Preparation and In Vitro/In Vivo Characterization of Mixed-Micelles-Loaded Dissolving Microneedles for Sustained Release of Indomethacin

<b>Background/Objectives:</b> Indomethacin (IDM) is commonly used to treat chronic inflammatory diseases such as rheumatoid arthritis and osteoarthritis. However, long-term oral IDM treatment can harm the gastrointestinal tract. This study presents a design for encapsulating IDM within mixed micelles (MMs)-loaded dissolving microneedles (DMNs) to improve and sustain transdermal drug delivery. <b>Methods:</b> Indomethacin-loaded mixed micelles (IDM-MMs) were prepared from Soluplus^® and Poloxamer F127 by means of a thin-film hydration method. The MMs-loaded DMNs were fabricated using a two-step molding method and evaluated for storage stability, insertion ability, in vitro release, in vitro transdermal penetration, and in vivo PK/PD studies. <b>Results:</b> The obtained MMs were stable at 4 °C and 30 °C for 60 days. The in vitro IDM transdermal penetration was remarkably improved by the MMs-loaded DMNs compared to a commercial patch. A pharmacokinetic study demonstrated that the MMs-loaded DMNs had a relative bioavailability of 4.1 in comparison with the commercial patch. Furthermore, the MMs-loaded DMNs showed a significantly shorter lag time than the commercial patch, as well as a more stable plasma concentration than the DMNs without MMs. The therapeutic efficacy of the IDM DMNs was examined in Complete Freund's Adjuvant-induced arthritis mice. The IDM DMN treatment effectively reduced arthritis severity, resulting in decreased paw swelling, arthritis index, spleen hyperplasia, and serum IL-1β and TNF-α levels. <b>Conclusions:</b> Our findings demonstrated that the novel MMs-loaded DMNs were an effective strategy for sustained IDM release, providing an alternate route of anti-inflammatory drug delivery.