Using translational medicine to understand clinical differences between botulinum toxin formulations

Onabotulinum Toxin A (BoNT-A) for Drooling in Children: A Systematic Review and Meta-Analysis

INTRODUCTION

Sialorrhea, also known as drooling, hypersalivation, or ptyalism, has a significant impact on the medical and psychosocial well-being of children. Onabotulinum toxin A (BoNT-A) is the most commonly used botulinum toxin worldwide for the treatment of sialorrhea in children.

OBJECTIVES

To conduct a comprehensive systematic review and meta-analysis to assess the clinical efficacy and potential adverse effects of BoNT-A as a treatment for drooling in children.

METHODS

Cochrane, Embase, and Medline databases were systematically searched (up to May 2023). Out of 535 identified publications, 20 were found eligible for inclusion. A systematic review and meta-analysis were performed to determine the efficacy of BoNT-A treatment in children in reducing the frequency and severity of drooling.

RESULTS

Out of the 20 studies included, a meta-analysis was conducted on the complete dataset of eight studies involving 131 patients. BoNT-A was found to significantly decrease the severity of drooling in patients with sialorrhea (standardized mean difference [SMD], -2.07; 95% confidence interval [CI], -2.91 to -1.23; p < 0.0001) when compared with the conditions before injections using random-effects models. Six studies out of 20 reported dysphagia as an adverse effect after injection. Other side effects included thickness of saliva and pain at the site of injection.

CONCLUSION

BoNT-A is a clinically effective therapy that improves drooling severity in children with sialorrhea. Although there were some adverse side effects reported, they were transient and not severe. Future studies are needed to further evaluate the best techniques and to identify the ideal dosages required to achieve the optimal outcomes. Laryngoscope, 134:3012-3017, 2024.

Safety and Effectiveness of Repeated Botulinum Toxin A Intracavernosal Injections in Men with Erectile Dysfunction Unresponsive to Approved Pharmacological Treatments: Real-World Observational Data

Intracavernosal injections of botulinum toxin A (BTX/A ic) may be effective for difficult-to-treat erectile dysfunction (ED). This is a retrospective case series study of the effectiveness of repeated off-label BTX/A ic (onabotulinumtoxinA 100U, incobotulinumtoxinA 100U or abobotulinumtoxinA 500U) in men with ED and insufficient response to phosphodiesterase type 5 inhibitors (PDE5-Is) or prostaglandinE1 intracavernosal injections (PGE1 ICIs), defined as an International Index of Erectile Function-Erectile Function domain score (IIEF-EF) < 26 on treatment. Further injections were performed on patients' requests, and the files of men who underwent at least two injections were reviewed. The response to BTX/A ic was defined as the achievement of the minimally clinically important difference in IIEF-EF adjusted to the severity of ED on treatment at baseline. Out of 216 men treated with BTX/A ic and PDE5-Is or PGE1-ICIs, 92 (42.6%) requested at least a second injection. The median time since the preceding injection was 8.7 months. In total, 85, 44 and 23 men received, respectively, two, three and four BTX/A ic. The overall response rate was 77.5%: 85.7% in men with mild ED, 79% for moderate ED and 64.3% for severe ED on treatment. The response increased with repeated injections: 67.5%, 87.5% and 94.7%, respectively, after the second, third and fourth injections. Post-injection changes in IIEF-EF were similar across injections. The time from injection to request for a further injection varied little. Four men reported penile pain at the time of injection (1.5% of all injections), and one experienced a burn at the penile crus. Repeated BTX/A injections combined with PDE5-Is or PGE1-ICIs produced an effective and durable response, with acceptable safety.

Effectiveness and Safety of Intracavernosal IncobotulinumtoxinA (Xeomin®) 100 U as an Add-on Therapy to Standard Pharmacological Treatment for Difficult-to-Treat Erectile Dysfunction: A Case Series

Registered pharmacological treatments are insufficiently effective for erectile dysfunction (ED) in around 30% of affected men. Intracavernosal injection (ICI) of ona- and abobotulinumtoxinA can reduce ED in insufficient responders. We aimed to assess the safety and effectiveness of incobotulinumtoxinA ICI as an add-on therapy to phosphodiesterase-type 5 inhibitors (PDE5-Is) or prostaglandinE1 ICIs (PGE1 ICIs) to treat ED that did not respond sufficiently to this treatment alone. We retrospectively analyzed data from 66 men with difficult to treat ED treated with single or repeated incobotulinumtoxinA 100U ICI as an add-on therapy. Response rate (increase in International Index of Erectile Function-Erectile Function domain score ≥ the minimum clinically important difference) was 52% (median (1st–3rd quartile) 43.5 (34–71) days post-incobotulinumtoxinA ICI). ED etiology (except spinal cord injury) and severity did not influence effectiveness. Only a clinically significant response to the 1st injection predicted a request for a 2nd injection (OR = 5.6, 95%, CI 1.6–19.4). Three men reported mild penile pain during the injection. These results provide preliminary evidence for the effectiveness and safety of incobotulinumtoxinA ICI as an add-on therapy to treat ED that is insufficiently responsive to standard care and provides support for the multicenter randomized clinical trial NCT05196308.

Analgesic potential of different available commercial brands of botulinum neurotoxin-A in formalin-induced orofacial pain in mice

The use of botulinum neurotoxin-A (BoNT-A) is an alternative for the management of orofacial pain disorders. Although only Botox has labeled, there are other commercial brands available for use, among them: Dysport, Botulift, Prosigne, and Xeomin. The objective of the present study was to evaluate the possible differences in the antinociceptive effect evoked by different commercially available formulations of BoNT-A in an animal model of inflammatory orofacial pain induced by formalin injection. Male C57/BL6 mice (20–25 g) were submitted to the pre-treatment with five different commercial brands of BoNT-A (Botox, Botulift, Xeomin, Dysport, or Prosigne; with doses between 0.02 and 0.2 Units of Botulinum Toxin, in 20 μL of 0.9% saline) three days prior the 2% formalin injection. All injections were made subcutaneously into the right perinasal area. After formalin injections, nociceptive behaviors like rubbing the place of injection were quantified during the neurogenic (0–5 min) and inflammatory (15–30 min) phases. The treatment using Botox, Botulift, and Xeomin were able to induce antinociceptive effects in both phases of the formalin-induced pain animal model, however, Dysport and Prosigne reduced the response in neither of them. Our data suggest that the treatment using different formulations of BoNT-A is not similar in efficacy as analgesics when evaluated in formalin-induced orofacial pain in mice.

