Comparison of Two Botulinum Toxin Type A Preparations for Treating Crow's Feet: A Split-Face, Double-Blind, Proof-of-Concept Study


Address correspondence and reprint requests to: Welf Prager, MD, Dermatologikum Hamburg, Stephansplatz 5, 20354 Hamburg, Germany, or e-mail:


BACKGROUND This is the first double-blind, randomized, proof-of-concept study to compare the clinical effectiveness of botulinum toxin type A (BoNTA) free of complexing proteins with a BoNTA complex (BTXCo) in the treatment of crow's feet.

PATIENTS AND METHOD Twelve U of each product were compared in an intra-individual study in 21 participants with a facial wrinkle scale (FWS) score of 2 to 3. Evaluations were done for up to 4 months. Subjects with an improvement of at least 1 point on the FWS were considered responders.

RESULTS One month after treatment, the percentage of responders was slightly higher for the BoNTA side (95%) than the BTXCo side (90%). After 4 months, both sides still showed good efficacy, with an 84% response rate and greater than 30% FWS reduction (no statistically significant difference between the products). After 1 month, FWS score at rest was approximately 66% lower for BoNTA, versus 63% lower for BTXCo. After 4 months, FWS reduction was approximately 50%.

CONCLUSION Both botulinum toxin A products displayed high efficacy and good tolerability at a dose ratio of 1:1, with no statistically significant differences between them. The high response rates observed after 4 months suggest a good effectiveness beyond this observation period.

This study was funded by an unrestricted educational fund from Merz, which also supplied the study medication.