Long-term safety of abobotulinumtoxinA for the treatment of glabellar lines: results from a 36-month, multicenter, open-label extension study.

BACKGROUND: Because abobotulinumtoxinA treatment for glabellar lines must be repeated regularly to prevent recurrence, understanding the safety and effectiveness of long-term, repeated administration of abobotulinumtoxinA is important.

OBJECTIVE: To report the long-term safety and efficacy of abobotulinumtoxinA in patients with moderate to severe glabellar lines.

METHODS AND MATERIALS: AbobotulinumtoxinA was administered to 1,415 patients in multiple cycles over 24 months as a fixed dose of 50 U or as a dose based on muscle mass and sex (women: 50-70 U; men: 60-80 U). Adverse events were assessed after each visit on days 7, 14, and 30 and monthly thereafter; monitoring continued every 3 months for a total safety monitoring duration of 36 months or less.

RESULTS: Nine hundred ninety-one (70%) patients reported treatment-emergent adverse effects (TEAEs); most events were mild (70%) or moderate (20%) in severity. The rate of TEAEs did not increase over 24 months of repeated treatment (mean 5.6 cycles; range 1-9). Treatment-related eyelid ptosis followed 53 of 7,938 (0.7%) treatments, all of which resolved spontaneously.

CONCLUSIONS: Multiple cycles of abobotulinumtoxinA treatment over 24 months were well tolerated and effective for the correction of glabellar lines, with no evidence of cumulative safety problems.