Layered dissolving microneedle containing a three-drug combination on the treatment of hypertrophic scar

Hypertrophic scars (HS), mainly caused by burns, trauma, and surgery, are associated with erythema, bumps, itching, and pain. The oral administration of Asiaticoside (AS) is a prevalent treatment for HS in clinical settings; however, its effectiveness is constrained due to its low bioavailability, necessitating high dosages for therapeutic impact. To mitigate this issue, we developed a layered dissolving microneedle (DMN) incorporating AS–ginsenoside Rb1–L–carnosine (A–G–C) at the tip for HS treatment. The tip layer of the DMNs comprised sodium carboxymethyl cellulose (CMC), while the base layer consisted of low-viscosity CMC to enhance mechanical strength. We examined its puncture performance, in vitro dissolution ability, and therapeutic effect on a rabbit ear model of HS. Histological analysis was performed by Hematoxylin and Eosin (H&E), Masson staining and Sirius red staining. The results demonstrated that the DMNs exhibited excellent puncture performance and dissolution rates. A-G-C DMNs were found to be effective in reducing scar thickness by measuring scar thickness changes. Histological analysis revealed that the A–G–C DMNs significantly reduced inflammation and collagen fiber deposition in scar tissue. Importantly, the therapeutic effect achieved with A–G–C DMNs was comparable to that of triamcinolone acetonide injection. These findings highlight the potential of DMNs loaded with A–G–C as a promising treatment modality for HS, offering improved bioavailability and therapeutic outcomes.