An open-label, randomized, 64-week study repeating 10-and 20-U doses of botulinum toxin type A for treatment of glabellar lines in Japanese subjects

Background Repeated botulinum toxin type A (BoNTA) treatment typifies clinical practice. The long-term safety and efficacy should be demonstrated in diverse populations. Objective To evaluate the long-term efficacy and safety of repeated BoNTA treatments of glabellar lines in Japanese subjects. Methods This randomized, multicenter, 64-week, open-label study of 363 subjects compared 10-U and 20-U of BoNTA for up to five treatments. The endpoints were the physician ratings of line severity and duration of efficacy, and subject ratings of line improvement and satisfaction. Safety assessments included adverse events, laboratory tests, and vital signs. Tests for neutralizing antibodies were conducted. Results Peak response rates (> 90%, maximal contraction) were observed at week 1 (treatment 1) and week 4 (treatments 2-5). The duration did not change with repeated treatments and was longer in the 20-U than in the 10-U group (17.1 +/- 6.58 weeks vs. 14.8 +/- 5.38 weeks; P < 0.001). Subject-assessed improvement ratings, 4 weeks' post-treatment, were significantly higher (P < 0.05) in the 20-U group. Overall satisfaction ratings were significantly higher in the 20-U group (P < 0.001). No serious adverse events occurred. Neutralizing antibodies were not detected. Conclusion Repeated treatments of glabellar lines with 10 or 20 U of BoNTA provided long-term safety and efficacy in Japanese subjects. The 20-U dose provided longer duration, greater subject satisfaction, and greater subject-rated improvement. The 20-U dose was identified as optimal for improving glabellar lines in Japanese subjects. These results apply only to the formulation of BoNTA used in this study.