title: A randomized, evaluator-blinded, two-center study of the safety and effect of volume on the diffusion and efficacy of botulinum toxin type A in the treatment of lateral orbital rhytides.
abstract: BACKGROUND
  There has been considerable discussion about the effect of the degree of dilution of botulinum toxin (BTX) but very few scientific studies.
  
  
  OBJECTIVE
  The objective was to observe as to whether a fivefold difference in concentration of BTX solution would produce a difference in clinical effect or duration of effect.
  
  
  METHODS
  Twenty individuals were enrolled at two sites and a within-subject paired-comparison study was performed on the lateral orbital area with a single injection of 5 U of BTX (BOTOX Cosmetic, Allergan Inc., Irvine, CA). The results were assessed both clinically and using a computer-assisted estimation of the degree of wrinkling.
  
  
  RESULTS
  No statistically significant differences were observed between the two sides.
  
  
  CONCLUSIONS
  This is a small study and it may be that dilution does affect BTX result. We were, however, unable to detect any difference in this study, which suggests that the degree of dilution, at least within a fivefold margin, has only a small effect on the results of BTX injection in the lateral orbital area.
authors: Department of Dermatology, University of British Columbia, Vancouver, British Columbia, Canada. alastair@carruthers.net
authors: Alastair
authors: A
authors: Carruthers
authors: Melissa
authors: M
authors: Bogle
authors: Jean D A
authors: JD
authors: Carruthers
authors: Jeffrey S
authors: JS
authors: Dover
authors: Kenneth A
authors: KA
authors: Arndt
authors: Te-Shao
authors: TS
authors: Hsu
authors: Jude
authors: J
authors: Poirier
mesh_terms: D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D001955:British Columbia; D004311:Double-Blind Method; D005148:Facial Dermatoses / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D012720:Severity of Illness Index; D015595:Skin Aging; D016896:Treatment Outcome; D014481:United States
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A