New trends in botulinum toxin use in dermatology

Model-based interspecies interpretation of botulinum neurotoxin type A on muscle-contraction inhibition

Botulinum neurotoxins (BoNTs) are commonly used in therapeutic and cosmetic applications. One such neurotoxin, BoNT type A (BoNT/A), has been studied widely for its effects on muscle function and contraction. Despite the importance of BoNT/A products, determining the blood concentrations of these toxins can be challenging. To address this, researchers have focused on pharmacodynamic (PD) markers, including compound muscle action potential (CMAP) and digit abduction scoring (DAS). In this study, we aimed to develop a probabilistic kinetic-pharmacodynamic (K-PD) model to interpret CMAP and DAS data obtained from mice and rats during the development of BoNT/A products. The researchers also wanted to gain a better understanding of how the estimated parameters from the model relate to the bridging of animal models to human responses. We used female Institute of Cancer Research mice and Sprague-Dawley (SD) rats to measure CMAP and DAS levels over 32 weeks after administering BoNT/A. We developed a muscle-contraction inhibition model using a virtual pharmacokinetic (PK) compartment combined with an indirect response model and performed model diagnostics using goodness-of-fit analysis, visual predictive checks (VPC), and bootstrap analysis. The CMAP and DAS profiles were dose-dependent, with recovery times varying depending on the administered dose. The final K-PD model effectively characterized the data and provided insights into species-specific differences in the PK and PD parameters. Overall, this study demonstrated the utility of PK-PD modeling in understanding the effects of BoNT/A and provides a foundation for future research on other BoNT/A products.

Botulinum toxin A dissolving microneedles for hyperhidrosis treatment: design, formulation and in vivo evaluation

Multiple periodic injections of botulinum toxin A (BTX-A) are the standard treatment of hyperhidrosis which causes excessive sweating. However, BTX-A injections can create problems, including incorrect and painful injections, the risk of drug entry into the bloodstream, the need for medical expertise, and waste disposal problems. New drug delivery systems can substantially reduce these problems. Transdermal delivery is an effective alternative to conventional BTX-A injections. However, BTX-A's large molecular size and susceptibility to degradation complicate transdermal delivery. Dissolving microneedle patches (DMNPs) encapsulated with BTX-A (BTX-A/DMNPs) are a promising solution that can penetrate the dermis painlessly and provide localized translocation of BTX-A. In this study, using high-precision 3D laser lithography and subsequent molding, DMNPs were prepared based on a combination of biocompatible polyvinylpyrrolidone and hyaluronic acid polymers to deliver BTX-A with ultra-sharp needle tips of 1.5 ± 0.5 µm. Mechanical, morphological and histological assessments of the prepared DMNPs were performed to optimize their physicochemical properties. Furthermore, the BTX-A release and diffusion kinetics across the skin layers were investigated. A COMSOL simulation was conducted to study the diffusion process. The primary stability analysis reported significant stability for three months. Finally, the functionality of the BTX-A/DMNPs for the suppression of sweat glands was confirmed on the hyperhidrosis mouse footpad, which drastically reduced sweat gland activity. The results demonstrate that these engineered DMNPs can be an effective, painless, inexpensive alternative to hypodermic injections when treating hyperhidrosis.

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.

Immunogenicity of botulinum toxin

Botulinum toxin treatment is the most common non-surgical cosmetic treatment. Although there are many available treatments using botulinum toxin, their effects are temporary and repeated injections are required. These frequent injections can trigger an immunological response. In addition, botulinum toxin acts as an antigen in the body; thus, its effect disappears progressively due to this immunological reaction, which may cause treatment failure. Active botulinum toxin consists of a core neurotoxin and complexing proteins, the exact effects of which remain unclear. However, the complexing proteins are closely related to the immune response and the formation of neutralizing antibodies. Since neutralizing antibodies can lead to treatment failure, their formation should be prevented. Furthermore, various methods of detecting neutralizing antibodies have been used to predict treatment failure.

