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Neosaxitoxin for Prolonged Local Anesthesia | Overview


Neosaxitoxin (NeoSTX) is a site-1 sodium channel blocker that produces local anesthesia. Under an FDA-approved phase 1 Investigational New Drug Trial, we evaluated safety and efficacy of NeoSTX, alone, and in combination bupivacaine, and with and without epinephrine.

What did the study involve?

84 male volunteers received two subcutaneous injections.  The control injection was bupivacaine, a local anesthetic used in clinical practice to cause numbness that lasts for 2 to 8 hours. The treatment injection was one of four drug combinations:

  1. Neosaxitoxin + Saline (NeoSTX-Saline)
  2. Neosaxitoxin + Bupivacaine (NeoSTX-Bup)
  3. Neosaxitoxin + Bupivacaine + Epinephrine (NeoSTX-Bup-Epi)
  4. Saline

We collected information on safety and adverse events e.g. perioral numbness and tingling over a 24 hour period.  We also performed skin sensation testing over a 24-hour period, and daily for two weeks.

  • Safety and adverse events measures included perioral numbness and tingling
  • Skin sensation testing (QST) involved measuring responses to touch and temperature. We wanted to look at duration of local anesthesia with each treatment

Who was eligible for this study?

  • Males only
  • 18-35 years old
  • No major health problems
  • No known allergies to local anesthetics
  • Not regularly taking pain controlling medications
  • Collaborating Research Groups

What did the study show?

  • NeoSTX combinations have a well-tolerated side effect profile and appear promising for prolonged local anesthesia.
  • Mean peak plasma concentration for the NeoSTX-Bupivacaine-Epinephrine group occurred much later and was at least 2-fold lower than for the NeoSTX-Bupivacaine and NeoSTX-Saline groups.

NeoSTX-Bupivacaine and NeoSTX-Bupivacaine-Epinephrine combinations showed reliable and prolonged cutaneous anesthesia, as assessed by QST.

This study involved a collaboration across BCH departments with researchers and clinicians in the Department of Anesthesiology, Perioperative & Pain Medicine, Department of Laboratory Medicine, and Department of Cardiology.
Our trial is registered on Safety Study of Long-Acting Local Anesthetic

Related Publications

Lobo K, Donado C, Cornelissen L, Kim J, Ortiz R, Peake RWA, Kellogg M, Alexander ME, Zurakowski D, Kurgansky KE, Peyton J, Bilge A, Boretsky K, McCann ME, Berde CB, Cravero J. A Phase 1 Dose Escalation, Double-Blind, Block Randomized Controlled Trial of Safety and Efficacy of Neosaxitoxin Alone and in Combination with 0.2% Bupivacaine, with and without Epinephrine, for Cutaneous Anesthesia. Anesthesiology 123(4):873-85.