It appears most patients say they have better results from abobotulinumtoxinA when they contract their facial muscles, than with onabotulinumtoxinA - when muscles were at rest there was no statistical difference, researchers from The Maas Clinic, San Francisco, and the University of California, reported in Archives of Facial Plastic Surgery.
Botulinum toxin is a chemical that affects nerve impulses - it is a neuromodulator. It has medical and cosmetic uses, the authors explained as background information.
The FDA (Food and Drug Administration) approved botulinum toxin type A for two muscular conditions that impact on the appearance of the eyes.
OnabotulinumtoxinA was approved in 2002 for treatment for wrinkles between the eyebrows.
AbobotulinumtoxinA was approved in 2009, also for wrinkles between the eyes.
Kartik D. Nettar, M.D. and team set out to compare these two types of botulinum toxins, head to head.
The authors wrote:
"Such an assessment could characterize and contrast their efficacy in clinical performance in the treatment of hyperfunctional lines and muscular relaxation."
The team carried out a randomized, double-blind split-face study. One agent was used on the left side of the face, the other on the right.
The researchers wrote:
"By using a split-face (internally controlled) paradigm, this would provide direct comparison of each product in the same patient."
The study involved 90 patients. They received onabotulinumtoxinA and abobotulinumtoxinA on either side of their faces for the treatment of crow's feet (lateral orbital rhytids). A five-point scale was used by the researchers to assess each patient's appearance. Patient feedback data were also gathered.
The investigators found that abobotulinumtoxinA scored significantly higher when patients contracted the muscles as much as possible. The difference was clear both from the researchers' assessment and patient feedback. Over 65% of the participants said they preferred the results on the side of their face that received abobotulinumtoxinA.
When facial muscles were at rest no statistical difference between the two agents was found, the authors added.
"Ongoing studies will determine whether the demonstrated patient preference and early advantage in clinical outcomes is persistent. as both the efficacy in line effacement and duration of effect are both important factors in patient and physician decision-making as it related to the use of neuromodulators."
Arch Facial Plast Surg 2011;doi:10.1001/archfacial/2011.37.
Written by Christian Nordqvist