Utilities of Botulinum Toxins in Dermatology and Cosmetology

Botulinum toxin (BoNT) is a neurotoxin produced by the Clostridium botulinum bacterium with a well-known efficacy and safety profile in the focal idiopathic hyperhidrosis treatment. BoNT comprises seven different neurotoxins; however, only toxins A and B are clinically employed. BoNT is lately practiced in off-label therapies for a variety of skin diseases. Scar prevention, hyperhidrosis, rhytides, eccrine nevus, alopecia, psoriasis, Darier disease, bullous skin disease, pompholyx and Raynaud's phenomenon are some of the novel indications for BoNT in cosmetic and notably non-cosmetic aspects of dermatology. To employ BoNT correctly in clinical practice, we must have a thorough understanding of the functional anatomy of the mimetic muscles. An intensive literature search was conducted to update all dermatology-oriented experiments and clinical trials on the described element of BoNT for this general overview of BoNT use in dermatology. This review aims to analyse the role of BoNT in dermatology and cosmetology.

Skin Quality - A Holistic 360° View: Consensus Results

Introduction

Skin quality is an important component of human attractiveness. To date, there are no standardized criteria for good skin quality. To establish a consensus for good skin quality parameters and measurement and treatment options, a virtual skin quality advisory board consisting of a global panel of highly experienced aesthetic dermatologists/aesthetic physicians was convened.

Methods

A total of 10 dermatologists/aesthetic physicians served on the advisory board. A modified version of the Delphi method was used to arrive at consensus. Members accessed an online platform to review statements on skin quality criteria from their peers, including treatment and measurement options, and voted to indicate whether they agreed or disagreed. Statements that did not have agreement were modified and the members voted again. Consensus was defined as: strong consensus = greater than 95% agreement; consensus = 75% to 95% agreement; majority consent = 50% to 75% agreement; no consensus = less than 50% agreement.

Results

There was strong consensus that good skin quality is defined as healthy, youthful in appearance (appearing younger than a person's chronological age), undamaged skin and that skin quality can be described across all ethnicities by four emergent perceptual categories (EPCs): skin tone evenness, skin surface evenness, skin firmness, and skin glow. The EPCs can be affected by multiple tissue layers (ie, skin surface quality can stem from and be impacted by deep structures or tissues). This means that topical approaches may not be sufficient. Instead, improving skin quality EPCs can require a multilayer treatment strategy.

Conclusion

This global advisory board established strong consensus that skin quality can be described by four EPCs, which can help clinicians determine the appropriate treatment option(s) and the tissue or skin layer(s) to address. Skin quality is important to human health and wellbeing and patients' perception for the need for aesthetic treatment.

A Validated Photonumeric Scale for the Evaluation of Neck Skin Laxity

BACKGROUND

Neck aging is usually evaluated together with the lower face. To date, a skin laxity scale for the neck as an independent anatomical district is lacking.

OBJECTIVE

To create and validate a proposed photonumeric neck skin laxity (NSL) scale.

MATERIALS AND METHODS

Frontal neck photographic images of 110 subjects were collected. Each standardized neck image was evaluated twice by 3 independent doctors, 1 week apart. A 4-point photonumeric NSL scale was developed (0 = absence of skin laxity and 4 = severe skin laxity) and validated in terms of intraobserver and interobserver correlation and internal consistency.

RESULTS

The intraobserver reliability analysis of the 2 assessments performed by each observer revealed excellent correlation and consistency of the severity grading, independently of the time of evaluation (from 0.96 to 0.99, p < .01). Furthermore, the interobserver reliability analysis revealed an excellent agreement between the evaluators and an internal consistency independent of the evaluator (0.97, p < .01).

CONCLUSION

The newly developed NSL scale is a reliable and reproducible scoring system for the aesthetic evaluation of skin laxity of the neck.

Botulinum Toxin: An Effective Treatment for Flushing and Persistent Erythema in Rosacea

Botulinum toxin has been used to treat persistent erythema and flushing in rosacea for several years. Here, we describe two women and one man, each with rosacea with flushing and permanent erythema refractory to conventional treatment, who achieved satisfactory and lasting results following intradermal application of botulinum toxin. Two different botulinum toxin types were used. Toxin concentrations of 3.75U per 0.1 mL (abobotulinum) and 1.25U per 0.1 mL (incobotulinum) were used for each patient were used for each patient. The outcomes were measured using polarized photography to evaluate the decrease in vascular involvement. In the three cases presented here, botulinum toxin was effective for controlling erythema and flushing associated with rosacea; we also observed a prolonged duration of these improvements without the rebound effect of topical therapies.

