Bilateral, double-blind, randomized comparison of 3 doses of botulinum toxin type A and placebo in patients with crow's feet

Background: Optimum dosing for botulinum toxin type A (BTX-A) in crow's feet remains to be defined. Objective: Our purpose was to compare the efficacy and safety of 3 doses of BTX-A and placebo in patients with crow's feet. Methods: Patients were treated with 6, 12, or 18 units of BTX-A in orbicularis oculi muscle on one side and placebo contralaterally (double-blind design). At 16 weeks after injection, patients were treated with 12 or 18 units of BTX-A bilaterally (open-label design). Trained observers and patients rated the wrinkles on a scale of 0 (none) to 3 (severe) at maximum contraction and repose and at baseline and 4-week intervals over a 16-week period after injection. Results: All doses of BTX-A were significantly superior to placebo with no clear dose-response relationship. Benefits of the second injection lasted longer than the first. Few and mild adverse events were seen. Conclusion: BTX-A is a safe and effective treatment for crow's feet. Benefits are more sustained with repeat treatment.