title: Botulinum toxin type B: pH change reduces injection pain, retains efficacy.
abstract: BACKGROUND
  Injection of botulinum toxin Type B (BTX-B) is substantially more painful than injection of botulinum toxin Type A (BTX-A).
  
  
  OBJECTIVE
  A method of reducing pain with BTX-B injection without reducing efficacy. This was evaluated in 2 BTX-A-resistant subjects and another BTX-B-naive subject.
  
  
  METHODS
  Clinical evaluation and computer analysis of photographs were used to confirm efficacy to different dilutions of Type B toxin and confirm BTX-A resistance. A pilot study of 3 subjects involves BTX-B (usually pH 5.6) that was diluted with sodium bicarbonate to normalize the pH to 7.5 in the syringe immediately before injection. Pain assessment compared the different pH BTX-B solutions.
  
  
  RESULTS
  Two patients with acquired resistance to 3 BTX-As in upper facial muscles responded to BTX-B. Injection pain of BTX-B changed to pH 7.5 was significantly reduced and retained efficacy over 10 weeks.
  
  
  CONCLUSIONS
  Botulinum toxin Type A resistance is documented to 3 BTX-A brands in 2 patients. They had received low doses of Type A toxin, they responded to Type B toxin. Injection pain of the acidic solution of BTX-B neurotoxin was reduced and efficacy not compromised by changing pH of BTX-B solution to pH 7.5. This method improved patient tolerance to BTX-B injections.
authors.affiliation: *Cranley Clinic, London, England; †UCLA School of Medicine, Los Angeles, California.
authors.forename: Philippa L
authors.initials: PL
authors.lastname: Lowe
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Lowe
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000737:chemistry*; D004351:Drug Resistance; D005145:Face; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007267:Injections; D008297:Male; D009465:Neuromuscular Agents / Q000008:administration & dosage* / Q000737:chemistry*; D010146:Pain / Q000517:prevention & control*; D010147:Pain Measurement; D010781:Photography; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; C096323:rimabotulinumtoxinB; D019274:Botulinum Toxins, Type A