Respective Potencies of Botox® and Dysport® in a Human Skin Model : A Randomized, Double-blind Study

Mouse units used to quantify the activity of botulinum A toxin preparations are not equivalent and issues concerning efficacy and safety remain with regard to their respective potencies and diffusion qualities in human tissue. We compared the effects of Botox® (BOT) and Dysport® (DYS) in different doses and dilutions in a human skin model. Eighteen (8 women, 10 men) healthy volunteers, aged 28.4 years ± 5.7 years were injected intradermally with pure saline, BOT and DYS at 16 points in the abdomen in random order and in a double-blind condition, using two conversion ratios (1:3 and 1:4) and three different dilution schemes. For an objective outcome, the Ninhydrin sweat test was used to compare the anhidrotic areas. Both preparations showed a linear dose and dilution relationship with similar variances of responses for anhidrosis and hypohidrosis, indicating the same reliability of response. The dose equivalence conversion ratios (BOT: DYS) were 1:1.3 for anhidrosis and 1:1.6 for hypohidrosis (1:1.1-1.5 and 1:1.4-1.8 95% confidence intervals). The diffusion characteristics of both products were similar. A dose equivalence factor of more than 1:2 (BOT:DYS) is not supported by these objective and reproducible data. © 2008 Movement Disorder Society