Long-term effect of ropivacaine nanoparticles for sciatic nerve block on postoperative pain in rats

Abstract

Purpose The analgesic effect of ropivacaine (Rop) for nerve block lasts only ~3–6 hours for single use. The aim of this study was to develop long-acting regional anesthetic Rop nanoparticles and investigate the effects of sciatic nerve block on postoperative pain in rats. Materials and methods Rop nanoparticles were developed using polyethylene glycol-co-polylactic acid (PELA). One hundred and twenty adult male Wistar rats were randomly divided into four groups (n=30, each): Con (control group; 0.9% saline, 200 µL), PELA (PELA group; 10 mg), Rop (Rop group; 0.5%, 200 µL), and Rop-PELA (Rop-PELA group; 10%, 10 mg). Another 12 rats were used for the detection of Rop concentration in plasma. The mechanical withdrawal threshold and thermal withdrawal latency were measured at 2 hours, 4 hours, 8 hours, 1 day, 2 days, 3 days, 5 days, and 7 days after incision. The expression of c-FOS was determined by immunohistochemistry at 2 hours, 8 hours, 48 hours, and 7 days. Nerve and organ toxicities were also evaluated at 7 days. Results The duration of Rop absorption in the plasma of the Rop-PELA group was longer (>8 hours) than that of the Rop group (4 hours). Mechanical withdrawal threshold and thermal withdrawal latency in the Rop-PELA group were higher than that in other groups (4 hours–3 days). c-FOS expression in the Rop-PELA group was lower than that in the control group at 2 hours, 8 hours, and 48 hours and lower than that in the Rop group at 8 hours and 48 hours after paw incision. Slight foreign body reactions were observed surrounding the sciatic nerve at 7 days. No obvious pathophysiological change was found in the major organs after Rop-PELA administration at 7 days. Conclusion Rop-PELA provides an effective analgesia for nerve block over 3 days after single administration, and the analgesic mechanism might be mediated by the regulation of spinal c-FOS expression. However, its potential long-term tissue toxicity needs to be further investigated.

Ultrasound-triggered on Demand Lidocaine Release Relieves Postoperative Pain

“…Studies speci cally designed to address this issue are required. Sustained-release local anesthetics have been reported to treat postoperative pain [5]. The liposomal bupivacaine injectable suspension (EXPAREL®; Pacira Pharmaceuticals, Inc., USA) has received FDA Approval for in ltration into a surgical site to provide postoperative analgesia in adults based on clinical trials in which subjects had undergone bunion reaction [29] and hemorrhoidectomy [30], demonstrating e cacy for 36 h and 72 h, respectively.…”

“…Studies have reported that 10-50% of patients undergoing surgery experience postoperative pain lasting more than 1 month, and 2-10% of these patients continue to experience moderate to severe chronic pain [3]. Although many new devices for postoperative pain have been developed, inadequate postoperative analgesia occurs because the anesthetic cannot meet the ondemand requirements [4][5][6]. Inadequate management of postoperative pain can lead to severe consequences, such as poor immediate postoperative effects, prolonged hospital stays, poor patient satisfaction, and increased burden on patients and health systems [1,7,8].…”

<p>Topical anesthetic analgesic therapy using the combination of ropivacaine and dexmedetomidine: hyaluronic acid modified long-acting nanostructured lipid carriers containing a skin penetration enhancer</p>

“…Studies with solid lipid nanoparticles, silver nanoparticles, and liposomes have been shown to increase the anesthesia duration of drugs formulations, when compared to their respective plain solutions 35–37. As a widely used local anesthesia in clinics, the efficacy of RVC was preferred because of its reduced toxicity 38. Thus, we imagined the treatment of pain with long-acting RVC is exciting.…”

Ultrasound-Triggered on Demand Lidocaine Release Relieves Postoperative Pain

“…Studies have reported that 10%–50% of patients undergoing surgery experience postoperative pain lasting more than 1 month, and 2%–10% of these patients continue to experience moderate to severe chronic pain ( Wang et al, 2020 ). Although many new devices for postoperative pain have been developed, inadequate postoperative analgesia occurs because the anesthetic cannot meet the on-demand requirements ( Tobe et al, 2010 ; Wang et al, 2016 ; Rwei et al, 2017 ; Chen et al, 2020 ). Inadequate management of postoperative pain can lead to severe consequences, such as poor immediate postoperative effects, prolonged hospital stays, poor patient satisfaction, and increased burden on patients and health systems ( Beaulieu, 2021 ; Joseph et al, 2021 ; Park et al, 2021 ).…”