Efficacy of scopolamine plus propofol in the treatment of recalcitrant psoriasis: A pilot study

Accumulating evidence suggests that botulinum neurotoxins (BoNTs), which inhibit acetylcholine release, can be used for treating plaque psoriasis. The therapeutic effects of scopolamine occur through antagonism of central muscarinic acetylcholine receptors. Thus, scopolamine has potential for the treatment of psoriasis. We aimed to evaluate the efficacy and safety of scopolamine plus propofol for the treatment of recalcitrant psoriasis. Twelve patients with recalcitrant psoriasis were enrolled. Patients received intravenous injection of scopolamine plus propofol for 5 consecutive days per month for a total of 3 months. Clinical efficacy was evaluated using a Psoriasis Area and Severity Index (PASI) score. Efficacy outcome was ≥75% reduction in PASI score (PASI75) from baseline. Two patients were lost to follow-up. At week 8, two of 10 patients (20%) achieved PASI75, and at week 12, seven of 10 (70%) achieved PASI75. Treatment was well tolerated, with no reported adverse events. Our study revealed the efficacy and safety of scopolamine plus propofol for the treatment of recalcitrant psoriasis. Scopolamine plus propofol therapy may be a new treatment for recalcitrant psoriasis.

Botulinum toxin in treating Hailey-Hailey disease: A systematic review

BACKGROUND

Hailey-Hailey disease is a rare disorder characterized by recurrent painful blistering, erosions, maceration in the intertriginous regions. Botulinum toxin has been used in the treatment of Hailey-Hailey disease.

AIMS

This study aimed to examine all published articles on botulinum toxin in the treatment of Hailey-Hailey disease, and to evaluate its efficacy and safety.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were used to identify eligible articles on August 8, 2020. The searching strategy was "(Hailey Hailey or Hailey-Hailey or pemphigus) and botulinum."

RESULTS

Sixteen articles including 38 patients described the use of botulinum toxin in treating Hailey-Hailey disease. Only one case had no response, while the other patients all had partial or complete remission. No side effects were reported. Nine articles including 10 patients mainly described other treatment options, and the patients were only treated with botulinum toxin previously. Their responses to botulinum toxin were limited: one was mild improvement, one was partial response, and the other eight failed.

CONCLUSION

Botulinum toxin is not almighty, but a promising alternative option. We recommend botulinum toxin as an adjuvant or supplemental treatment modality for severe and recalcitrant Hailey-Hailey disease. Larger studies are warranted to confirm its efficacy, safety, long-term effects, and cost performance.

Comparative Pharmacodynamics Study of 3 Different Botulinum Toxin Type A Preparations in Mice

A new complexing protein-free botulinum toxin Type A (CBoNT) with the same mechanism of action as the botulinum toxin complex onabotulinumtoxinA (OBoNT) and complexing protein-free incobotulinumtoxinA (IBoNT) was recently developed.

Botulin Toxin Use in Rosacea and Facial Flushing Treatment

Botulinum toxin (BTX) is a neurotoxin derived from the Clostridium botulinum bacterium that inhibits the release of acetylcholine at the neuromuscular junction level whose effects has been used for many years to treat a variety of muscular/neuromuscular conditions and more recently also for cosmetic use.

BTX has experimented in some dermatological conditions, which include Rosacea and facial flushing treatment with good results. The complex mechanism underlying those results is not completely understood but was proposed a release inhibition of acetylcholine from peripheral autonomic nerves of the cutaneous vasodilatory system combined with the blockade substance P and calcitonin gene-related peptide (CGRP) thus modulating blood vessel dilatation.

We analysed the published data on BTX off label applications rosacea and flushing retrieved from PubMed.

Botulin Toxin Use in Scars/Keloids Treatment

Botulinum toxin (BTX) is a neurotoxin protein derived from the Clostridium botulinum bacterium that inhibits the release of acetylcholine at the neuromuscular junction level whose effects has been used for many years to treat a variety of muscular/neuromuscular conditions and more recently also for cosmetic use.

BTX has experimented in some dermatological conditions which include scar prevention and treatment with good results The complex mechanism underlying those results is not completely understood but several mechanisms were proposed release inhibition of different substances like (TGF)-β, substance P, calcitonin gene-related peptide (CGRP) and glutamate thus modulating cutaneous inflammation and wound healing.

We analysed the published data on BTX off label applications on scars and keloids retrieved from PubMed.