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Botulinum neurotoxin-a reduced formalin-induced orofacial pain in mice.

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There are differences in the analgesic potential of different available commercial brands of botulinum neurotoxin-A.

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Botox, Botulift, Xeomin demonstrated analgesic effect when evaluated in formalin-induced orofacial pain in mice.

Botulinum Toxin Type A for Glabellar Frown Lines: What Impact of Higher Doses on Outcomes?

Botulinum toxin serotype-A (BoNT-A) preparations are widely used to improve the appearance of wrinkles. While effective and well tolerated, patients require retreatment over time to re-establish the effects. There is growing interest from patients as to whether higher doses can prolong response without significantly increasing side effects. We reviewed the efficacy and safety evidence for high-dose BoNT-A treatment of glabellar lines, by evaluating high-dose studies published since 2015. Toxins approved for glabellar line treatment in the US or Europe were considered. "High-dose" indicated doses above the licensed dose for each BoNT-A preparation. Five studies met the inclusion criteria and most were randomized, double-blind trials; designs and population sizes varied. Findings suggested that higher-dose BoNT-A treatment is feasible and may improve response duration without increased safety issues. Around 9 months' median duration was achieved with a 2-2.5-fold increase of the abobotulinumtoxinA on-label dose, or with a 5-fold increase in incobotulinumtoxinA dose. A 2-4-fold increase of the onabotulinumtoxinA on-label dose yielded a median duration of around 6 months. Importantly, patient satisfaction and natural look remained with increasing abobotulinumtoxinA doses. While more data are needed, these findings may lead to more effective, individually tailored treatment plans to meet patient expectations.

Real-World Dosing of OnabotulinumtoxinA and IncobotulinumtoxinA for Cervical Dystonia and Blepharospasm: Results from TRUDOSE and TRUDOSE II

The real-world use of onabotulinumtoxinA and incobotulinumtoxinA for cervical dystonia and blepharospasm treatment was assessed in two separate retrospective studies using identical protocols (TRUDOSE and TRUDOSE II). The studies were conducted in Mexico, Norway, and United Kingdom and designed to evaluate dose utilization of the two botulinum toxins in clinical practice. Eighty-three patients treated with both onabotulinumtoxinA and incobotulinumtoxinA for ≥2 years for each botulinum toxin were included, (52, cervical dystonia; 31, blepharospasm). All patients switched from onabotulinumtoxinA to incobotulinumtoxinA for administrative/financial reasons. A range of dose ratios (incobotulinumtoxinA to onabotulinumtoxinA) was reported; with the majority of dose ratios being >1. The mean dose ratio was >1 regardless of the study site or underlying clinical condition. The inter-injection interval was significantly longer for onabotulinumtoxinA versus incobotulinumtoxinA when assessed for all patients (15.5 vs. 14.3 weeks; p = 0.006), resulting in fewer onabotulinumtoxinA treatments over the study time period. Consistent with product labeling, no single fixed-dose ratio exists between incobotulinumtoxinA and onabotulinumtoxinA. The dosage of each should be individualized based on patient needs and used as per product labeling. These real-world utilization data may have pharmacoeconomic implications.

Protocol for The Toxin Study: Understanding clinical and patient reported response of children and young people with cerebral palsy to intramuscular lower limb Botulinum neurotoxin-A injections, exploring all domains of the ICF. A pragmatic longitudinal observational study using a prospective one-group repeated measures design

INTRODUCTION

Botulinum neurotoxin-A (BoNT-A) is an accepted treatment modality for the management of hypertonia in children and young people with cerebral palsy (CYPwCP). Nevertheless, there are concerns about the long-term effects of BoNT-A, with a lack of consensus regarding the most meaningful outcome measures to guide its use. Most evidence to date is based on short-term outcomes, related to changes at impairment level (restrictions of body functions and structures), rather than changes in adaptive skills (enabling both activity and participation). The proposed study aims to evaluate clinical and patient reported outcomes in ambulant CYPwCP receiving lower limb BoNT-A injections over a 12-month period within all domains of the WHO's International Classification of Functioning, Disability and Health and health-related quality of life (HRQoL).

METHODS AND ANALYSIS

This pragmatic prospective longitudinal observational study will use a one-group repeated measures design. Sixty CYPwCP, classified as Gross Motor Function Classification System (GMFCS) levels I-III, aged between 4 and 18 years, will be recruited from an established movement disorder service in London, UK. Standardised clinical and patient reported outcome measures within all ICF domains; body structures and function, activity (including quality of movement), goal attainment, participation and HRQoL, will be collected preinjection and at 6 weeks, 6 months and up to 12 months postinjection. A representative subgroup of children and carers will participate in a qualitative component of the study, exploring how their experience of BoNT-A treatment relates to clinical outcome measures.

ETHICS AND DISSEMINATION

Central London Research Ethics Committee has granted ethics approval (#IRAS 211617 #REC 17/LO/0579). Findings will be disseminated in peer-reviewed publications, conferences and via networks to participants and relevant stakeholders using a variety of accessible formats including social media.

Do complexing proteins provide mechanical protection for botulinum neurotoxins?

