title: Multicenter, double-blind study of the efficacy of injections with botulinum toxin type A reconstituted up to six consecutive weeks before application.
abstract: BACKGROUND
  It is recommended that botulinum toxin be used immediately or within 2 weeks after its reconstitution because its efficacy might be compromised by prolonged storage.
  
  
  OBJECTIVE
  To evaluate the efficacy of botulinum toxin type A (BTX-A) reconstituted over 6 consecutive weeks for the treatment of glabellar frown lines.
  
  
  METHODS
  Four vials of BTX-A were reconstituted each of 7 days over a period of 6 weeks, totaling 28 vials, corresponding to seven reconstitution dates. During this period, the BTX-A was stored according to the manufacturer's instructions. On the day after the last reconstitution, all of the reconstituted vials were injected in patients from four dermatologic centers taking part in this study. A total of 88 patients were treated on the same day and were followed every 2 weeks for 4 months. All patients were photographed at all stages. A number of professionals assessed the efficacy of reconstituted BTX-A based on the reduction of the maximum frowning capacity of the treated muscles.
  
  
  RESULTS
  Of the 88 patients who were selected, 3 were excluded. Three forms of evaluation were applied, and no statistically significant differences were found in the results presented.
  
  
  CONCLUSIONS
  BTX-A may be applied up to 6 weeks after reconstitution without losing its effectiveness. Other factors, which are probably individual, may influence the response to BTX-A injections.
authors.affiliation: dohexsel@zaz.com.br
authors.forename: Doris Maria
authors.initials: DM
authors.lastname: Hexsel
authors.forename: Ada Trindade
authors.initials: AT
authors.lastname: De Almeida
authors.forename: Marcio
authors.initials: M
authors.lastname: Rutowitsch
authors.forename: Inês Alencar
authors.initials: IA
authors.lastname: De Castro
authors.forename: Vera Lúcia Bauer
authors.initials: VL
authors.lastname: Silveira
authors.forename: Daniela Orso
authors.initials: DO
authors.lastname: Gobatto
authors.forename: Mônica
authors.initials: M
authors.lastname: Zechmeister
authors.forename: Rosemari
authors.initials: R
authors.lastname: Mazzuco
authors.forename: Dêbora
authors.initials: D
authors.lastname: Zechmeister
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D004311:Double-Blind Method; D004339:Drug Compounding / Q000379:methods; D004355:Drug Stability; D004356:Drug Storage / Q000379:methods*; D005260:Female; D005546:Forehead; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D015595:Skin Aging / Q000187:drug effects*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019274:Botulinum Toxins, Type A