values 1.8 times (using porcine skin) and 2.63 times (using nude mouse skin) higher than those achieved without ultrasound, respectively. Group C showed the shortest recovery time and displayed complete skin barrier function restoration by the fourth day (p<0.05), whereas group A exhibited the slowest recovery. <b>Conclusions</b>: This study offers an innovative approach for the transdermal delivery of rutin to facilitate skin barrier function repair.