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Related Experiment Video

Updated: Apr 3, 2026

A High-throughput-compatible FRET-based Platform for Identification and Characterization of Botulinum Neurotoxin Light Chain Modulators
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Clinical differences between A1 and A2 botulinum toxin subtypes.

Ryuji Kaji1

  • 1Department of Neurology, Institute of Health-Bioscience, Tokushima University, 2-50-1 Kuramoto-cho, Tokushima 770-8503, Japan.

Toxicon : Official Journal of the International Society on Toxinology
|September 23, 2015
PubMed
Summary

A new botulinum toxin A2NTX shows higher efficacy and less muscle spread than onabotulinumtoxinA for treating post-stroke spasticity. This subtype A2 preparation offers a promising alternative for improving patient function.

Keywords:
A2NTXHigher efficacy and safetyLess spreadLower limb spasticitySubtype A1Subtype A2 botulinum toxin

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Area of Science:

  • Neuroscience
  • Pharmacology
  • Biochemistry

Background:

  • Type A botulinum toxins are widely used clinically, primarily subtype A1.
  • Current treatments for post-stroke spasticity have limitations regarding efficacy and spread of effect.

Purpose of the Study:

  • To compare the efficacy and safety of a novel low-molecular weight subtype A2 botulinum toxin preparation (A2NTX) against onabotulinumtoxinA (subtype A1) for treating post-stroke spasticity.

Main Methods:

  • A double-blind, randomized controlled study (NCT01910363) involving 300 units of either A2NTX or onabotulinumtoxinA.
  • Efficacy was assessed by clinical evaluation and Functional Independence Measure (FIM) scores at 30 days post-injection.
  • Muscle spread was measured by hand grip strength on the unaffected side.

Main Results:

  • A2NTX demonstrated significantly higher efficacy compared to onabotulinumtoxinA at 30 days post-injection.
  • A2NTX showed significantly less spread of effect to the unaffected limb compared to onabotulinumtoxinA.
  • Functional Independence Measure (FIM) scores significantly improved with A2NTX, but not with onabotulinumtoxinA.

Conclusions:

  • The novel subtype A2 botulinum toxin (A2NTX) is a promising new treatment for post-stroke spasticity, offering superior efficacy and reduced muscle spread.
  • Further large-scale clinical trials are warranted to confirm these findings and support broader clinical adoption.