Botulinum Toxin in Aesthetic Medicine: Myths and Realities

The Effect of Climate on the Dose Requirements of Botulinum Toxin A in Cosmetic Interventions

BACKGROUND

Botulinum toxin A to the glabella is a popular cosmetic intervention. Functional musculature differences may arise from chronic behavioral adjustment to high sun exposure levels, requiring greater doses. This could affect clinical practice globally. This study investigated the effect of climate on real-world doses.

METHODS

The authors conducted a comparative cohort study using data from a registry from a single provider practicing across two centers: the United Kingdom and Malta. They classified one center as low sun exposure (United Kingdom winter month treatment) and the other as high sun exposure (Malta summer months). Patients were followed up once every 3 weeks and received top-up doses until full clinical paralysis was achieved. To standardize the comparison, the study included only women aged 35 to 60 years undergoing glabellar botulinum toxin treatment by experienced clinicians following standard procedures from 2012 to 2019. Smokers, those not seeking maximal paralysis, those documented as not compliant with posttreatment advice, those with colds or fevers, and those with broken cold supply chains were excluded. Univariable and multivariable analyses were undertaken.

RESULTS

A total of 523 patients were included: 292 "high-sun" patients and 231 "low-sun" patients. Mean total doses were significantly higher in the high-sun group (29.2 units versus 27.3 units; P = 0.0031). When correcting for age in multivariable analysis, the low-sun group still had lower total dose requirements ( P = 0.00574).

CONCLUSION

Patients injected with glabellar botulinum toxin in high-sun climates may have significantly increased dose requirements to achieve maximal paralysis.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Estimating the Change in Facial Subunits During Positive and Negative Facial Expression Using Three-Dimensional Stereophotogrammetry Facial Analysis

Background: A more refined and clinically related facial expression analysis is required for patients who wish to be perceived more emotionally positive. Objective: To measure the change in skin vector and volume in facial subunits when expressing positive expression (happiness) compared with negative expressions (sadness, fear, disgust, and anger), using three-dimensional (3D) stereophotogrammetry analysis. Methods: This study took 3D photographs of 20 volunteers' face at rest and during positive and negative expression. The directions of skin vector and volume changes in each facial subregion were recorded and calculated. Results: In the positive expression, 78.3% (95% confidence interval [CI] 66.8-89.9) of the medial midfacial subregions presented superolateral vector and volume increase, whereas volume decrease in 82.5% (95% CI 78.5-86.5) of the lip subregions could be observed. In the negative expression, the vector changes were predominantly inferomedial in 26.0% (95% CI 15.4-36.5) of the forehead and 36.8% (95% CI 33.2-40.3) of the upper eyelid subregions, whereas volume increases in 34.0% (95% CI 30.4-37.7) of the upper eyelid subregions were observed. Conclusions: This 3D stereophotogrammetry analysis presents the morphological difference between the positive and negative expression.

Neuromodulator Assessment and Treatment for the Upper Face: An Update

Neuromodulator treatment of the upper face has been extensively studied and serves as an excellent tool to enhance facial appearance, non-verbal communication, and social functioning. Optimal outcomes are best achieved when health care providers take an individualized approach, based on knowledge of structural and functional anatomy, thorough facial assessment, and customized injection techniques and patterns.

Tailored Indications for Different Neurotoxins

Background

Minimally invasive procedures have become increasingly popular because they require minimal downtime and are effective for achieving a more youthful appearance. All U.S. Food and Drug Administration-approved neurotoxins are indicated for achieving similar effects, even though they are different in regard to structure, manufacturing technique, and storage requirements. It is agreed upon that each neurotoxin is unique and therefore not interchangeable. The aim of the author is to provide an approach for choosing the optimal toxin in different indications regarding the area of treatment, the age and characteristics of the patient, potential risks, and ultimate goals.

Methods

As the country that the author practices carries onabotulinum (ONA), prabotulinum (PRA), and abobotulinum (ABO) toxin type-A, one of these three toxins was preferred for each category. ABO toxins were preferred in wide areas due to the broader action halo. Typical examples include hyperhidrosis treatment, wide forehead area, and calf slimming. In areas where very precise and targeted treatment is required, PRA and ONA toxins were preferred to limit potential side effects due to wider diffusion. First-time patients were typically treated with PRA toxins for a softer trial periods where as "repeat" patients were successfully treated with ABO toxins.

