Efficacy and Safety of OnabotulinumtoxinA for the Treatment of Platysma Prominence: A Randomized Phase 2 Dose-Ranging Study.

Background: With aging, repetitive contraction of the platysma leads to an increase in platysma prominence (PP), characterized by the accentuation of vertical neck bands and blunting of the jawline contour.

Methods: This multicenter, double-blind, phase 2 study evaluated onabotulinumtoxinA treatment in adults with moderate to severe PP. Participants were randomized to receive 1 treatment of onabotulinumtoxinA low dose (LD), onabotulinumtoxinA high dose (HD), or placebo, and were followed up for 4 months. Efficacy end points were achievement of a 1 grade or greater improvement on both the left and right sides at day 14 at maximum contraction as assessed by the investigator (primary) or by participants (secondary) using validated scales. Safety was evaluated throughout.

Results: Participants in the modified intent-to-treat population ( n = 164) had a mean age of 50 years; 95.1% were women and 93.9% were White. The primary end point was met for both onabotulinumtoxinA groups, with investigator-assessed 1 grade or greater improvement in 77.8% (LD) and 88.2% (HD) versus 12.0% (placebo) of participants on day 14 ( P < 0.0001 versus placebo). Based on participant self-assessment, 75.9% (LD) and 88.2% (HD) versus 18.0% (placebo) achieved 1 grade or greater improvement on day 14 ( P < 0.0001 versus placebo). Most treatment-related adverse events were procedure-related, transient, and mild in severity. The most frequent onabotulinumtoxinA-related adverse event was neck muscle weakness, reported in the HD group.

Conclusion: OnabotulinumtoxinA was effective in improving the appearance of PP based on both investigators' and participants' ratings. Treatment was well tolerated.

Clinical Question/level Of Evidence: Therapeutic, I.