Importance: Multiple botulinum toxin A formulations were approved by the US Food and Drug Administration for treating the glabellar rhytids. A comparative quantitative evaluation of their effects on the glabella has not been conducted.
Objective: To provide an objective quantitative assessment of the effect of 4 botulinum toxin A formulations on glabellar strain across using dynamic 3-dimensional photogrammetry.
Design, setting, and participants: This single-center, double-blind clinical trial, conducted at the University of Pennsylvania Division of Plastic Surgery clinic, randomized 143 female individuals aged 30 to 65 years into 4 arms receiving different botulinum toxin A formulations on day 0 and with follow-up at days 3, 30, 90, and 180. Dynamic 3-dimensional photogrammetry and surveys were collected from March 2022 to June 2023 and analyzed from July 2023 to April 2024.
Interventions: Participants were randomized 1:1:1:1 into 4 treatment arms: 1 dose of 20 units of onabotulinum toxin A (OBoNT/A); 1 dose of 60 units of abobotulinum toxin A (ABoNT/A); 1 dose of 20 units of prabotulinum toxin A (PBoNT/A); or 1 dose of 20 units of incobotulinum toxin A (IBoNT/A) into the glabellar region (GR).
Main outcomes and measures: The primary outcome was change in GR dynamic strain after injection over time. Secondary outcomes included changes in patient-reported satisfaction, the relationship between baseline strain severity and postinjection improvement in strain, and the effect on the strain of the untreated lateral canthal region.
Results: This study recruited 143 female individuals with a mean (SD) age of 43.5 (9.8) years. ABoNT/A and PBoNT/A had the fastest onset at day 3. PBoNT/A and IBoNT/A retained efficacy at day 180 compared with their baseline. Increasing baseline glabellar strain severity resulted in increased improvement with treatment. Lateral canthal region strain increased with decreasing GR strain. PBoNT/A was significantly more effective at day 180 than OBoNT/A. All arms experienced improvement in related FACE-Q module scores up to 90 days.
Conclusions and relevance: This randomized clinical trial found that ABoNT/A and PBoNT/A displayed the most rapid onset of effect. The peak effect is similar across all toxins. When measuring strain at approximately 6 months, some toxins remain significant relative to their own baseline or compared with other specific toxins.
Trial registration: ClinicalTrials.gov Identifier: NCT05167864.