title: Respective potencies of Botox and Dysport: a double blind, randomised, crossover study in cervical dystonia.
abstract: OBJECTIVE
  Botulinum toxin type A is a potent neuromuscular paralyzing agent used in various disorders including cervical dystonia. Two preparations of botulinum toxin are now commercially available ( Dysport and Botox), but much controversy remains about their respective potencies. The aim of the study was to compare the efficacy of Botox with two different ratios of Dysport.
  
  
  METHODS
  A double blind, randomised, three period cross over study involving 54 patients with cervical dystonia was performed. The patients received the following treatments in a randomised order: Botox at the usually effective dose, Dysport at a dose of 1:3 (conversion factor of 3 between Botox and Dysport units-that is, one Botox unit=three Dysport units) and at a dose of 1:4 (conversion factor of four). The improvement of the Tsui (primary outcome criteria) and of the TWSTRS pain scales between baseline and a control visit 1 month after each of the three injections, as well as the incidence of adverse events, were assessed.
  
  
  RESULTS
  Comparison of the Tsui scores and of the TWSTRS pain scores showed a better effect on impairment and pain with Dysport 1:3 (p=0.02 and 0.04, respectively) and 1:4 (p=0.01 and 0.02, respectively) than with Botox. The number of adverse events was higher with both Dysport treatments. The most frequent adverse event was dysphagia, found in 3%, 15.6%, and 17.3% (Botox, Dysport 1:3 and 1:4, respectively) of the patients. No adverse event required withdrawal of therapy or specific management.
  
  
  CONCLUSIONS
  Dysport 1:3 (and Dysport 1:4 to a greater extent) is more efficient than Botox for both impairment and pain in cervical dystonia although with a somewhat higher incidence of minor adverse effects. This strongly suggests that the most appropriate conversion factor between Botox and Dysport units is less than 3 in cervical dystonia.
authors.affiliation: Service de Neurologie, Hôf.pital Sainte-Anne, Paris, France. ranoux@chsa.broca.inserm.fr
authors.forename: D
authors.initials: D
authors.lastname: Ranoux
authors.forename: C
authors.initials: C
authors.lastname: Gury
authors.forename: J
authors.initials: J
authors.lastname: Fondarai
authors.forename: J L
authors.initials: JL
authors.lastname: Mas
authors.forename: M
authors.initials: M
authors.lastname: Zuber
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy / Q000209:etiology; D013810:Therapeutic Equivalency; D014103:Torticollis / Q000188:drug therapy*
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A