Abstract
Background: OnabotulinumtoxinA and incobotulinumtoxinA are two botulinum
toxin A (BoNT‐A) formulations commonly used in esthetic medicine. They are dis‐
tinguished 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 im‐
munogenicity, especially in practices with high ambient temperatures.
Objectives: To assess the efficacy and longevity of unreconstituted incobotulinum‐
toxinA 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 con‐
ducted 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 facili‐
tate 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, in‐
dicating 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.

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