Two different types of botulinum toxins: Is there a difference in efficacy and longevity?

[BACKGROUND] OnabotulinumtoxinA and incobotulinumtoxinA are two botulinum toxin A (BoNT-A) formulations commonly used in esthetic medicine. They are distinguished by whether complexing proteins are included with the active neurotoxin. While OnabotulinumtoxinA has complexing proteins, incobotulinumtoxinA does not; yet, it is unclear whether these differences affect their efficacy, longevity, and immunogenicity, especially in practices with high ambient temperatures.

[OBJECTIVES] To assess the efficacy and longevity of unreconstituted incobotulinumtoxinA with unreconstituted OnabotulinumtoxinA when stored and transported in a cold box to areas with high external ambient temperatures and to understand the implications of storing and transporting botulinum toxin to tropical areas with high ambient temperatures.

[METHODS] A prospective, randomized, and evaluator-blinded split-face trial was conducted in 30 patients with symmetrical, moderate-to-severe forehead lines. Following routine transportation and storage in thermocol cold boxes, OnabotulinumtoxinA or incobotulinumtoxinA was injected into corresponding sides of the frontalis to facilitate analysis within the same patient. Using a 4-point facial wrinkling grading scale and a clinical improvement scale, patients' outcomes were assessed over 24 weeks.

[RESULTS] Forehead lines reappeared in OnabotulinumtoxinA-treated patients after 8.3 weeks, compared to 10.1 weeks in incobotulinumtoxinA-treated patients. While side-vs-side improvements in forehead lines were observed for both toxins, after 8 weeks, improvements from were diminished relative to incobotulinumtoxinA, indicating that incobotulinumtoxinA was more effective at prolonged wrinkle relief.

[CONCLUSIONS] These results suggest that incobotulinumtoxinA is more stable at higher ambient temperatures, thus contributing to its better efficacy and longevity. IncobotulinumtoxinA is therefore more appropriate for practices in tropical climates.