Botulinum Toxin in Aesthetic Medicine: Myths and Realities

Abstract

BACKGROUNDSeveral formulations of Botulinum toxin serotype A (BoNT-A) for aesthetic indications are available, with numbers likely to increase. Preparations are not interchangeable, based on dose unit comparisons.OBJECTIVENumerous myths and misconceptions regarding the use of BoNT-A for aesthetic indications have arisen, which this review aims to lay to rest.MATERIALS AND METHODSThis review assesses evidence for and against each of the most common myths regarding BoNT use in aesthetics.RESULTSBoNT-A neurotoxin/protein complexes are irrelevant to the toxin's therapeutic/aesthetic indications. BoNT-A neurotoxin/protein complexes do not influence movement from injection site or immunogenicity. Any relationship between neutralizing antibody formation and clinical response is complex and clinicians should consider other factors that may induce an apparent loss of clinical response. Diffusion appears predominately, perhaps exclusively, dose dependent. Careful placement and correct dosing optimizes likelihood of good outcomes. Manufacturers recommend reconstitution of products with sterile nonpreserved saline. However, compelling evidence suggests that reconstitution using preserved saline dramatically improves patient comfort without compromising efficacy. Several post-treatment instructions/restrictions are widely used despite the lack of evidence, but muscle activity after injection may be beneficial. Cooling the treatment area might hinder BoNT-A translocation and should probably be abandoned.CONCLUSIONThe existing evidence suggests that experienced users should achieve equivalent results regardless of BoNT-A formulation, but additional, well-designed, adequately powered, controlled randomized studies should be performed.

The mechanisms of action and use of botulinum neurotoxin type A in aesthetics: Key Clinical Postulates II

“…Each brand's units, short for mouse units, are based upon the LD 50 of the toxin (the median lethal dose that causes death in 50% of mice injected in the abdomen) found during preclinical evaluation 64 . Few well‐designed, controlled, randomized studies directly compare formulations of BoNT‐A 65,66 . Those that do attempt to compare brands have somewhat inconsistent and conflicting results, which may be due to a plethora of confounding variables that are difficult to control in addition to the lack of consensus regarding dose unit conversion ratios upon which they are based 18,65‐77 .…”

“…64 Few well-designed, controlled, randomized studies directly compare formulations of BoNT-A. 65,66 Those that do attempt to compare brands have somewhat inconsistent and conflicting results, which may be due to a plethora of confounding variables that are difficult to control in addition to the lack of consensus regarding dose unit conversion ratios upon which they are based. 18,[65][66][67][68][69][70][71][72][73][74][75][76][77] Generally, IncobotulinumtoxinA and OnabotulinumtoxinA may have close to a 1:1 dose equivalence ratio, but some dispute this.…”

“…There is no evidence to suggest that diffusion is influenced by differences in the molecular weight of toxin-NAP complexes, and all complexes dissociate entirely in the syringe or upon injection, regardless. Instead, diffusion depends on the number of toxin molecules injected and the local density of toxin receptors at NMJs 10,65,133. Diffusion is inversely proportional to the number of receptors at the injection site and directly proportional to the dose of toxin injected.…”

Different injection patterns of incobotulinumtoxinA for crow’s feet: a split‐face comparative study

“…Although the results from the indentation index were not significantly different, the median time until wrinkle relapse was longer for the 3‐point injection compared with that of the 6‐point injection (140 days vs. 112 days, P = 0.113). This could be explained by the fact that neurotoxin diffusion depends on an active binding component that targets receptors 21 . With the same total dosage, the 3‐point intramuscular injection provided better neurotoxin–muscle interaction compared with the 6‐point intradermal injection.…”

Global trends of botulinum toxin literature: A bibliometric analysis of botulinum toxin publications between 1975 and 2017

“…The net revenue of BoNT A application in aesthetic indications reached $199.4 million in 2016 and according to the American Society of Plastic Surgeons, a total of 15.4 million aesthetic procedures were performed during 2016 and in 7 million of which BoNT A was used. [ 12 ] According to 2017 report of ASDS, nearly 12 million cosmetic procedures were performed and BoNT A was applied in 2.1 million of which. [ 13 ] In the United States, three BoNT A formulations are available for aesthetic applications although specific aesthetic versions of BoNT A are on market in the European Union.…”