Botulinum toxin (BT) consists of botulinum neurotoxin and complexing proteins (CPs). CPs might provide mechanical protection for botulinum neurotoxin. As incobotulinumtoxinA (INCO, Xeomin®) does not contain CPs, we wanted to compare its mechanical stability to that of onabotulinumtoxinA (ONA, Botox®) containing CPs. For this, ONA and INCO were reconstituted without mechanical stress (NS) and with mechanical stress (WS) generated by a recently introduced stress test. Potencies were then measured by the paralysis times (PTs) in the mouse diaphragm assay. ONA-PT was 75.8 ± 10.3 min (n = 6) under NS and 116.7 ± 29.8 min (n = 6) under WS (two-tailed t test, p = 0.002). Mechanical stress increased the ONA-PT by 35.0% on the Growth Percentage Index. INCO-PT was 66.0 ± 7.0 min for NS and 76.0 ± 1.0 min for WS (t test, p = 0.129). Mechanical stress increased the INCO-PT by 13.2% on the Growth Percentage Index. Our data show that mechanical stress inactivates a CP-containing BT drug, but not a CP-free BT drug. We conclude that CPs do not provide protection against mechanical stress, supporting the view that CPs are not necessary for therapeutic purposes.

AbobotulinumtoxinA for the treatment of overactive bladder

INTRODUCTION

Overactive bladder is a common condition that can have a negative impact on quality of life. Botulinum Toxin A is a third line treatment for overactive bladder following conservative measures and anticholinergic medication. At present, OnabotulinumtoxinA is the only preparation licensed for this indication. More recently, trials have been undertaken to compare the efficacy of this to AbobotulinumtoxinA. Areas covered: This article aims to provide an overview of AbobotulinumtoxinA, which is currently not yet licensed for overactive bladder or neurogenic detrusor overactivity. It will detail the pharmacokinetics and dynamics, assess the available clinical trial data and make comparisons with current clinical practice. A systematic literature search was completed, using ovid Medline and Embase, with the aim to review all data concerning the administration of AbobotulinumtoxinA for the treatment of overactive bladder. Expert opinion: Currently, there are a lack of data on the use of AbobotulinumtoxinA for overactive bladder or neurogenic detrusor overactivity. Current evidence concentrates on its use in neurogenic detrusor overactivity, and there are data to show it may be as efficacious as OnabotulinumtoxinA. However, there is a lack of homogenous data to compare the two products and therefore we are unable to recommend this currently.

Botulinum neurotoxin formulations: overcoming the confusion

Botulinum toxin A is produced by anaerobic spore-forming bacteria and is used for various therapeutic and cosmetic purposes. Botulinum toxin A injections are the most popular nonsurgical procedure worldwide. Despite an increased demand for botulinum toxin A injections, the clinical pharmacology and differences in formulation of commonly available products are poorly understood. The various products available in the market are unique and vary in terms of units, chemical properties, biological activities, and weight, and are therefore not interchangeable. For safe clinical practice and to achieve optimal results, the practitioners need to understand the clinical issues of potency, conversion ratio, and safety issues (toxin spread and immunogenicity). In this paper, the basic clinical pharmacology of botulinum toxin A and differences between onabotulinum toxin A, abobotulinum toxin A, and incobotulinum toxin A are discussed.

Botulinum Toxin in Aesthetic Medicine: Myths and Realities

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.

Chemodenervation for the Treatment of Facial Dystonia: A Report by the American Academy of Ophthalmology

PURPOSE

To review the medical literature on the outcomes and complications of various Food and Drug Administration-approved botulinum toxins for benign essential blepharospasm (BEB) and hemifacial spasm (HFS).

METHODS

Literature searches were last conducted in February 2017 in PubMed for articles published in English and in the Cochrane Library database without language limitations; studies published before 2000 were excluded. The combined searches yielded 127 citations. Of these, 13 articles were deemed appropriate for inclusion in this assessment, and the panel methodologist assigned ratings to them according to the level of evidence.

RESULTS

A combined total of 1523 patients (1143 with BEB and 380 with HFS) were included in the 13 studies. Five studies provided level I evidence, 2 studies provided level II evidence, and 6 studies provided level III evidence. Pretarsal injections were more efficacious than preseptal injections (96% vs. 86%, respectively). Pretarsal injections also resulted in a higher response rate on clinical scales (P < 0.05) and a longer duration of maximum response for both HFS and BEB. Patients with HFS require lower overall doses of onabotulinumtoxinA than patients with BEB for a similar duration of effect. Adverse events were dose related, and they occurred more frequently in patients who were given more units.

CONCLUSIONS

Level I evidence supports the efficacy of Botox (Allergan Corp., Irvine, CA), Meditoxin, and Xeomin (Merz Pharmaceuticals, Frankfurt am Main, Germany) for the treatment of BEB. Meditoxin and Botox have equivalent effectiveness and incidence of adverse events for BEB and HFS. Dysport (Ipsen Biopharmaceuticals, Inc, Paris, France) seems to have efficacy similar to Botox and Meditoxin for BEB and HFS, but any definitive conclusions from the 2 level II studies in this review are limited by differences in the methodologies used. Higher doses of Botox and Dysport result in more adverse events. Repeated treatments using Botox seem to maintain efficacy for treatment of facial dystonias over a follow-up period of at least 10 years, based on level III evidence.

Switch to Abobotulinum toxin A may be useful in the treatment of neurogenic detrusor overactivity when intradetrusor injections of Onabotulinum toxin A failed

AIMS

To assess the outcomes of switching to a different brand of botulinum toxin A (BTA, from Botox® to Dysport®) in case of failure of intradetrusor injections (IDI) of Botox® in the treatment of neurogenic detrusor overactivity (NDO).

METHODS

The charts of all patients who underwent a switch to IDI of Dysport® after failure of an IDI of Botox® at six departments of neurourology were retrospectively reviewed. The main outcomes of interest were the bladder diary data and four urodynamic parameters: maximum cystometric capacity (MCC), maximum detrusor pressure (PDET max), and volume at first uninhibited detrusor contraction (UDC).

