A randomized, double-blind study comparing two commercially available botulinum toxin type A injections found abobotulinumtoxinA to be more effective than onabotulinumtoxinA for treating crow's feet.
The study, published online in the Archives of Facial Plastic Surgery (doi:10.1001/archfacial.2011.37), compared the effectiveness of abobotulinumtoxinA, marketed as Dysport, with onabotulinumtoxinA, marketed as Botox, in 90 patients with lateral orbital rhytids.
Investigator and patient assessments of Merz scale scores (a visual tool used to grade wrinkles on a severity scale of 0 to 4) before and at several points after treatment were collected; the primary endpoint was investigator assessment of maximal contraction 30 days post treatment. However, patients also were asked to assess results using the same scale.
AbobotulinumtoxinA was reported by both patients and investigators to be significantly more effective in reducing lines during maximum facial contraction.
Dr. Corey S. Maas of the department of otolaryngology–head and neck surgery at the University of California, San Francisco, who is in private practice, and his colleagues enrolled 90 patients between 31 and 78 years old (mean age 54.5 years) without previous surgery or facial injections for at least 6 months; 13 were men.
All were injected with 10 U of onabotulinumtoxinA on one side of the face and 30 U of abobotulinumtoxinA on the other, according to a 1:3 ratio employed in earlier studies and judged by the principal investigator to be the best comparative dose. The study investigators were blinded as to which side of the face received which treatment, as were patients. Treatments were prepared by a nonblinded nurse.
At baseline, investigators assessed patients as having mean Merz scale scores of 3.68 on the onabotulinumtoxinA-treated sides of their faces at maximal contraction; after treatment, this became 2.33. With abobotulinumtoxinA, investigators assessed patients as having a mean score of 3.64 at baseline and 2.60 after treatment, offering a statistically significant advantage to abobotulinumtoxinA.
Patients, using the same scale, assessed more improvement on the abobotulinumtoxinA side than on the onabotulinumtoxinA side at maximal contraction and favored results from the abobotulinumtoxinA sides 67% of the time.
No statistically significant difference was seen between the two treatments when the lateral orbital rhytids were at rest.
The study was the first to evaluate both products simultaneously in a patient; crow's feet were designated as the candidate wrinkles because of the minimal likelihood of the products diffusing from one side of the face to the other, the investigators wrote.
The investigators offered no explanation for why abobotulinumtoxinA appeared to work better, but wrote in their analysis that because the main pharmacologic difference between the two medications is the hemagglutinin and non-hemagglutinin surrounding each protein, "one may theorize that these differences in efficacy can be ascribed to the hemagglutinin and non-hemagglutinin binding."
Dr. Maas disclosed that he is a consultant for and owns stock in both Medicis Aesthetics (makers of abobotulinumtoxinA) and Allergan (makers of onabotulinumtoxinA). Medicis Aesthetics funded the study.