A ropivacaine-eluting poly(lactide-co-caprolactone) wound dressing provided enhanced analgesia in partial-thickness porcine injuries

Background: Partial-thickness skin wounds are some of the most painful injuries due to large areas of exposed nerve endings. These injuries often require systemic opioid treatments to manage pain adequately. However, in 2021 alone, the CDC reported nearly 17,000 prescription opioid-related deaths in the USA, highlighting the ongoing need for non-opioid treatment strategies. In this manuscript, we developed a novel single-application ropivacaine-eluting primary wound dressing that could provide sustained ropivacaine delivery to partial-thickness wounds and assessed its in vivo feasibility for prolonged non-opioid analgesia. Methods: Sustained release of ropivacaine from a poly(lactide-co-e-caprolactone) matrix was first optimized in vitro using dissolution testing and a Box Behnken design of experiments. The optimized dressing was then tested against a clinical control silicone dressing in a porcine partial-thickness wound study to assess analgesic effect, pharmacokinetics, and wound healing. Results: The ropivacaine-eluting dressing showed a moderate analgesic effect in vivo, where normalized single pinprick scores significantly improved pain over the testing period (4-168h) (control vs treatment: 232±25% vs 145±16%, p<0.0003). Ropivacaine blood plasma levels peaked at 8 hours post-treatment, with a maximum concentration of 246 ± 74 ng/mL. No significant differences in wound healing were found when compared to control. Conclusion: The ropivacaine-loaded poly(lactide-co-e-caprolactone)-based wound dressing provided sustained delivery of ropivacaine to partial-thickness skin wounds and enhanced analgesic effect compared to a clinical standard control dressing.