Novel Local Anesthetics in Clinical Practice: Pharmacologic Considerations and Potential Roles for the Future

Abstract

: The treatment of pain, both acute and chronic, has been a focus of medicine for generations. Physicians have tried to develop novel ways to effectively manage pain in surgical and post-surgical settings. One intervention demonstrating efficacy is nerve blocks. Single-injection peripheral nerve blocks (PNBs) are usually preferred over continuous PNBs, since they are not associated with longer lengths of stay. The challenge of single injection PNBs is their length of duration, which at present is a major limitation. Novel preparations of local anesthetics have also been studied, and these new preparations could allow for extended duration of action of anesthetics. An emerging preparation of bupivacaine, exparel, uses a multivesicular liposomal delivery system which releases medication in a steady, controlled manner. Another extended-release local anesthetic, HTX-011, consists of a combination of bupivacaine and low-dose meloxicam. Tetrodotoxin, a naturally occurring reversible site 1 sodium channel toxin derived from pufferfish and shellfish, has shown the potential to block conduction of isolated nerves. Neosaxitoxin is a more potent reversible site 1 sodium channel toxin also found in shellfish that can also block nerve conduction. These novel formulations show great promise in terms of the ability to prolong the duration of single injection PNBs. This field is still currently in development, and more researchers will need to be done to ensure the efficacy and safety of these novel formulations. These formulations could be the future of pain management if ongoing research continues to prove positive effects and low side effect profiles.

Comparative Randomized Study between Pulsed Radiofrequency and Suprascapular Nerve Block for the Treatment of Chronic Shoulder Pain

“…4 In addition, bupivacaine is slowly released over several days following injection. 18 Although the local anesthetic lasts for a few hours, it can promote a reduction in sensitization, with a lasting effect. The authors of one study observed a gain in the range of motion over 24 weeks.…”

“…Pain relief after the block was also maintained for 3 months in a meta-analysis 4 . In addition, bupivacaine is slowly released over several days following injection 18 . Although the local anesthetic lasts for a few hours, it can promote a reduction in sensitization, with a lasting effect.…”

Optimizing pediatric periprocedural pain management part II—Adjunct therapies to support the use of infiltrative anesthetics

“…Over the past decade, there has been increasing research into novel drug delivery systems, with a goal of increasing the duration of local anesthetics. For example, the development of liposomal bupivacaine may lengthen nerve block durations, the clinical significance of which is still under investigation 87 . While most of this research is currently focused on topics out of the scope of this review, such as nerve blocks and postoperative pain control, investigations into polymer nanocarriers will likely impact numerous drug classes and guide future pediatric research in this arena.…”

Measures to prolong duration of sensory block after regional anaesthesia

“…Other novel experimental preparations as HTX-011 [13][14][15], a combination of bupivacaine and meloxicam, or naturally occurring reversible sodium channel blockers as tetrodotoxin [16,17] or neosaxitoxin [18], have been studied. Even though these novel substances have shown success in theoretically prolonging the duration of action of local anaesthetics, future research will be needed to prove their efficacy and safety in clinical studies [19,20].…”