Results

No toxin is superior to the other in terms of producing effects. Yet, small differences in their properties can allow the plastic surgeon to cater to each patient's needs while yielding the most optimal results.

Conclusions

This study is meant to serve as a guideline for choosing the ideal toxin in different patient settings and indications.

Office-based facial plastics procedures: Neuromodulators

Botulinum toxin is a potent neuromodulator commonly used for cosmetic applications in the clinic. In this article, we reviewed the various formulations of botulinum toxin type A commercially available in the United States, as well as clinical pearls for preprocedural planning, common in-office injections, and management of complications.

Biology activity and characterization of the functional L-HN fragment derivative of botulinum neurotoxin serotype E

OBJECTIVES

The mature botulinum neurotoxin (BoNT) is a long peptide chain consisting of a light chain (L) and a heavy chain (H) linked by a disulfide bond, where the heavy chain is divided into a translocation domain and an acceptor binding domain (Hc). In this study, we further explored the biology activity and characteristics of recombinant L-HN fragment (EL-HN) composed of the L and HN domains of BoNT/E in vivo and in vitro.

METHODS

Neurotoxicity of L-HN fragments from botulinum neurotoxins was assessed in mice. Cleavage of dichain EL-HN in vitro and in neuro-2a cells was assessed and compared with that of single chain EL-HN. Interaction of HN domain and the receptor synaptic vesicle glycoprotein 2C (SV2C) was explored in vitro and in neuro-2a cells only expressing SV2C.

RESULTS

We found that the 50% mouse lethal dose of the nicked dichain EL-HN fragment (EL-HN-DC) was 0.5 μg and its neurotoxicity was the highest among the L-HN's of the four serotypes of BoNT (A/B/E/F). The cleavage efficiency of EL-HN-DC toward synaptosome associated protein 25 (SNAP25) in vitro was 3-fold higher than that of the single chain at the cellular level, and showed 200-fold higher animal toxicity. The EL-HN-DC fragment might enter neuro-2a cells via binding to SV2C to efficiently cleave SNAP25.

CONCLUSIONS

The EL-HN fragment showed good biological activities in vivo and in vitro, and could be used as a drug screening model and to further explore the molecular mechanism of its transmembrane transport.

High Levels of Physical Activity Reduce the Esthetic Durability of Botulinum Toxin Type A: A Controlled Single-Blind Clinical Trial

The present study aimed to evaluate the influence of physical activity on the durability of the esthetic effect of botulinum toxin type A (BoNT-A). Sixty female patients were allocated to three groups (n = 20) according to their physical activity level (PA): Low PA, Moderate PA, and High PA. All groups received a single injection of onabotulinumtoxinA, considering standardized doses in the frontalis (12U), corrugator supercilia (7U, each), and procerus muscles (4U). Outcomes were measured using electromyography (EMG), Merz 5-point scales, and Face-Q scales (perceived age and lines between eyebrows). A follow-up occurred after 30, 60, and 90 days. EMG results showed a significant decrease in muscle activity in the Low-PA group at all follow-ups compared with the other groups (p < 0.001). The Merz scale scores showed that the severity of forehead and glabellar lines significantly improved in the Low-PA group throughout this study compared with the other groups (p < 0.001). No significant differences between groups were found in the Face-Q scale for perceived age, while the Face-Q scale for lines between eyebrows showed better results for Low-PA (p < 0.01) and Moderate-PA (p < 0.01) groups compared to the High-PA group at the 30- and 90-day follow-ups. The durability of the esthetic effect of BoNT-A seems to be negatively influenced by the level of physical activity.

Dermatological Management of Aged Skin

The subject of the work concerns the dermatological management of patients mainly with aged skin. The purpose of the work was to present the basic techniques and preparations which are performed by dermatologists in the treatment of aged skin. There are dermatological treatments related to the treatment of skin diseases and cosmetic treatments which are mainly related to skin care. In this work, the method of literature research was applied. On the basis of books and journal articles on dermatological and cosmetic procedures for aged skin, an analysis of treatment types was made. Then, the results of this analysis were presented in the paper under discussion. The paper presents information on the skin and its properties. The structure and functions of the skin, aging processes and characteristics of aged skin were discussed. Then, the possibilities of reducing the visible signs of skin aging through the use of invasive and non-invasive dermatological and cosmetological treatments were given, and the most important components of preparations used supportively in combating skin aging processes were discussed.

