Duration and onset of effect of incobotulinumtoxinA for the treatment of blepharospasm in botulinum toxin-naïve subjects.

PLAIN LANGUAGE SUMMARYBlepharospasm is a condition in which involuntary contractions of the eyelid muscles cause the eye to close. The condition can be treated with botulinum neurotoxin type A (BoNT-A) injections. This study assessed the duration of effect and time to onset of effect for the BoNT-A formulation incobotulinumtoxinA (Xeomin, Merz Pharmaceuticals GmbH) in adults with blepharospasm. Subjects received a single injection of one of two doses of incobotulinumtoxinA (total dose 25 or 50 U) or placebo and received a second injection of incobotulinumtoxinA only (total dose ≤70 U; the second injection was not compared with placebo) if needed 6­20 weeks after the first injection. After the first injection, the median (mid-point of values from all subjects) duration of treatment effect was longer with the higher incobotulinumtoxinA dose (20 weeks) than with the lower dose (11 weeks) and was longer with both incobotulinumtoxinA doses than with placebo (6 weeks). After the second incobotulinumtoxinA injection, the median duration of treatment effect was 20 weeks. The time to onset of effect was quicker with both incobotulinumtoxinA doses (5 and 7 days for the higher and lower doses, respectively) than with placebo (14 days) and the difference was statistically significant for the higher incobotulinumtoxinA dose compared with placebo. The time to waning of treatment effect was similar for the two incobotulinumtoxinA doses and placebo. This study shows that incobotulinumtoxinA is an effective treatment for blepharospasm, with a fast onset of action. In addition, the effects of one injection can last for up to 20 weeks.