RESULTS

Fifty-seven patients were included. After the first injection of Dysport®, no adverse events were reported. A significant decrease in number of urinary incontinence episodes per day was observed in 52.63% of patients (P < 0.001) and all patients experienced a reduction in PDET Max (-8.1 cmH20 on average; P = 0.003). MCC significantly increased by a mean of 41.2 (P = 0.02). The proportion of patients with no UDC increased significantly at week 6 after ATA injections (from 15.79% to 43.9%; P = 0.0002). Hence, 32 patients draw clinical and/or urodynamic benefits from the botulinum toxin switch from (56.14%). After a median follow up of 21 months, 87% of responders to BTA switch were still treated successfully with BTA.

CONCLUSION

Most patients refractory to Botox® (56.14%) draw benefits from the switch to Dysport®.

Conversion Ratio between Botox®, Dysport®, and Xeomin® in Clinical Practice

Botulinum neurotoxin has revolutionized the treatment of spasticity and is now administered worldwide. There are currently three leading botulinum neurotoxin type A products available in the Western Hemisphere: onabotulinum toxin-A (ONA) Botox(®), abobotulinum toxin-A (ABO), Dysport(®), and incobotulinum toxin A (INCO, Xeomin(®)). Although the efficacies are similar, there is an intense debate regarding the comparability of various preparations. Here we will address the clinical issues of potency and conversion ratios, as well as safety issues such as toxin spread and immunogenicity, to provide guidance for BoNT-A use in clinical practice. INCO was shown to be as effective as ONA with a comparable adverse event profile when a clinical conversion ratio of 1:1 was used. The available clinical and preclinical data suggest that a conversion ratio ABO:ONA of 3:1-or even lower-could be appropriate for treating spasticity, cervical dystonia, and blepharospasm or hemifacial spasm. A higher conversion ratio may lead to an overdosing of ABO. While uncommon, distant spread may occur; however, several factors other than the pharmaceutical preparation are thought to affect spread. Finally, whereas the three products have similar efficacy when properly dosed, ABO has a better cost-efficacy profile.

Pharmaceutical, biological, and clinical properties of botulinum neurotoxin type A products

Botulinum neurotoxin injections are a valuable treatment modality for many therapeutic indications and have revolutionized the field of aesthetic medicine so that they are the leading cosmetic procedure performed worldwide. Studies show that onabotulinumtoxinA, abobotulinumtoxinA, and incobotulinumtoxinA are comparable in terms of clinical efficacy. Differences between the products relate to the botulinum neurotoxin complexes, specific biological potency, and their immunogenicity. Protein complex size and molecular weight have no effect on biological activity, stability, distribution, or side effect profile. Complexing proteins and inactive toxin (toxoid) content increase the risk of neutralizing antibody formation, which can cause secondary treatment failure, particularly in chronic disorders that require frequent injections and long-term treatment. These attributes could lead to differences in therapeutic outcomes, and, given the widespread aesthetic use of these three neurotoxin products, physicians should be aware of how they differ to ensure their safe and effective use.

Clinical differences between botulinum neurotoxin type A and B

In humans, the therapeutic use of botulinum neurotoxin A (BoNT/A) is well recognized and continuously expanding. Four BoNTs are widely available for clinical practice: three are serotype A and one is serotype B: onabotulinumtoxinA (A/Ona), abobotulinumtoxinA (A/Abo) and incobotulinumtoxinA (A/Inco), rimabotulinumtoxinB (B/Rima). A/Abo, A/Inco, A/Ona and B/Rima are all licensed worldwide for cervical dystonia. In addition, the three BoNT/A products are approved for blepharospasm and focal dystonias, spasticity, hemifacial spasm, hyperhidrosis and facial lines, with remarkable regional differences. These toxin brands differ for specific activity, packaging, constituents, excipient, and storage. Comparative literature assessing the relative safety and efficacy of different BoNT products is limited, most data come from reports on small samples, and only a few studies meet criteria of evidence-based medicine. One study compared the effects of BoNT/A and BoNT/B on muscle activity of healthy volunteers, showing similar neurophysiological effects with a dose ratio of 1:100. In cervical dystonia, when comparing the effects of BoNT/A and BoNT/B, results are more variable, some studies reporting roughly similar peak effect and overall duration (at a ratio of 1:66, others reporting substantially shorter duration of BoNT/B than BoNT/A (at a ratio 1/24). Although the results of clinical studies are difficult to compare for methodological differences (dose ratio, study design, outcome measures), it is widely accepted that: BoNT/B is clinically effective using appropriate doses as BoNT/A (1:40-50), injections are generally more painful, in most of the studies on muscular conditions, efficacy is shorter, and immunogenicity higher. Since the earliest clinical trials, it has been reported that autonomic side effects are more frequent after BoNT/B injections, and this observation encouraged the use of BoNT/B for sialorrhea, hyperhidrosis and other non-motor symptoms. In these indications the efficacy of toxins A and B are comparable and dose ratio is 1:25-30.

Botulinum toxin type A products are not interchangeable: a review of the evidence

Botulinum toxin type A (BoNTA) products are injectable biologic medications derived from Clostridium botulinum bacteria. Several different BoNTA products are marketed in various countries, and they are not interchangeable. Differences between products include manufacturing processes, formulations, and the assay methods used to determine units of biological activity. These differences result in a specific set of interactions between each BoNTA product and the tissue injected. Consequently, the products show differences in their in vivo profiles, including preclinical dose response curves and clinical dosing, efficacy, duration, and safety/adverse events. Most, but not all, published studies document these differences, suggesting that individual BoNTA products act differently depending on experimental and clinical conditions, and these differences may not always be predictable. Differentiation through regulatory approvals provides a measure of confidence in safety and efficacy at the specified doses for each approved indication. Moreover, the products differ in the amount of study to which they have been subjected, as evidenced by the number of publications in the peer-reviewed literature and the quantity and quality of clinical studies. Given that BoNTAs are potent biological products that meet important clinical needs, it is critical to recognize that their dosing and product performance are not interchangeable and each product should be used according to manufacturer guidelines.

