Botulinum Toxin in Aesthetic Medicine: Myths and Realities.

BACKGROUND: Several 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. OBJECTIVE: Numerous myths and misconceptions regarding the use of BoNT-A for aesthetic indications have arisen, which this review aims to lay to rest. MATERIALS AND METHODS: This review assesses evidence for and against each of the most common myths regarding BoNT use in aesthetics. RESULTS: BoNT-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. CONCLUSION: The 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.

Key Parameters for the Use of AbobotulinumtoxinA in Aesthetics: Onset and Duration.

Time to onset of response and duration of response are key measures of botulinum toxin efficacy that have a considerable influence on patient satisfaction with aesthetic treatment. However, there is no overall accepted definition of efficacy for aesthetic uses of botulinumtoxinA (BoNT-A). Mechanical methods of assessment do not lend themselves to clinical practice and clinicians rely instead on assessment scales such as the Frontalis Activity Measurement Standard, Frontalis Rating Scale, Wrinkle Severity Scale, and Subject Global Assessment Scale, but not all of these have been fully validated. Onset of activity is typically seen within 5 days of injection, but has also been recorded within 12 hours with abobotulinumtoxinA. Duration of effect is more variable, and is influenced by parameters such as muscle mass (including the effects of age and sex) and type of product used. Even when larger muscles are treated with higher doses of BoNT-A, the duration of effect is still shorter than that for smaller muscles. Muscle injection technique, including dilution of the toxin, the volume of solution injected, and the positioning of the injections, can also have an important influence on onset and duration of activity. Comparison of the efficacy of different forms of BoNT-A must be made with the full understanding that the dosing units are not equivalent. Range of equivalence studies for abobotulinumtoxinA (Azzalure; Ipsen Limited, Slough UK/Galderma, Lausanne CH/Dysport, Ipsen Biopharm Limited, Wrexham UK/Galderma LP, Fort Worth, TX) and onabotulinumtoxinA (Botox; Allergan, Parsippany, NJ) have been conducted, and results indicate that the number of units of abobotulinumtoxinA needs to be approximately twice as high as that of onabotulinumtoxinA to achieve the same effect. An appreciation of the potential influence of all of the parameters that influence onset and duration of activity of BoNT-A, along with a thorough understanding of the anatomy of the face and potency of doses, are essential to tailoring treatment to individual patient needs and expectations.

AbobotulinumtoxinA: A 25-Year History.

During the late 1960s and early 1970s, Alan Scott showed that intramuscular injections of botulinum toxin (BoNT) corrected nonaccommodative strabismus without resorting to surgery. The UK doctors who trained with Scott soon realized the significant potential offered by BoNT type A as a therapeutic option for several difficult-to-treat diseases. This led to a collaboration between these pioneering clinicians and the Centre for Applied Microbiology and Research at Porton Down, United Kingdom, and, in turn, to the development and commercialization of abobotulinumtoxinA as Dysport (Dystonia/Porton Down; Ipsen Biopharm Ltd., Wrexham, UK). Dysport was approved in Europe for the treatment of specific dystonias in December 1990 and now has marketing authorizations in 75 countries. Since then, the use of BoNT in therapeutic and aesthetic indications has grown year-on-year, and continues to expand well beyond Scott's initial aim. For example, ongoing trials are assessing potential new indications for BoNT-A, including acne and psoriasis. Furthermore, a growing number of other BoNT products, often termed "biosimilars," together with innovative formulations of well-established BoNT types, are likely to reach the market over the next few years. This review focuses on the history of Dysport to mark the 25th anniversary of its first launch in the United Kingdom.

The Use of Botulinum Neurotoxin Type A in Aesthetics: Key Clinical Postulates.

BACKGROUND: The most common aesthetic procedure performed worldwide is the injection of botulinum neurotoxin Type A (BoNT-A). Aesthetic providers must fully comprehend the objective scientific data, theoretical mechanisms of action, and differences between brands of BoNT-A. OBJECTIVE: To determine and review the relevant clinical postulates for the use of botulinum toxin in aesthetics. MATERIALS AND METHODS: The BoNT-A clinical postulates presented here discuss how each brand of BoNT-A acts identically, how the molecular potency may vary between the different products, how patient age, gender, genetics, and muscle mass cause variation in toxin receptor number and density, and how both practitioner and patient can affect toxin distribution. RESULTS: A total of 8 clinical postulates have been identified that are key to understanding the use of botulinum toxin in aesthetics and to obtaining the best clinical results. CONCLUSION: All of these factors affect the potential efficacy of the injected toxin and hence the aesthetic results obtained.

Recommendations for the best possible use of botulinum neurotoxin type a (Speywood units) for aesthetic applications.

The botulinum neurotoxin (BoNT) product Azzalure (manufactured by Ipsen Biopharm Limited, Wrexham, UK; distributed by Galderma), measured in Speywood units (s.U) has been available since 2009 for temporary improvement in the appearance of moderate to severe glabellar lines. Although we know much about the use of Azzalure for aesthetic indications, some aspects of product use in the clinic still require an update based on continuing and prevailing misconceptions and new clinical data. Therefore, a group of experts experienced with the use of Azzalure convened to formulate the following recommendations: (1) The key to an optimal effect is adequate dosing per injection point. Ten s.U are indicated for strong muscular activity, 5 s.U for medium activity, and approximately 2 s.U for minor activity. (2) The main factor that influences the area of effectiveness is the dosage per injection point. (3) In contrast to former beliefs, we know now that Azzalure works very fast, with some patients reporting initial drug activity after hours. (4) Various volumes can be used for dilution. However, the first choice is the recommended volume, 0.63 mL per vial of 125 s.U. Nevertheless, for clinicians changing products, keeping the volume they are used to might be an option. (5) Clinicians changing products have to be very careful not to confuse the units between different products. (6) In aesthetic BoNT-A usage, the development of antibodies is very rare and is not the common reason for insufficient results. (7) Probably the most common reason when BoNT-A is not working is the absolute or relative underdosage. The present adjunctive recommendations elaborated in an informal expert meeting should help physicians to optimize their treatment with Speywood unit products.

The botulinum toxin LD50 potency assay - another chapter, another mystery.

Observers of the potency assay used for botulinum toxin were greeted last year with the news that one company had an alternative, non-animal alternative in place. But all was not as it seemed from the press release, and over a year later, information is still lacking.

Towards new uses of botulinum toxin as a novel therapeutic tool.

The uses of botulinum toxin in the fields of neurology, ophthalmology, urology, rehabilitation medicine and aesthetic applications have been revolutionary for the treatment of patients. This non-invasive therapeutic has continually been developed since first discovered in the 1970s as a new approach to what were previously surgical treatments. As these applications develop, so also the molecules are developing into tools with new therapeutic properties in specific clinical areas. This review examines how the botulinum toxin molecule is being adapted to new therapeutic uses and also how new areas of use for the existing molecules are being identified. Prospects for future developments are also considered.