title: Pain difference associated with injection of abobotulinumtoxinA reconstituted with preserved saline and preservative-free saline: a prospective, randomized, side-by-side, double-blind study.
abstract: BACKGROUND
  The Food and Drug Administration has approved the reconstitution of botulinum toxin A with preservative-free saline. Reconstitution of onabotulinumtoxinA with preserved saline has been previously reported to decrease the pain of injections. We present the first split-face study investigating differences in subjective pain when using preserved and preservative-free saline as the reconstituent of choice for abobotulinumtoxinA.
  
  
  OBJECTIVE
  To determine whether patients notice a difference in pain when injecting abobotulinumtoxinA diluted with preserved saline versus preservative-free saline.
  
  
  METHODS
  A prospective, randomized, double-blind, side-by-side trial was conducted in a private practice dermatology office in Boulder, Colorado. Twenty volunteer patients received injections on one side of their face with abobotulinumtoxinA reconstituted with preservative-free saline and with abobotulinumtoxinA reconstituted with preserved saline on the other side. Patients reported their pain on a 10-point visual analogue pain scale after each side was injected. Patients kept a diary for the first 48 hours after treatment to track any continued pain, onset of action, or adverse events. Patients were seen at a follow-up visit at 2 weeks, and any adverse events were recorded.
  
  
  RESULTS
  Ninety percent of patients reported less pain on the side injected with preserved saline than on the side injected with preservative-free saline. Pain on the preserved saline side was 60% less than on the preservative-free side. Neither the patients nor the investigators noted any difference in onset of action between the two sides.
  
  
  CONCLUSIONS
  Reconstitution of abobotulinumtoxinA with preserved saline results in significantly less pain on injection than with preservative-free saline. Preserved saline may be the reconstituent of choice for reconstitution of abobotulinumtoxinA.
authors.affiliation: Department of Dermatology, School of Medicine, University of Colorado, Denver, Colorado, USA. sallen.dsb@gmail.com
authors.forename: Shawn B
authors.initials: SB
authors.lastname: Allen
authors.forename: Neil A
authors.initials: NA
authors.lastname: Goldenberg
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000009:adverse effects*; D004311:Double-Blind Method; D004338:Drug Combinations; D005145:Face; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007267:Injections; D007552:Isotonic Solutions / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000009:adverse effects; D010146:Pain / Q000139:chemically induced / Q000175:diagnosis* / Q000517:prevention & control; D010147:Pain Measurement; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage; D011446:Prospective Studies; D012965:Sodium Chloride / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D004338:Drug Combinations; D007552:Isotonic Solutions; D009465:Neuromuscular Agents; D011310:Preservatives, Pharmaceutical; D012965:Sodium Chloride; D019274:Botulinum Toxins, Type A; C542869:abobotulinumtoxinA