Pharmacokinetics of Single-Dose Liposomal Bupivacaine in Surgeon Performed Intercostal Nerve Blocks

Post-surgery pain management is critical for ensuring timely patient recovery and minimizing complications. Part of the multimodal approach to managing severe acute pain in the days following surgeries is the use of nerve blocks. The relatively short-lived effect of commonly used local anesthetics recently prompted the development and subsequent approval of a liposomal formulation of bupivacaine (Exparel; Pacira Pharmaceuticals, Parsippany, New Jersey). It has demonstrated favorable pharmacokinetics compared to bupivacaine HCl(hydrochloride), with a slower release into blood stream of up to 96 hours after administration, following a single dose wound infiltration at the end of various surgeries. Studies using other modes of administration reported similar results.

Thoracic surgeries pose an exceptional challenge as they are one of the most painful surgeries and poor pain-management contributes to reduced quality of life and severely delayed recovery. The anesthesiology protocol within the Enhanced Recovery After Surgery (ERAS) program at medical centers across the world aim to increase patient comfort after surgery while reducing complications and use of opioids. As a common part of this protocol, intercostal nerve blocks with liposomal bupivacaine are regularly utilized for reduction of post-thoracotomy pain and studies show that it may be just as or more effective than bupivacaine HCl for treatment of pain, decreasing hospital stays and reducing the incidence of complications.

Despite its frequent use in the surgical room for nerve blocks, the pharmacokinetics of a single dose injection of liposomal bupivacaine at the intercostal nerves has never been investigated. The aim of this study is to assess the pharmacokinetics of liposomal bupivacaine injected at the intercostal nerves. The results of this small-scale study will aid in the development of larger such studies in the future, and may aid in the standardization of post-thoracotomy pain management. Specifically, the information gleaned from this study will allow for the optimal use of additional local anesthetics, particularly those administered intravenously, for the purpose of obtaining maximal pain relief while minimizing the occurrence of local anesthetic toxicity.