Cosmetic Treatment Using Botulinum Toxin in the Oral and Maxillofacial Area: A Narrative Review of Esthetic Techniques

Botulinum toxin (BoNT) is an anaerobic rod-shaped-neurotoxin produced by Clostridium botulinum, that has both therapeutic and lethal applications. BoNT injection is the most popular cosmetic procedure worldwide with various applications. Patients with dynamic wrinkles in areas such as the glabella, forehead, peri-orbital lines, nasal rhytides, and perioral rhytides are indicated. Excessive contraction of muscles or hyperactivity of specific muscles such as bulky masseters, cobble stone chins, gummy smiles, asymmetric smiles, and depressed mouth corners can achieve esthetic results by targeting the precise muscles. Patients with hypertrophic submandibular glands and parotid glands can also benefit esthetically. There are several FDA-approved BoNTs (obabotuli-numtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, letibotulinumtoxinA, prabotulinumtox-inA, daxibotulinumtoxinA, rimbotulinumtoxinB) and novel BoNTs on the market. This paper is a narrative review of the consensus statements of expert practitioners and various literature on the injection points and techniques, highlighting both the Asian and Caucasian population separately. This paper can serve as a practical illustrative guide and reference for optimal, safe injection areas and effective doses for application of BoNT in the face and oral and maxillofacial area. The history of BoNT indications, contraindications, and complications, and the merits of ultrasonography (US)-assisted injections are also discussed.

Emerging Trends in Botulinum Neurotoxin A Resistance: An International Multidisciplinary Review and Consensus

Botulinum neurotoxin A (BoNT-A) injection is the most widely performed aesthetic procedure and a first-line therapeutic option for various medical conditions. The potential for BoNT-A immunoresistance and secondary nonresponse related to neutralizing antibody (NAb) formation warrants attention as the range of BoNT-A aesthetic applications continues to expand.

Methods

An international multidisciplinary panel reviewed published evidence on BoNT-A immunoresistance in aesthetic and therapeutic applications and discussed best practices integrating clinical, ethical, and aesthetic considerations. Consensus statements relating to awareness, assessment, and management of the risk of NAb-related secondary nonresponse in aesthetic practice were developed.

Results

There was a consensus that, as doses used in aesthetic practice become like those in therapeutics, rates of NAb formation may be expected to increase. However, the true extent of NAb formation in aesthetics is likely underestimated due to limitations of published evidence and variability in treatment patterns of aesthetic patients. Since BoNT-A therapy is often lifelong, practitioners need to recognize immunogenicity as a potential complication that might affect future therapeutic use and strive to minimize modifiable risk factors. The selection and use of a BoNT-A product with the least immunogenic potential from the beginning may thus be advantageous, especially when treatment with high doses is planned.

Conclusions

In view of current trends in BoNT-A aesthetic use, it is essential for practitioners to conduct thorough clinical assessments, inform patients of treatment risks, and develop BoNT-A treatment plans to minimize immunogenicity. This can help preserve the option of continued or future BoNT-A treatment with satisfactory outcomes.

Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update

Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.

Use of Botulinum Toxin for Androgenic Alopecia: A Systematic Review

In this systematic review, we summarize the efficacy and safety of intradermal and intramuscular botulinum toxin injections for androgenic alopecia (AGA). Using PubMed, we conducted a literature search up to February 2021 using the following keyword combinations: "botulinum toxin" or "botox" and "androgenetic alopecia," "hair loss," or "alopecia." Five clinical studies met our inclusion criteria: 4 prospective cohorts and 1 randomized clinical trial (RCT). Study durations ranged from 24 to 60 weeks. No studies included control groups or compared botulinum toxin injections against approved treatments. A total of 165 participants were identified - all of whom were males with AGA. Of the 4 studies measuring response rates (i.e., subjects with >0% hair changes), response rates ranged from 75 to 79.1%. Within studies measuring hair count changes from intramuscular injections, changes ranged from 18 to 20.9%. No serious adverse events were reported. Studies on botulinum toxin injections have produced favorable outcomes for AGA subjects. However, results should be interpreted with caution due to the absence of control groups, small numbers of participants, and relatively low Jadad quality scores. Large RCTs are recommended to confirm efficacy and safety, explore the effects of botulinum toxin on females with pattern hair loss, and establish best practices for intradermal and intramuscular injection methodologies.

