Injectable thermosensitive lipo-hydrogels loaded with ropivacaine for prolonging local anesthesia.
Int J Pharm 2022;
611:121291. [PMID:
34780929 DOI:
10.1016/j.ijpharm.2021.121291]
[Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 10/26/2021] [Accepted: 11/08/2021] [Indexed: 02/05/2023]
Abstract
Reducing post-surgical pain can promote recovery of mobility, improve patient satisfaction, and reduce the risk of chronic pain syndrome. When managing post-surgical pain, single-injection local anesthesia is more convenient and involves lower risk to the patient than multi-injection regimes, but the effects are not long-lasting. Here we developed a system that can prolong local anesthesia after a single injection. In this system, ropivacaine (Ro) is encapsulated into liposomes, which are then loaded into Poloxamer 407-based thermosensitive hydrogels. The Ro-loaded liposome-in-gel system (Ro-Lip-Gel) is in a sol state before injection, and immediately after subcutaneous injection, it forms a gel in situ. We show through in vitro release and in vivo pharmacokinetics studies that this gel acts as a drug release depot. In rats, the initial burst release of Ro was smaller from Ro-Lip-Gel than from Ro solution or Ro-Gel, and Ro-Lip-Gel caused nerve blockade lasting four times longer than Ro solution. Ro-Lip-Gel degraded in vivo and showed good biocompatibility. Our results suggest that a liposome-in-gel system can show small initial burst release, long-term nerve blockade and good biocompatibility in vitro and in vivo. Therefore, such a system may be useful for sustained local anesthesia without systemic toxicity.
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