Change of distribution and timing of bite force after botulinum toxin type A injection evaluated by a computerized occlusion analysis system

PURPOSE

The aim of this study was to determine the force distribution and pattern of mastication after injection of botulinum toxin type A (BTX-A) into both masseter muscles. The hypothesis to be tested was that the difference between right and left balance of occlusal force diminishes over time following BTX-A injection.

MATERIALS AND METHODS

Fifteen patients were submitted to BTX-A injection therapy for subjective masseter hypertrophy. A total of 25 U of BTX-A (50 U in total) was injected into two points located 1 cm apart at the center of the lower one-third of both masseter muscles. All patients were examined using the T-Scan occlusion analysis system before and 4, 8, 12, and 24 weeks after BTX-A injection.

RESULTS

A significant change in force balance was found between the right and left sides over time and the difference between the two sides decreased with the time post-injection, reaching a minimum at 12 weeks. Comparison of the force balance between the anterior and posterior occlusions revealed no significant difference at any of the time points. The occlusion and disclusion times (right and left sides) did not differ significantly with time since BTX-A injection.

CONCLUSION

A decline in the difference in the clenching force between the left and right sides was found with increasing time up to 12 weeks following BTX-A injection.

Botulinum toxin A treatment of the lower extremities in children with cerebral palsy

OBJECTIVES

In the last 2 decades, BTX-A is increasingly being used in the management of spasticity in children with Cerebral Palsy (CP) and there is no doubt about its effect on range of motion, spasticity reduction and gait pattern in this patient population. However, in daily practice, there is still an ongoing search for the best way to apply BTX-A. Two studies were set up to evaluate how successful an integrated multilevel treatment approach is in children with CP. The first study identifies crucial factors within the treatment strategy which may predict the outcome. The second study evaluates the efficacy of repeated BTX-A injections.

METHODS

Patient selection was based on following criteria: diagnosis of CP, lower limb BTX-A treatment, age at time of treatment <24 years, no combined surgery at the time of BTX-A injections, 3D gait analysis and clinical evaluation pre and 2 months post BTX-A injections. The first study included the last treatment of 577 patients. In the second study, the first and last BTX-A treatment of 222 children were included. The Goal Attainment Scale (GAS) was used to evaluate the functional outcome of each treatment session.

RESULTS

In the first study, the mean GAS score of the total group was 51.7 (±7.5). Considering a converted total score of 50 as cut-off score for successful treatment, 67.1 % of the treatments were successful. Significantly higher GAS scores were found in mildly involved children compared to more involved children (p < 0.0001) and for multilevel injections or injections in the distal muscle groups only compared to injections in the proximal muscles of the lower limb only (p < 0.0001). Other crucial factors for a successful outcome were amount of physical therapy per week (p=0.0026), post injection casting (p=0.005) and frequency of using day and night orthoses after injection (p < 0.0001). In the second study, the mean GAS score of the total group decreased from 54.8 (±6.8) at the first treatment to 50.7 (±6.9) at the last treatment, indicating that on average, repeated BTX-A treatment is successful.

CONCLUSION

The integrated multilevel BTX-A approach is successful in children with CP. Several factors might help the clinician to select patients that are most likely to benefit from the treatment, to assure the most optimal treatment strategy and to predict the outcome. Each treatment should be carefully planned and goals should be well chosen, because the effectiveness of the BTX-A treatment may decrease with increasing number of treatments in the same patient.

Efficacy and safety of incobotulinum toxin A in periocular rhytides and masseteric hypertrophy: side-by-side comparison with onabotulinum toxin A

BACKGROUND

Incobotulinum is a newly developed botulinum toxin A in which the complexing proteins had been removed.

OBJECTIVE

The aim was to compare the efficacy and safety of incobotulinum with onabotulinum in treating periocular rhytides and masseteric hypertrophy.

METHODS

A randomized, double-blind, split-face study was planned. Fifty-six patients were treated for periocular rhytides and the other 56 patients were treated for masseteric hypertrophy. Onabotulinum was injected on one side of the face and incobotulinum was injected on the other side of the face. The degree of periocular rhytides and masseteric hypertrophy was rated using Fitzpatrick Wrinkle Classification System (FWCS) and 10-point visual analogue scale (VAS) (0: the minimum to 10: the maximum). Objective and subjective rating was performed at pretreatment and every posttreatment follow-up visit by investigators and subjects.

RESULT

The efficacy and safety of incobotulinum were not inferior to those of onabotulinum in treating periocular rhytides and masseteric hypertrophy up to 16 weeks after injection. There were no noteworthy differences in the onset time of effect between two botulinum toxins for periocular wrinkles and masseteric hypertrophy. No adverse event was reported.

CONCLUSION

Incobotulinum provided non-inferior efficacy and safety for the treatment of periocular rhytides and masseteric hypertrophy compared with classic onabotulinum.

A pharmacodynamic comparison study of different botulinum toxin type A preparations

BACKGROUND

Because more botulinum toxin (BoNT) preparations have become available worldwide, there is a clinical need to compare the pharmacologic profiles of these products.

OBJECTIVE

We compared three different preparations: onabotulinumtoxinA (ona-BoNT/A), abobotulinumtoxinA (abo-BoNT/A), and Neuronox (neu-BoNT/A), in a mouse model using a digit abduction scoring (DAS) assay.

METHODS

The efficacy, duration of effect, and safety margin of each preparation was determined after delivering a single injection to the right gastrocnemius (0-240 U/kg body weight of neu-BoNT/A or ona-BoNT/A; 0-600 Speywood Units/kg body weight of abo-BoNT/A).

RESULTS

Neu-BoNT/A (intramuscular (IM) median effective dose (ED(50) ) 11.2 ± 2.7 U/kg) and ona-BoNT/A (IM ED(50) 11.9 ± 2.4 U/kg) had similar effects in terms of muscle weakness at significantly lower doses than abo-BoNT/A (IM ED(50) 41.2 ± 2.4 U/kg; p < .001). The safety margin (ratio between IM ED(50) and IM median lethal dose (LD(50) )) of neu-BoNT/A (10.7 ± 2.6 U/kg) was also similar to that of ona-BoNT/A (10.3 ± 1.3 U/kg) but significantly higher than that of abo-BoNT/A (5.9 ± 0.4 U/kg; p < .02). Neu-BoNT/A and ona-BoNT/A also produced comparable patterns of DAS response and body weight recovery by day 29.