Long-term Efficacy and Safety of Liquid AbobotulinumtoxinA Formulation for Moderate-to-Severe Glabellar Lines: A Phase III, Double-Blind, Randomized, Placebo-Controlled and Open-Label Study

BACKGROUND

A ready-to-use liquid formulation of abobotulinumtoxinA (aboBoNT-A solution) has been developed.

OBJECTIVES

The aim of this study was to assess the long-term efficacy and safety of aboBoNT-A solution for the treatment of glabellar lines.

METHODS

This was a multicenter, multinational, Phase III study (NCT02493946), with randomized double-blind placebo-controlled (DBPC; 2:1 aboBoNT-A solution 50 U/placebo) and open-label (4 cycles aboBoNT-A solution) periods; additional patients were recruited into the open-label period. Patients were 18 to 65 years old, BoNT-naïve, and dissatisfied/very dissatisfied with moderate/severe glabellar lines at maximum frown. Investigator's live assessment (primary endpoint)/subject's self-assessment of glabellar line severity at maximum frown, patient satisfaction with glabellar line appearance, and FACE-Q patient-reported scales (facial appearance overall, psychological well-being, aging) were assessed. Adverse events were monitored. Analyses were performed on DBPC and long-term analysis (LTA; all patients receiving ≥1 aboBoNT-A solution injection) populations.

RESULTS

Responder rates for the investigator's live assessment, the subject's self-assessment, and patient satisfaction were consistent at Day 29 postinjection across repeat LTA cycles (82.2%-87.8%, 62.8%-80.6%, and 72.2%-87.8%, respectively), with statistically significantly higher responder rates vs placebo (DBPC cycle: 81.6% vs 0.8%, 68.1% vs 2.3%, and 83.1% vs 5.7%, respectively; all P < 0.0001). Consistent improvements on FACE-Q scales occurred with repeat cycles (DBPC cycle: aboBoNT-A solution vs placebo, P < 0.0001). No new or unexpected adverse events, or neutralizing antibodies, were observed.

CONCLUSIONS

These results support the long-term efficacy and safety of aboBoNT-A solution, and its superiority over placebo, for treatment of glabellar lines in adults.

LEVEL OF EVIDENCE: 1

Botulinum Toxin Type A: Adverse Events and Management

Aesthetic medicine is witnessing an increasing exploitation of all the procedures. The demand has never been higher than it is today. The number of practitioners is also increasing year by year. Consequently complications and other kinds of related troubles and procedures are also rising. Never like today is fundamental, in case of troubles, how to properly manage with the most frequent issues. In aesthetic medicine field, botulinum toxin procedures are the safest. Lot of patients are worried about botulinum toxin despite the available scientific literature. Rare short-term complications are observed. In the most of cases, nothing severe occurs if the international recommendations and the most recent guidelines are closely followed, the majority of them are injection related. This study is a review of rare or common problems that can occur and how to manage or solve the situations.

Creating Lift in the Lower Face With Botulinum Toxin A Treatment: An Anatomical Overview With Videos and Case Studies Illustrating Patient Evaluation and Treatment

Background

Relaxation of depressor muscles in the lower face with botulinum toxin A (BoNT-A) can create a lifting effect and dramatically improve jawline contour and resting facial expression. Even with the recent increase in interest in lower face rejuvenation, BoNT-A is a relatively under-recognized tool for treatment of this area. When treating the lower face, an understanding of anatomy and the relationship between the facial muscles is especially important, as injection patterns must be customized for consistently positive outcomes.

Objectives

This study was aimed to provide basic knowledge of the activities of the muscles in the lower face and neck and to describe the basis for injecting BoNT-A to create lift in this area. Expert guidance for injection is also provided.

Methods

As part of a continuing medical education course on differentiating botulinum toxin products, a panel of 4 expert physician injectors participated in a live webinar to discuss the implications of increasing toxin use.

Results

The practical guidance in this manuscript is based on the most frequently requested information by audience members and the information considered critical for success by the authors. The authors outline the functional anatomy of the lower face most relevant for BoNT-A treatment and case studies as well as methods for patient evaluation and injection technique are also provided. Videos showing treatment planning and injection technique for the lower face and neck are included.

Conclusions

BoNT-A is an important nonsurgical tool for creating lift in the lower face.

