Ketorolac tromethamine-loaded hydrogel-forming microneedles for pediatric pain relief.

Pain is particularly intolerable for children, and the analgesic regimen must be carefully managed, as systemic delivery may lead to serious side effects to growth and development of children. Therefore, the research and development of pain-relieving formulations and administration routes specifically tailored for children are both meaningful and essential to enhance treatment compliance. In this study, ketorolac tromethamine (KT)-loaded hydrogel-forming microneedle (MN) were designed, prepared, and evaluated using methacrylic anhydride -modified hyaluronic acid as the MN matrix. Conical, tetrapyramidal and candle-like tip geometries with distinct profiles were fabricated. The relationship between tip geometry and mechanical strength was systematically evaluated, revealing that the candle-like MN (KT-TMN) exhibits superior mechanical performance. Comprehensive characterization was conducted on the morphology, mechanical properties, insertion capability, safety profile, and drug release kinetics of the MN system. Results from the acetic acid-induced writhing test and hot plate test demonstrated that KT-TMN significantly prolonged pain latency and reduced writhing responses in mice, exhibiting an analgesic efficacy comparable to intravenous administration of KT. In vivo pharmacokinetic studies revealed that KT-TMN enabled stable and sustained drug release, highlighting its potential for transdermal delivery of KT as a pediatric analgesic agent.