Lidocaine/multivalent ion complex as a potential strategy for prolonged local anesthesia.

Local anesthetics are adopted in clinical practice to manage the perioperative and/or postoperative pain. However, their relatively short duration of action limit their ability to meet clinical needs. Herein, we prepared a lidocaine/multivalent ion complex (icLD) using aqueous solutions containing positively charged LD and a multivalent counter-ion as a system for producing prolonged anesthesia. The results of the in vitro and in vivo experiments indicated that the icLD facilitates prolonged LD release even without adjuvants and thus provides nerve blockade for a long duration of action (∼14h) without further increase in neurotoxicity than the LD itself. These findings suggested that the icLD could be a practical strategy for effectively controlling perioperative and/or postoperative pain in clinical practice.