CONCLUSION

Neu-BoNT/A and ona-BoNT/A may be interchangeable based on a simple dose ratio.

IncobotulinumtoxinA (Xeomin): background, mechanism of action, and manufacturing

IncobotulinumtoxinA is the third botulinum neurotoxin type A (BoNTA) to be approved for aesthetic use in the United States. This article introduces the new product with an overview of clinical applications and a discussion of the neurotoxin's molecular structure. The role and clinical relevance of complexing proteins in BoNTA products are discussed. Finally, incobotulinumtoxinA's mechanism of action is described.

A randomised, double-blind comparison of 20 units of onabotulinumtoxinA with 30 units of incobotulinumtoxinA for glabellar lines

BACKGROUND

Biological activity data indicate that the units of incobotulinumtoxinA are not equivalent to those of onabotulinumtoxinA.

OBJECTIVE

This study compared 20 units of onabotulinumtoxinA with 30 units of incobotulinumtoxinA in the treatment of glabellar lines.

METHODS AND MATERIALS

In this multicenter, randomised, double-blind study, subjects with moderate or severe glabellar lines received a single treatment with 20 units of onabotulinumtoxinA (n = 112), or 30 units of incobotulinumtoxinA (n = 112). The primary endpoint was the percentage of subjects with a reduction of ≥ 1 point on the Facial Wrinkle Scale at maximum contraction as rated by injectors on day 28 post injection. The same variable was evaluated on days 84, 98, and 112.

RESULTS

At the primary endpoint, 20 units of onabotulinumtoxinA was as effective as 30 units of incobotulinumtoxinA (96% vs. 95% responders, respectively; difference in proportion of responders = 0.02, 95% confidence interval [CI] - 0.04, 0.07). At subsequent time points, a trend towards a higher percentage of responders was observed in the group treated with 20 units of onabotulinumtoxinA. Given that the 95% CI surpassed the upper equivalence margin at these time points, equivalence was not established.

CONCLUSION

These data support the non-interchangeability of units of onabotulinumtoxinA and incobotulinumtoxinA, and the absence of a fixed dose ratio in clinical practice.

The use of botulinum toxin and epidural analgesia for the treatment of spasticity and pain in a patient with maple syrup urine disease

A 7-year-old boy, weighing 18 kg, was diagnosed with maple syrup urine disease (MSUD). He suffered from spasticity of the lower limbs and pain that did not respond to oral medications. Injections of botulinum toxin A (BTX-A) at 10 sites and epidural analgesia with 0.125% bupivacaine were used to treat spasticity with good results. We conclude that BTX-A combined with epidural analgesia may be a useful treatment option for incapacitating, painful spasticity related to MSUD. This treatment modality allowed a comprehensive rehabilitation program to be completed and it lasted longer than 9 months.

Compositional differences among commercially available botulinum toxin type A

PURPOSE OF REVIEW

Since the advent of botulinum neurotoxin (BoNT) in the facial cosmetic field, it has become the leading nonsurgical cosmetic procedure in the USA, and several different formulations are currently in use. The aim of this study is to review the major 'players' in order to help the physician understand the clinically relevant dissimilarities between the products and by that promote treatment efficacy and patient satisfaction.

RECENT FINDINGS

The different available formulations can be classified into two groups by the existence of absence of complexing proteins. Most of the influence that was previously attributed to these proteins has been found to be less relevant clinically, the immune response being the only remaining issue with supporting evidence in the literature.

SUMMARY

Botulinum toxin type A is widely utilized in the cosmetic field, and it seems that all available and approved formulations are both well tolerated and effective in treating facial rhytids. The treating physician must be familiar with the differences between all the products, especially the fact that they are not interchangeable in respect to their recommended dosage.

A new treatment for focal dystonias: incobotulinumtoxinA (Xeomin®), a botulinum neurotoxin type A free from complexing proteins

Dystonia is a movement disorder of uncertain pathogenesis that is characterized by involuntary and inappropriate muscle contractions which cause sustained abnormal postures and movements of multiple or single (focal) body regions. The most common focal dystonias are cervical dystonia (CD) and blepharospasm (BSP). The first-line recommended treatment for CD and BSP is injection with botulinum toxin (BoNT), of which two serotypes are available: BoNT type A (BoNT/A) and BoNT type B (BoNT/B). Conventional BoNT formulations include inactive complexing proteins, which may increase the risk for antigenicity, possibly leading to treatment failure. IncobotulinumtoxinA (Xeomin(®); Merz Pharmaceuticals GmbH, Frankfurt, Germany) is a BoNT/A agent that has been recently Food and Drug Administration-approved for the treatment of adults with CD and adults with BSP previously treated with onabotulinumtoxinA (Botox(®); Allergen, Inc, Irvine, CA) - a conventional BoNT/A. IncobotulinumtoxinA is the only BoNT product that is free of complexing proteins. The necessity of complexing proteins for the effectiveness of botulinum toxin treatment has been challenged by preclinical and clinical studies with incobotulinumtoxinA. These studies have also suggested that incobotulinumtoxinA is associated with a lower risk for stimulating antibody formation than onabotulinumtoxinA. In phase 3 noninferiority trials, incobotulinumtoxinA demonstrated significant improvements in CD and BSP symptoms in both primary and secondary measures, compared with baseline, and met criteria for noninferiority versus onabotulinumtoxinA. In placebo-controlled trials, incobotulinumtoxinA also significantly improved the symptoms of CD and BSP, with robust outcomes in both primary and secondary measures. The use of incobotulinumtoxinA has been well tolerated in all trials, with an adverse event profile similar to that of onabotulinumtoxinA. Based on these data, incobotulinumtoxinA is a safe and effective BoNT/A for the treatment of CD and BSP, and may pose a lower risk for immunogenicity leading to treatment failure compared with other available BoNT agents. This paper reviews the treatment of focal dystonias with BoNTs, in particular, incobotulinumtoxinA. Controlled trials from the existing incobotulinumtoxinA literature are summarized.

