A Prospective, Neurophysiologic Comparative Study to Assess the Efficacy and Duration of Effect of IncobotulinumtoxinA and AbobotulinumtoxinA in the Treatment of Crow's Feet.

This randomized, rater-blind, split-face study compared the safety and efficacy of incobotulinumtoxinA and abobotulinumtoxinA for the treatment of crow's feet. Nine units of incobotulinumtoxinA were administered to the lateral periorbital region of one side of the face and 27 units of abobotulinumtoxinA to the other in healthy subjects (aged 35-55 years) with moderate-to-severe crow's feet at rest (2-3 points on the 5-point Merz Aesthetics Scale [MAS]). Investigators assessed efficacy using the MAS, while subjects assessed using a 9-point global assessment scale. Secondary objectives included electromyography to assess muscle activity before injection and at 2 weeks, 4 months, and 6 months afterwards. Twenty women were enrolled and 18 completed the study. At rest and maximum smile, at each time point, the mean wrinkle scores were significantly lower (P ≤ 0.05) than baseline for both treatments. No differences were noted between treatments. Responder (≥ 1-point improvement from baseline) rates for both products were 100% and 83% at 2 weeks and 4 months post-treatment, respectively. At 6 months post-treatment, responder rates were 67% and 61% for incobotulinumtoxinA and abobotulinumtoxinA, respectively. For both, the maximum changes in electromyography parameters were observed 2 weeks post-treatment. A response was maintained for 6 months (P ≤ 0.05 vs baseline). Both treatments were well tolerated; only mild adverse events were reported. In conclusion, for treatment of crow's feet, incobotulinumtoxinA and abobotulinumtoxinA (1:3 dose) demonstrated comparable efficacy in terms of magnitude and longevity of effect. Both products demonstrated a high responder rate, with the response being maintained for 6 months in the majority.