Comparative Pharmacodynamics Study of 3 Different Botulinum Toxin Type A Preparations in Mice.

[BACKGROUND] A new complexing protein-free botulinum toxin Type A (CBoNT) with the same mechanism of action as the botulinum toxin complex onabotulinumtoxinA (OBoNT) and complexing protein-free incobotulinumtoxinA (IBoNT) was recently developed.

[OBJECTIVE] To compare the local paresis and chemodenervation efficacy of 3 different botulinum toxin Type A preparations in mice.

[MATERIALS AND METHODS] Efficacy and duration of action of CBoNT, OBoNT, and IBoNT after a single intramuscular injection to the right gastrocnemius was evaluated by digit abduction score (DAS) and compound muscle action potential (CMAP) assays.

[RESULTS] Mouse DAS and CMAP responses were comparable between CBoNT and OBoNT, indicating similar paresis and chemodenervation efficacy, as well as duration of action. Both botulinum toxins showed significantly higher efficacy and longer duration of action than IBoNT. Similarly, mean DAS potency of CBoNT (ED50: 3.85 ± 0.34 U/kg) and OBoNT (ED50: 4.13 ± 0.07 U/kg) were significantly higher compared with IBoNT (ED50: 6.70 ± 0.83 U/kg).

[CONCLUSION] CBoNT displays the same efficacy as OBoNT as shown by their comparable chemodenervation and local paretic effects, and demonstrates superior efficacy and duration of action compared with IBoNT. Likewise, CBoNT has comparable DAS potency to OBoNT and is superior to IBoNT.