Lower-face and neck antiaging treatment and prevention using onabotulinumtoxin A: the 2010 multidisciplinary French consensus--part 2

BACKGROUND

Onabotulinumtoxin A has been used for many years in the aging face treatment. A survey was organized to identify current practices in France.

OBJECTIVE

To develop consensual recommendations for treating aging lower face and neck with onabotulinumtoxin A.

METHODS AND MATERIALS

Fifty-seven participants to six regional surveys reviewed practices and techniques for each individual treatment indication. From conference summaries and data from a questionnaire, consensual recommendations were developed.

RESULTS

General considerations, key treatment rules, injection specifics (dose, site, and techniques), associated procedures/treatments, and procedure follow-up were defined by indication, i.e., nasolabial angle, nasal tip repositioning, dilated nostrils, lips and perioral area, Marionette lines and depressor anguli oris, gingival smile, risorius and zygomatic perioral muscles, masseters, chin, and platysma. For the consensus participants, current onabotulinumtoxin A use is a global preventive and corrective treatment. Overall, judicious treatment of multiple sites and adjunctive modalities, such as fillers, peels, and laser, leads to satisfactory results with a youthful, harmonious, animated, and natural-looking face.

CONCLUSION

Years of experience using onabotulinumtoxin A result in sophisticated treatment approaches, more specific targeted injections, and better understanding of lower facial and neck aging, leading to satisfying therapeutic results for patients and clinicians.

Retrospective evaluation of the dose equivalence of Botox(®) and Dysport (®) in the management of blepharospasm and hemifacial spasm: a novel paradigm for a never ending story

Botox(®) and Dysport(®) are the preparations of botulinum neurotoxin most widely used for therapeutic purposes. Several studies have addressed the topic of the equivalency ratio (D/B ratio) to be used in clinical practice and whether a reliable value exists is still a matter of debate. To this purpose, we ideated a novel paradigm by retrospectively examining the patients affected by hemifacial spasm and blepharospasm. We compared the pairs of treatments with a switch from one brand to the other undergone by the same patient in consecutive sessions with overlapping clinical outcome. Out of 2006 treatments, we found 51 treatment pairs. D/B ratio was extremely variable (range 1.2-13.3) and in most cases (65%) it was between 1:3 and 1:5. In conclusion, even if the 1:4 ratio might be reliable for clinical purpose, a true bioequivalence between Dysport(®) and Botox(®) might not exist due to the intrinsic difference in their pharmacokinetic properties.

Profile of Xeomin® (incobotulinumtoxinA) for the treatment of blepharospasm

Even though conventional botulinum neurotoxin (BoNT) products have shown successful treatment results in patients with benign blepharospasm (BEB), the main, potential long-term side effect of BoNT use is the development of immunologic resistance due to the production of neutralizing antibody to the neurotoxin after repeated injections. Xeomin^® (incobotulinumtoxinA), a unique botulinum neurotoxin type A (BoNT/A) drug free of complexing proteins otherwise contained in all conventional BoNT/A drugs, was recently approved by US Food and Drug Administration for the treatment of cervical dystonia or blepharospasm in adults. The newly approved BoNT/A drug may overcome this limitation of previous conventional products, since it contains pure neurotoxin (150 kDa) through a manufacturing process that separates it from complexing proteins such as hemagglutinins produced by fermentation of Clostridium botulinum. Many studies have also shown that Xeomin^® has the same efficacy and safety profile as complexing protein-containing products such as Botox^® and is exchangeable with Botox^® using a simple 1:1 conversion ratio. Xeomin^® represents a new treatment option for the repeated treatment of patients with blepharospasm in that it may reduce antibody-induced therapy failure. But, long-term comparative trials in naïve patients between Xeomin^® and conventional BoNT/A drugs are required to confirm the low immunogenicity of Xeomin^®.

Complexing proteins in botulinum toxin type A drugs: a help or a hindrance?

Botulinum toxin type A is a high molecular weight protein complex containing active neurotoxin and complexing proteins, the latter of which, it is believed, protect the neurotoxin when in the gastrointestinal tract, and may facilitate its absorption. Comparisons of conventional botulinum toxin type A drugs that include complexing proteins with the complexing protein-free formulation of Xeomin^® strongly suggest that complexing proteins do not affect diffusion of the active neurotoxin. Studies of Xeomin have also shown that complexing proteins do not enhance product stability in storage. However, complexing proteins may stimulate antibody development against botulinum toxin type A. Numerous observational studies have been published showing that some patients receiving conventional botulinum toxin may develop neutralizing antibodies, leading to antibody-induced therapy failure. Studies have shown that Xeomin is not associated with the development of neutralizing antibodies in animal models or in patients. In conclusion, complexing proteins do not contribute to the stability of botulinum toxin type A drugs and do not contribute to their therapeutic effects, but may be associated with a secondary nonresponse due to the development of neutralizing antibodies.

The use of botulinum toxin A in children with cerebral palsy, with a focus on the lower limb

PURPOSE

The purpose of this review is to clarify the role of botulinum toxin serotype A (BTX-A) in the treatment of children with cerebral palsy (CP), with a special focus on the lower limb.

BACKGROUND

The treatment of spasticity is central in the clinical management of children with CP. BTX-A blocks the release of acetylcholine at the motor end plate, causing a temporary muscular denervation and, in an indirect way, a reduced spasticity. Children with increased tone develop secondary problems over time, such as muscle contractures and bony deformities, which impair their function and which need orthopaedic surgery. However in these younger children, delaying surgery is crucial because the results of early surgical interventions are less predictable and have a higher risk of failure and relapse. As BTX-A treatment reduces tone in a selective way, it allows a better motor control and muscle balance across joints, resulting in an improved range of motion and potential to strengthen antagonist muscles, when started at a young age. The effects are even more obvious when the correct BTX-A application is combined with other conservative therapies, such as physiotherapy, orthotic management and casts. There is now clear evidence that the consequences of persistent increased muscle tone can be limited by applying an integrated multi-level BTX-A treatment approach. Nevertheless, important challenges such as patient selection, defining appropriate individual goals, timing, dosing and dilution, accuracy of injection technique and how to measure outcomes will be questioned. Therefore, "reflection is more important than injection" remains an actual statement.

