A randomized, evaluator-blinded, two-center study of the safety and effect of volume on the diffusion and efficacy of botulinum toxin type A in the treatment of lateral orbital rhytides

Background There has been considerable discussion about the effect of the degree of dilution of botulinum toxin (BTX) but very few scientific studies. Objective The objective was to observe as to whether a fivefold difference in concentration of BTX solution would produce a difference in clinical effect or duration of effect. Methods and Materials Twenty individuals were enrolled at two sites and a within-subject paired-comparison study was performed on the lateral orbital area with a single injection of 5 U of BTX (BOTOX Cosmetic, Allergan Inc., Irvine, CA). The results were assessed both clinically and using a computer-assisted estimation of the degree of wrinkling. ResultsNo statistically significant differences were observed between the two sides. Conclusions This is a small study and it may be that dilution does affect BTX result. We were, however, unable to detect any difference in this study, which suggests that the degree of dilution, at least within a fivefold margin, has only a small effect on the results of BTX injection in the lateral orbital area.