Level of Evidence 5

Immunogenicity of Botulinum Toxin Formulations: Potential Therapeutic Implications

Botulinum neurotoxins (BoNTs) are proteins produced by bacteria of the Clostridium family. Upon oral ingestion, BoNT causes the neuroparalytic syndrome botulism. There are seven serotypes of BoNT (serotypes A-G); BoNT-A and BoNT-B are the botulinum toxin serotypes utilized for therapeutic applications. Treatment with BoNT injections is used to manage chronic medical conditions across multiple indications. As with other biologic drugs, immunogenicity after long-term treatment with BoNT formulations may occur, and repeated use can elicit antibody formation leading to clinical nonresponsiveness. Thus, approaching BoNT treatment of chronic conditions with therapeutic formulations that minimize stimulating the host immune response while balancing patient responsiveness to therapy is ideal. Immunogenicity is a clinical limitation in many settings that use biologic drugs for treatment, and clinically relevant immunogenicity reduction has been achieved through engineering smaller protein constructs and reducing unnecessary formulation components. A similar approach has influenced the evolution of BoNT formulations. Three BoNT-A products and one BoNT-B product have been approved by the Food and Drug Administration (FDA) for therapeutic use: onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB; a fourth BoNT-A product, daxibotulinumtoxinA, is currently under regulatory review. Additionally, prabotulinumtoxinA is a BoNT-A product that has been approved for aesthetic indications but not therapeutic use. Here, we discuss the preclinical and clinical immunogenicity data that exist within the scientific literature and provide a perspective for considering immunogenicity as a key factor in choice of BoNT formulation.

High-Dose Neuromodulators: A Roundtable on Making Sense of the Data in Real-World Clinical Practice

BACKGROUND

For aesthetic treatment with botulinum neurotoxin type A (BoNTA), interest in maximizing treatment duration and efficacy has prompted study of doses higher than those used in registration studies. As data emerge, it is important that physicians understand how to apply study findings to their own practice so that patient demand is satisfied.

OBJECTIVES

To bring together leading experts in neuromodulators for a roundtable discussion on the implications of high-dose BoNTA studies for patient care.

METHODS

The authors reviewed and discussed recent data from high-dose BoNTA studies for abobotulinum toxin A, incobotulinum toxin A, and Oonobotulinumtoxin A.

RESULTS

Discussion focused on the challenges of data interpretation and extrapolation of study findings for real-world patient care. The authors participated in a candid discussion of whether the observed improvements in treatment duration and patient satisfaction warrant treatment with high-dose regimens delivered as high-concentration injections. Safety was also discussed, as well as economic considerations for both practices and patients. Of note, for BoNTA products, the registration dose, when administered in a smaller total volume, appears to give rise to more durable results than those observed in pivotal trials, implicating product concentration as an important consideration. Importantly, at higher doses, extended duration of effect does not appear to be at the expense of natural-looking results.

CONCLUSIONS

While the authors provide considerations for the development of individual clinical practice, there is no one-size-fits-all recommendation. It may be that "high-dose" BoNTA is in reality the optimal dose; however, important economic considerations may prevent rapid uptake for all patients.

Phase I/III Clinical Trial to Evaluate the Safety and Efficacy of a New Botulinum Toxin (HU-014) Versus OnabotulinumtoxinA in Subjects With Moderate-to-Severe Crow's Feet Lines

BACKGROUND

HU-014, a newly introduced botulinum toxin type A, has not been investigated for its efficacy and safety in crow's feet line (CFL) treatment.

OBJECTIVE

Here, we compared the efficacy and safety of HU-014 and onabotulinumtoxinA in CFL treatment.

METHODS

This was a randomized, double-blind, active drug-controlled, multicenter, 16-week, Phase I/III study designed to determine the noninferiority of HU-014 compared with onabotulinumtoxinA in moderate-to-severe CFL treatment. In the Phase III study, 290 subjects were randomized at a 1:1 ratio to receive a single treatment of HU-014 or onabotulinumtoxinA. The primary endpoint was the proportion of subjects achieving Grade 0 or 1 in the facial wrinkle scale on maximum smile at Week 4.

RESULTS

The primary endpoint was achieved by 72% of the subjects with HU-014 and onabotulinumtoxinA treatments, supporting the noninferiority of HU-014 compared with onabotulinumtoxinA. All secondary efficacy outcomes were achieved by the subjects. The 2 groups showed no significant differences in the safety analysis.

CONCLUSION

HU-014 has noninferior efficacy and safety compared with onabotulinumtoxinA in the treatment of CFL.