Botulinum toxin: examining duration of effect in facial aesthetic applications

Patient satisfaction with botulinum toxin treatment is a key success factor in aesthetic procedures and is governed by the interaction of numerous variables. Duration of effect is important because it influences retreatment intervals as well as affecting cost and convenience to the patient. In order to review the evidence on the duration of benefit associated with various commercial formulations of botulinum toxin, MEDLINE was searched using the following terms: 'botulinum' and 'duration'/'retreatment' (limits: 'clinical trials,' 'meta-analyses,' 'English'). I also searched my existing reference files, reference lists of identified articles, and meeting/conference abstracts to ensure completeness. The focus was on clinical medicine and aesthetic trials. To be eligible for the analysis, studies had to include efficacy assessments at multiple timepoints. To estimate duration of benefit, the following outcomes were examined and summarized: responder rates, mean wrinkle severity scores at various timepoints (with or without changes from baseline), and relapse rates. Duration at both repose and maximum attempted muscle contraction was considered when provided. Where possible, duration was assessed by formulation and dose. The initial search yielded 164 articles. Of these, 35 included an adequate measure of duration in aesthetic indications. The majority of these (22) were on the glabellar area. Study designs and endpoints were highly heterogeneous, and duration of effect varied between studies. Several studies with the BOTOX Cosmetic (onabotulinumtoxinA; Allergan, Inc., Irvine, CA, USA) formulation of botulinum toxin type A (BoNTA) included relapse rates, defined conservatively as return to baseline levels of line severity for two consecutive visits approximately 30 days apart (at repose and maximum contraction). In these studies, duration of effect ranged from 3 to 5 months in female patients and from 4 to 6 months in male patients. Individual patients had longer durations of response. Across all studies providing relapse rates, most patients relapsed by 6 months. In studies assessing patient satisfaction, satisfaction remained high throughout the duration of the studies ( approximately 4 months). With the Dysport formulation (abobotulinumtoxinA, clostridium botulinum type A toxin-hemagglutinin complex; Ipsen Biopharm Ltd, Wrexham, England), retreatment intervals were estimated at a mean of 3.9 months (median = 3.3 months). These results were consistent with responder rates from another Dysport study in which the active treatment differed from placebo at 3 but not 4 months. A single comparative study demonstrated that the proportion of patients relapsing at week 16 was 23% (95% CI 11.5, 41.6) in the BOTOX Cosmetic group as compared with 40% (95% CI 25.2, 60.1) in the Dysport group. Myobloc (rimabotulinumtoxinB, botulinum toxin type B; Solstice Neurosciences, Inc., South San Francisco, CA, USA) was associated with shorter durations of action (2-3 months). Data from facial areas other than the glabella, although more limited, supported a duration of at least 3-4 months. The addition of BoNTA to dermal fillers or light/laser therapy appeared to increase the degree of effect. Repeated BoNTA treatments may prolong duration of effect or potentiate the effect. In conclusion, patients can expect treatments to last > or =3 months but often as many as 4-5 months depending on the facial area, dose, and formulation. Additional research should help clarify the impact of age, baseline rhytid severity, patient sex, repeated treatments, and combination treatment on longevity of effect.

Assay of diffusion of different botulinum neurotoxin type a formulations injected in the mouse leg

Botulinum neurotoxin type-A (BoNT/A) is very effective in the therapy of a wide range of human syndromes characterized by hyperactivity of peripheral cholinergic nerve terminals. Little diffusion of this toxin from the site of injection is commonly observed, but even minor changes in this property would greatly affect the validity of the treatment. Different pharmacological formulations of BoNT/A are available, and they may have different diffusion characteristics due to protein complex size, product format, and pharmacological properties. Here we assessed the extent of diffusion of three commercial preparations of BoNT/A: Botox (Allergan), Dysport (Ipsen), and Xeomin (Merz Pharmaceuticals) using a novel and highly sensitive test based on neural cell adhesion molecule (N-CAM) expression in muscle. N-CAM is a membrane glycoprotein that accumulates on muscle fibers after denervation and is not expressed in untreated adult muscle. This allows fine monitoring of the functional diffusion of this toxin, and the sensitivity of this assay is emphasized by the use of the mouse model because of the small muscle dimensions. The results presented here indicate that there is no significant difference between Botox, Dysport, and Xeomin with respect to diffusion into adjacent muscles in the mouse leg.

Undesirable distant effects following botulinum toxin type a injection

OBJECTIVES

To study the incidence of clinical signs linked to botulinum toxin type A (BoNTA) spread from the injection site.

METHODS

Single-center, retrospective, cohort study. All patients who received BoNTA injections for spasticity treatment were assessed 1 month postinjection. Adverse effects indicative of BoNTA treatment were systematically sought. Any patient with adverse effects possibly due to BoNTA spread underwent further clinical examination and single-fiber electromyography. One patient underwent neuromuscular biopsy.

RESULTS

Between January and September 2005, 266 BoNTA injection sessions (187 patients) were performed (233 BOTOX, 33 Dysport). Five patients presented with clinical signs of toxin spread. Four of these underwent single-fiber electromyography, which showed increased jitter. Neuromuscular biopsy detected signs of recent denervation without signs of reinnervation.

CONCLUSIONS

Diffusion diagnosis of BoNTA from the injection site depends on clinical, temporal, and electromyographic factors. Clinical expression of spread varies widely, with mechanisms remaining largely unknown, and further prospective, randomized clinical trials are required.