title: A prospective, double-blind, randomized, parallel- group, dose-ranging study of botulinum toxin type a in female subjects with horizontal forehead rhytides.
abstract: BACKGROUND
  Botulinum toxin type A is used cosmetically to improve facial lines, but it has not been thoroughly investigated for the treatment of horizontal forehead rhytides.
  
  
  OBJECTIVE
  To compare the efficacy and safety of three doses of botulinum toxin type A in females with horizontal forehead rhytides and to establish whether the response rate and the duration of response are dose dependent.
  
  
  METHODS
  Fifty-nine female patients with horizontal forehead rhytides scoring 2 (moderate) or 3 (severe) on the facial wrinkle scale (FWS) were randomly assigned to receive 16, 32, or 48 U of botulinum toxin type A (BOTOX, BOTOX Cosmetic; Allergan, Irvine, CA), which was administered to eight injection sites. Half of the dose was administered to the brow depressors and the other half to the elevators. Wrinkle severity was assessed by the investigator and patient using the FWS at baseline, at Weeks 2 and 4, and then every 4 weeks for 48 weeks.
  
  
  RESULTS
  Improvements in horizontal rhytides were observed in all dosage groups. Significant dose-response trends were observed for rate of improvement at maximum brow elevation (53% in the 48-U group vs. 15% in the 16-U group at 16 weeks) and rate of relapse to baseline (35% in the 48-U group vs. 75% in the 16-U group at 16 weeks) by a trained observer.
  
  
  CONCLUSIONS
  Higher botulinum toxin type A doses resulted in greater efficacy and longer duration of effect in the reduction of horizontal rhytides.
authors.affiliation: Division of Dermatology, Vancouver, British Columbia, Canada. alastair@carruthers.net
authors.forename: Alastair
authors.initials: A
authors.lastname: Carruthers
authors.forename: Jean
authors.initials: J
authors.lastname: Carruthers
authors.forename: J
authors.initials: J
authors.lastname: Cohen
mesh_terms: D000293:Adolescent; D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005546:Forehead; D006801:Humans; D008875:Middle Aged; D009122:Muscle Hypertonia; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D012647:Self-Assessment; D015595:Skin Aging / Q000187:drug effects*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A