The treatment of dynamic upper facial creases with botulinum toxin type A is sometimes characterized as a trivial procedure, one equally successful in the hands of anyone capable of holding a syringe and depressing a plunger. In fact, this procedure is surprisingly complex and replete with nuance. With this study, Abbasi et al further define the properties of different dilutions of botulinum toxin.
The specific practice gap addressed is how dilution affects effectiveness, and whether effectiveness and safety can be improved by using more dilute botulinum toxin preparations. However, in a larger context, the practice gap is not merely uncertainty about dilution, but more generally, how botulinum toxin should be deployed for cosmetic treatments. When botulinum toxin was classified by the US Food and Drug Administration as a drug, the subtleties of its use were not yet very well understood, and official guidance about dosage and administration on the package insert is consequently sparse. In practice, botulinum toxin operates with the site-specific concentration and means of delivery more important than total dose. Furthermore, as the number of routine off-label indications like forehead, crow's feet, and lower face wrinkles has grown, the question of where, what, and how to inject has only become more convoluted.