Influence of botulinum toxin type A esthetic injections on facial expressions

BACKGROUND

Botulinum toxin type A (BoNT-A) injection remains the leading medical cosmetic procedure worldwide, with a high rate of patient satisfaction. However, it still suffers from patients' fear of being unable to transmit their emotions and of looking frozen from unnatural results.

AIM

This study aimed to determine whether BoNT-A can decrease the intensity of emotions in facial expressions.

PATIENTS/METHODS

In this single-center prospective study, 42 patient investigators assessed four patients' facial expressions for six emotions and neutral faces, before and after injection of 36 IU or 48 IU of onabotulinumtoxinA, using photographs. Photographs were presented on a tablet to the investigators.

RESULTS

There were no statistical differences between the before and after photographs for the intensity of emotions for all expressions (P > .05) except for the expression of surprise in the group of patients that received 48 IU of the injection (protocol with injection of the frontalis muscle). All patient investigators answered negatively to the question "Do you think that this patient has a 'frozen face'?".

CONCLUSION

This study shows that esthetic injection of BoNT-A in the upper face has no negative effects on facial expressions and does not lead to the feared "frozen face" when it is injected with respect for best practice guidelines. This study can be used as an example for patients who have some reticences against BoNT-A injection.

Different injection patterns of incobotulinumtoxinA for crow's feet: a split-face comparative study

BACKGROUND

IncobotulinumtoxinA has been previously used for the treatment of lateral periorbital lines (crow's feet). However, a standardized injection technique has not been established.

OBJECTIVES

To compare the efficacy and effect duration of two injection techniques of incobotulinumtoxinA for crow's feet treatment.

METHODS

Forty-eight patients with crow's feet were recruited and randomly assigned to receive bilateral treatments using either a 3-point intramuscular or a 6-point intradermal injection technique (8-12 units of incobotulinumtoxinA on each side). Improvement was assessed at 1, 2, 4, 8, 12, 16, 20 and 24 weeks postinjection. An objective evaluation was assessed by the indentation index using a 3D camera and a subjective evaluation was assessed by a blinded dermatologist using the Flynn validated assessment scale (FVAS) for the upper face. The patients assessed the results using the Global Aesthetic Improvement Scale (GAIS). Side-effects were evaluated at each visit.

RESULTS

After treatment, a significantly greater reduction in the indentation index of periorbital wrinkles on the 3-point intramuscular injection side compared with the 6-point intradermal injection side was observed at 8, 12, and 16 weeks. The results from the FVAS and GAIS scores showed significantly longer median times to relapse of the periorbital wrinkle for the 3-point intramuscular injection compared with the 6-point intradermal injection. Pain and bruising were slightly greater with the 6-point intradermal technique.

CONCLUSIONS

This study reaffirmed the efficacy of incobotulinumtoxinA for the treatment of crow's feet. The 3-point intramuscular injection technique yielded greater efficacy and longer duration of action than the 6-point intradermal injection technique.

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

BACKGROUND

The literature on botulinum neurotoxin type A (BoNT-A) is extensive, often contradictory, and confounded by a competitive market of products and research attempting to distinguish brand individuality.

METHODS

A comprehensive review of literature on the principles of BoNT-A in aesthetics as well as clinical examples.

RESULTS

In 2017, the Eight Key Clinical Postulates were formulated as a guide for the aesthetic practitioner in understanding BoNT-A pharmacodynamics and to compare different toxins. These are now updated to include (a) All type A toxins act identically; (b) The mathematical relationship between toxin and receptor is the basis of efficacy, and clinical efficacy is influenced by molecular potency and patient attributes including muscle mass, gender, age, and ethnicity; (c) Efficacy, onset, and duration are functions of "molecular potency" defined as the number of active 150 kDa molecules available for binding; (d) "Molecular potency" is difficult to objectively quantify for commercially available toxins; (e) Up to a point, increased molecular potency decreases time to onset and increases duration of effect, and the "Molecular Potency Quotient" is a construct for comparing molecular potency commercial cost; (f) The area of effect of a toxin injection is dependent upon molecular potency, diffusion (passive), and spread (active); (g) Differing reconstitution volumes; and (h) Increased number of injection sites can affect spread, onset, and duration of effect.

CONCLUSIONS

The principles of BoNT-A use in aesthetics are complex yet understandable as outlined in the framework of the updated Eight Key Clinical Postulates and serves as a useful tool for providing the most effective treatment and interpreting research on present and future toxin formulations.

