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A Quantitative Analysis of Different Botulinum Toxin Formulations: A Randomized Double Blind Prospective Clinical Trial of Comparative Dynamic Strain Reduction
Catherine S Chang MD, Anthony J. Wilson, MD, Brian Chang, BS, Bianca C. Chin, MD, Anthony J. Taglinenti, MD, Nancy Folsom, RN, Ivona Percec, MD, PhD
University of Pennsylvania, Philadelphia, PA, USA.
A Quantitative Analysis of Different Botulinum Toxin Formulations: A Randomized Double Blind Prospective Clinical Trial of Comparative Dynamic Strain Reduction.
Purpose: FDA approved formulations of botulinum toxin include (onabotulinumtoxinA) Botox®, (abobotulinumtoxinA) Dysport®, and (incobotulinumtoxinA) Xeomin®. Prior comparative studies have relied upon static photographic wrinkle scales to determine toxin efficacy, without measuring true quantitative dynamic outcomes. Here our group uses Digital Image Correlation (DIC) to precisely compare dynamic strain reduction between available neurotoxins at 4 and 14 days post-treatment.
Methods: Following institutional IRB approval, 73 female patients between the ages of 18-75 and Fitzpatrick skin types I - VI were recruited. Patients with any prior neuromodulation or facial surgery were excluded. Following baseline imaging of dynamic glabellar furrow, patients were randomized to injection with 20 units of onabotulinumtoxinA, 60 units of abobotulinumtoxinA, or 20 units of incobotulinumtoxinA into the glabella by a single trained, blinded injector. Dosing and injection sites did not vary between subjects. Reimaging was conducted at 4 and 14 days following injection. Change in average dynamic strain of the glabella alone was calculated and compared between groups at all time points via a student’s t-test.
Results: A total of 73 patients were recruited and randomized. 25 patients received abobotulinumtoxinA, 25 received incobotulinumtoxinA and 23 were injected with onabotulinumtoxinA. At 4 days following injection all groups had a significant reduction in glabellar strain. Patients receiving incobotulinumtoxinA had a 17.90% reduction compared to 38.86% receiving abobotulinumtoxinA (p = 0.09) and 42.10% receiving onabotulinumtoxinA (p < 0.05). 14 days following injection, those patients receiving incobotulinumtoxinA had a 51.44% reduction in compression compared to a 70.17% reduction in those receiving abobotulinumtoxinA (p < 0.05) and 71.91% reduction in those receiving onabotulinumtoxinA (p < 0.05). At time point 4 days post injection incobotulinumtoxinA was 25.36% its maximal efficacy compared to 54.21% for abobotulinumtoxinA (p = 0.18) and 58.98% for onabotulinumtoxinA (p= 0.10). There was no correlation between patient age, Glogau or Fitzpatrick scales and strain reduction.
Conclusion: Digital image correlation (DIC) permits precise and quantitative measurements of changes of dynamic facial rhytids. Using the DIC technology, we demonstrate that incobotulinumtoxinA, abobotulinumtoxinA and onabotulinumtoxinA all result in effective strain reduction. However, at current dosing guidelines, the three FDA-approved neuromodulators do not have equivalent efficacy at reducing strain in the glabella. OnabotulinumtoxinA (20 units) and abobotulinumtoxinA (60 units) result in significantly greater reduction in strain when compared incobotulinumtoxinA (20 units). Furthermore, both abobotulinumtoxinA onabotulinumtoxinA act more rapidly than incobotulinumtoxinA, though this difference was not statistically significant. Our quantitative findings validate prior anecdotal observations and confirm clinical differences between neurotoxins currently available in the US. Importantly, these data further provide an evidence-based means for neurotoxin selection in facial neuromodulation and accordingly, optimization of patient outcomes.
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