title: Phase IV study comparing incobotulinumtoxinA and onabotulinumtoxinA using a 1:1.5 dose-conversion ratio for the treatment of glabellar frown lines.
abstract: BACKGROUND
  IncobotulinumtoxinA and onabotulinumtoxinA are effective treatments for glabellar frown lines, and a dose of 20 U is recommended for both preparations. However, debate continues over using the same dosages of these products, although a 1:1 dose ratio has been proven in several head-to-head clinical trials in neurological and esthetic indications.
  
  
  OBJECTIVE
  To investigate whether a 50% higher dose of onabotulinumtoxinA was nonsuperior to incobotulinumtoxinA in the treatment of glabellar frown lines in the short and long term.
  
  
  METHODS
  Subjects aged 18-65 years with symmetrical moderate-to-severe glabellar frown lines (score: ≥2 on a validated Merz 5-point scale) at maximum frown were enrolled. Corrugator muscles on both sides were treated with two injections of either 4 U incobotulinumtoxinA or 6 U onabotulinumtoxinA (equivalent to 20 and 30 U, respectively, if corrugator muscles on both sides and the procerus are treated) allowing intra-individual comparison. Glabellar frown line severity was assessed from standardized photographs every 4 weeks for 4 months and, in a subset of subjects, for up to 6 months posttreatment. The primary efficacy endpoint was the percentage of subjects with an improvement of ≥1 point on the 5-point scale at week 4. Nonsuperiority was assessed by comparing the response rates of each product.
  
  
  RESULTS
  Nonsuperiority of a 50% higher dose of onabotulinumtoxinA to that of incobotulinumtoxinA was confirmed at 4 weeks, 4 months, and 6 months posttreatment.
  
  
  CONCLUSIONS
  There is generally no reason to increase the dose of either incobotulinumtoxinA or onabotulinumtoxinA above the 20 U recommended for glabellar frown lines.
authors.affiliation: Dermatologikum, Hamburg, Germany. prager@dermatologikum.de
authors.forename: Welf
authors.initials: W
authors.lastname: Prager
authors.forename: Thomas
authors.initials: T
authors.lastname: Rappl
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000627:therapeutic use; D005138:Eyebrows; D005152:Facial Muscles / Q000187:drug effects*; D005260:Female; D005546:Forehead; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D015595:Skin Aging / Q000187:drug effects*
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A; C545476:incobotulinumtoxinA