Epidural anesthesia is a vital tool for obstetrical practice. Currently-available local anesthetics carry the concomitant effect of motor blockade. Past efforts toward diminishing this effect have included the addition of narcotic agents and close titration of local anesthetic dosing, but these approaches have not meaningfully achieved this goal. Here, we present the profile of a novel experimental agent (Agent A) which may provide true motor-sparing regional anesthesia. Agent A is an FDA-approved agent which we propose to re-purpose as a local anesthetic.
In vivo electrophysiological recordings and behavioral assessments were made in adult rats to assess sensory and motor conduction in peripheral nerves treated with Agent A. In vitro patch clamp recordings were made of isolated sensory neurons to examine properties of Agent A.
Agent A produced a reversible “sensory-preferential” block (sensory 100%; motor 60–70%) with more rapid motor recovery. Agent A acted directly on neurons to produce the block and was effective in both naïve and sensory-pathology conditions. Agent A is structurally different from existing local anesthetics and is FDA-approved for other unrelated purposes. The local anesthetic effect is likely not through its known receptor. Its history of clinical deployment and structural dissimilarity to existing agents suggests it may alleviate toxicity issues which limit current LA agents.
Agent A displays significant sparing of motor function while providing full sensory block. We encourage interaction and feedback regarding Agent A and the possibility that it may represent a clinically-feasible means of providing motor-sparing regional anesthesia for labor and delivery.
University of Louisville Department of Obstetrics, Gynecology, and Women's Health, Louisville, KY
Financial Disclosure: The authors did not report any potential conflicts of interest.