Strategy for osteoarthritis therapy: Improved the delivery of triptolide using liposome-loaded dissolving microneedle arrays

Osteoarthritis (OA) is a chronic disease that seriously impairs people's physical function and quality of life. Triptolide (TP), as a promising anti-inflammatory drug for the treatment of OA, has limited clinical application due to its severe systemic toxicity, poor solubility and rapid elimination in the body. To extend its application prospect for OA treatment. We have developed a liposome-loaded dissolving microneedle (DMN) system, which can effectively deliver poorly water-soluble TP and improve OA symptoms. To incorporate TP into DMNs, triptolide liposome (TP-Lipo) with entrapment efficiency of 90.25% was prepared by ethanol injection. Subsequently, TP-Lipo was concentrated by ultrafiltration tube and mixed with hyaluronic acid solution to prepare DMNs, TP-Lipo-loaded DMNs (TP-Lipo@DMNs) showed sufficient mechanical and insertion properties to penetrate about 200 μm of rat skin. The drug distribution in vivo showed that TP-Lipo@DMNs had a slow-release effect compared with intra-articular injection. In vivo pharmacodynamic research showed that TP-Lipo@DMNs significantly reduced knee joint swelling and the level of inflammatory cytokines (TNF-α, IL-1β, IL-6). Micro-CT and histological evaluation showed that TP-Lipo@DMNs effectively reduced cartilage destruction and alleviated OA symptoms. These results support that TP@Lipo@DMNs may be a promising option for OA treatment.