title: The efficacy and safety of a new U.S. Botulinum toxin type A in the retreatment of glabellar lines following open-label treatment.
abstract: BACKGROUND
  A new U.S. Botulinum toxin type A (BoNT-A) has been shown to be safe and effective when administered once, but there is a paucity of clinical evidence regarding long-term use.
  
  
  OBJECTIVE
  To evaluate the long-term efficacy and tolerability of repeated treatment with BoNT-A in the correction of moderate-to-severe glabellar lines. STUDY DESIGN/METHODOLOGY: Multicenter, phase 3, randomized, placebo-controlled, double-blind study comparing the efficacy of BoNT-A (50 units) with placebo upon re-treatment of glabellar lines following two-to-three cycles of open-label BoNT-A treatment in 311 patients.
  
  
  RESULTS
  At endpoint, BoNT-A produced a significantly higher proportion of responders versus placebo. The incidence of treatment-emergent adverse effects (TEAEs) was slightly lower during additional treatment cycles; the frequency was comparable between BoNT-A and placebo groups.
  
  
  CONCLUSIONS
  Multiple treatment cycles of BoNT-A were well tolerated in the majority of patients, and there was no tachyphylaxis seen during the study duration of up to 23 months.
authors.affiliation: Lasky Skin Center, Beverly Hills, CA, USA. markgrubin@aol.com
authors.forename: Mark G
authors.initials: MG
authors.lastname: Rubin
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Dover
authors.forename: Richard G
authors.initials: RG
authors.lastname: Glogau
authors.forename: David J
authors.initials: DJ
authors.lastname: Goldberg
authors.forename: Mitchel P
authors.initials: MP
authors.lastname: Goldman
authors.forename: Joel
authors.initials: J
authors.lastname: Schlessinger
mesh_terms: D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005546:Forehead; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D019233:Retreatment; D015595:Skin Aging / Q000187:drug effects*; D016896:Treatment Outcome; D014481:United States
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A