title: Botulinum toxin type B for dynamic glabellar rhytides refractory to botulinum toxin type A.
abstract: BACKGROUND
  Botulinum toxin type B (BTX-B; Myobloc) has recently been introduced for the treatment of dynamic rhytides. This serotype is structurally similar to botulinum toxin type A (BTX-A; Botox) and appears to produce equivalent muscular paralysis. Because of the fact that some patients may become resistant to the effects of BTX-A with its continued use or may require large doses of type A to exert adequate muscular paralysis, the use of BTX-B may prove beneficial in these cases.
  
  
  OBJECTIVE
  To determine the effect of BTX-B on glabellar rhytides refractory or showing decreased clinical effect to treatment with BTX-A.
  
  
  METHODS
  Twenty females (mean age, 43 years) with vertical glabellar rhytides showing decreased or negligible clinical effect to BTX-A were treated with intramuscular injections of BTX-B. Five standardized intramuscular sites (procerus, inferomedial corrugator muscles, superior middle corrugator muscles) received a total dose of 2,500 U. Patients were evaluated at pretreatment and 48 to 72 hours, 1 week, and 2 and 4 months after injection.
  
  
  RESULTS
  All glabellar rhytides improved after treatment with BTX-B injections. Peak clinical effect was noted 1 month after treatment, with 50% of peak effect evident at the 2-month follow-up. Near complete dissolution of effect was seen at 4 months after treatment. Side effects were transient and were limited to moderate injectional pain and rare bruising and frontal brow tightness.
  
  
  CONCLUSIONS
  BTX-B is an effective treatment modality for glabellar rhytides refractory or exhibiting decreased clinical effect to BTX-A. The duration of effect using the 2,500 U dosing schedule described herein was shorter than that typically achieved after equivalent BTX-A injection.
authors.affiliation: Washington Institute of Dermatologic Laser Surgery, Washington, DC, USA. talster@skinlaser.com
authors.forename: Tina S
authors.initials: TS
authors.lastname: Alster
authors.forename: Jason R
authors.initials: JR
authors.lastname: Lupton
mesh_terms: D000328:Adult; D001905:Botulinum Toxins / Q000008:administration & dosage*; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D005260:Female; D005546:Forehead; D006801:Humans; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D015595:Skin Aging / Q000187:drug effects*; D017211:Treatment Failure
chemical_list: D009465:Neuromuscular Agents; C096323:rimabotulinumtoxinB; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A