Global Trends of Botulinum Toxin Literature: A Bibliometric Analysis of Botulinum Toxin Publications Between 1975 and 2017

BACKGROUND

Botulinum toxin has been effectively used cosmetically and therapeutically for the last decades in a wide range of medical conditions. Although bibliometrics has been a popular and growing study area in recent years, medical literature lacks studies evaluating published botulinum toxin literature.

OBJECTIVE

The goal of our study was to evaluate bibliometric features and to perform a detailed trend analysis in the medical literature related to botulinum toxin.

MATERIALS AND METHODS

We analyzed all the published documents including the keywords "botulinum toxin" and "botulinum neurotoxin" and commercial brand names of botulinum toxin products between 1975 and 2017. We performed a detailed bibliometric and scientometric assessment in this field.

RESULTS

A total of 24,948 articles were retrieved from four databases provided by Web of Science, and most of which were original articles (76.19%). The United States ranked first and dominated literature with 8,729 documents (34.29%) followed by the United Kingdom, Germany, and Italy (14.61%, 11.18%, and 5.5%, respectively). The United Kingdom was detected to be the most productive country with the highest productivity (55.09) followed Switzerland, Denmark, and Germany (47.7, 34.01, and 33.98, respectively). The most studied area was neurology (56.1%) and University of California System was the most productive institution. We noted no correlation between publication number and citations by year.

CONCLUSION

We found that all top 10 authors and institutions were from developed countries. Physician from developing and the least-developed countries should be supported to carry out novel studies on botulinum toxin.

AbobotulinumtoxinA for Facial Rejuvenation: What Affects the Duration of Efficacy?

AbobotulinumtoxinA (Dysport) has a long history as a safe and effective treatment option for aesthetic rejuvenation. One of the key measures of botulinum toxin efficacy is the persistence of clinically meaningful results. The duration of efficacy depends on different factors, many of which can be controlled by the clinician to better achieve their desired results. In this review, we discuss how dose, individual patient variation, and injection technique affect the duration of botulinum toxins. Increased duration may result from increased dose or more precise placement of the toxin in the muscle. The varying anatomy and behavior of patients can affect duration as well. Measures of duration in clinical studies vary, but both a 1-grade improvement on the glabellar line severity scale and patient-reported outcomes are key measures. The clinical effects of Dysport can last up to 5 months, and patients in Dysport clinical studies remained satisfied with treatment for up to 6 months. Dysport has a legacy of safety, efficacy, and high subject satisfaction demonstrated through studies and clinical experience. Building on that legacy by correctly dosing the subject, properly accounting for the individual subject anatomy and behavior, and using specific injection techniques can help ensure that your patients have the longest lasting results.

Development of inhibition ELISA to detect antibody-induced failure of botulinum toxin a therapy in cosmetic indications

Secondary treatment failure (STF) of botulinum toxin A (BoNT/A) therapy in cosmetic indication has been postulated as production of antibody against active sites of BoNT/A in unresponsive patients. To prove of concept, detection of anti-BoNT/A antibody is required, however, current enzyme-linked immunosorbent assay (ELISA) detects human IgGs against whole BoNT/A molecule. We developed an inhibition ELISA to quantify antibodies bound to the active sites of BoNT/A using three mouse monoclonal antibodies targeting translocation domain, receptor binding site and catalytic domain of BoNT/A prior to processing ELISA to detect human IgG (hIgG) against BoNT/A. Adults naïve to BoNT/A, or treated and responsive (toxin-response), or treated but unresponsive (toxin-tolerance) were recruited. Detection of hIgG revealed that naïve volunteers had basal level of hIgG against whole BoNT/A, whereas its level was significantly lower than those hIgG in BoNT/A-exposed cohorts. Higher anti-BoNT/A levels in sera from volunteers ever-exposed to BoNT/A indicates that BoNT/A may provoke immune responses in BoNT/A-treated cohorts. Inhibition ELISA demonstrated that levels of BoNT/A-specific hIgG in tolerance patients had a dramatic decrease in mouse monoclonal antibody blockage, suggesting presence of hIgG specific to BoNT/A's three active sites in STF patients. Therefore, our ELISA detected hIgG against whole BoNT/A protein and BoNT/A active sites suggesting that human antibodies may cause STF. To compare with frontalis test, our inhibition ELISA provided good accuracy at 83.1% (50% sensitivity and 89.9% specificity). Our test may help clinicians to diagnose possibility of STF and also to monitor immune status against BoNT/A.