A new study offers insight on how injections of onabotulinum toxin A may affect skin elasticity and pliability.
The researchers — James P. Bonaparte, M.D., of the Department of Otolaryngology-Head and Neck Surgery, University of Ottawa, and David Ellis, M.D., of the Division of Facial Plastic Surgery at the University of Toronto — undertook a prospective cohort study on the mechanism of action of botulinum type A on certain skin properties. “Understanding the natural course that onabotulinum toxin A has on the elasticity of skin may help physicians understand why there appears to be a progressive reduction in wrinkle levels with repeated treatments,” they write.
To determine whether onabotulinum toxin A increases skin pliability and elasticity with a corresponding decrease in the contribution of the viscoelastic component of skin resistance, Drs. Bonaparte and Ellis enrolled 48 onabotulinum toxin A-naïve women, with a mean age of 55 years, from October 1, 2012, through June 31, 2013. The participants, 43 of whom completed the study, had a minimum of mild wrinkle levels at the glabella and lateral orbit. Glabellas, supraorbits and lateral orbits were treated with onabotulinum toxin A and assessed at baseline, two weeks, two months, three months and four months post-injection.
For all three areas — the supraorbit, the glabella and the lateral orbit — there was a significant effect of time on pliability, elastic recoil and the ratio of viscoelastic to elastic distension (Uv/Ue ratio).
“This study provides further evidence that there is an alteration in biomechanical properties of the skin after injection with onabotulinum toxin A,” the authors write. “This effect appears to last up to four months in the glabella and up to three months at other sites. The decrease in the Uv/Ue ratio suggests onabotulinum toxin A injection does not result in an increase in tissue edema suggestive of an inflammatory reaction within the skin. However, it remains unclear whether this is due to an intrinsic property of the medication or another, unrecognized mechanism.”