Controlled-release hybrid hydrogels delivering synergistic N-acetyl cysteine, ibuprofen, and progesterone combinations for enhanced peripheral nerve regeneration.

Peripheral nerve injuries (PNI) remain a major clinical challenge, particularly for defects exceeding 3 cm. Autografts are the current gold standard for small gaps, but their use is limited by donor site morbidity, infection risk, and poor outcomes in larger defects. Synthetic grafts and allografts have achieved only modest clinical success, underscoring the need for therapeutic systems that actively support regeneration. This study investigated three FDA-approved drugs - N-acetyl cysteine (NAC), ibuprofen (Ibu), and progesterone (Prog) - for their synergistic potential to enhance Schwann cell (SC) and PC-12 cell proliferation as a strategy for peripheral nerve repair. High-throughput screening using Alamar Blue assays assessed viability and proliferation at 24, 48, and 72 h across dual- and triple-drug combinations. The optimised formulation of 75 µM NAC, 16.25 µM Ibu, and 30 µM Prog significantly increased proliferation compared with untreated controls without inducing cytotoxicity. A validated high-performance liquid chromatography (HPLC) method was developed to quantify simultaneous release of all three drugs from polyethylene glycol dimethacrylate-dipentaerythritol hexa(3-mercaptopropionate) (PEGDMA-DiPETMP) hydrogels. Controlled, sequential release was achieved, with complete elution of NAC within 24 h, Ibu within 72 h, and Prog over 21 days. These timelines correspond to the early antioxidative, anti-inflammatory, and neurotrophic phases of peripheral nerve repair. Although proliferation assays were conducted using directly applied drug combinations, the established release behaviour provides a mechanistic rationale for future validation of hydrogel-mediated delivery. The synergistic combination of NAC, Ibu, and Prog delivered from PEGDMA-DiPETMP hybrid hydrogels provides a reproducible and temporally coordinated release platform that promotes cellular proliferation and supports peripheral nerve regeneration.