Botulinum toxin as a therapeutic agent

Comparative Pharmacodynamics of Three Different Botulinum Toxin Type A Preparations following Repeated Intramuscular Administration in Mice

Botulinum neurotoxin type A (BoNT/A) causes muscle paralysis by blocking cholinergic signaling at neuromuscular junctions and is widely used to temporarily correct spasticity-related disorders and deformities. The paralytic effects of BoNT/A are time-limited and require repeated injections at regular intervals to achieve long-term therapeutic benefits. Differences in the level and duration of effectivity among various BoNT/A products can be attributed to their unique manufacturing processes, formulation, and noninterchangeable potency units. Herein, we compared the pharmacodynamics of three BoNT/A formulations, i.e., Botox^® (onabotulinumtoxinA), Xeomin^® (incobotulinumtoxinA), and Coretox^®, following repeated intramuscular (IM) injections in mice. Three IM injections of BoNT/A formulations (12 U/kg per dose), 12-weeks apart, were administered at the right gastrocnemius. Local paresis and chemodenervation efficacy were evaluated over 36 weeks using the digit abduction score (DAS) and compound muscle action potential (CMAP), respectively. One week after administration, all three BoNT/A formulations induced peak DAS and maximal reduction of CMAP amplitudes. Among the three BoNT/A formulations, only Coretox^® afforded a significant increase in paretic effects and chemodenervation with a prolonged duration of action after repeated injections. These findings suggest that Coretox^® may offer a better overall therapeutic performance in clinical settings.

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.

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.

Driving Performance in Patients With Idiopathic Cervical Dystonia; A Driving Simulator Pilot Study

Objective: To explore driving performance and driving safety in patients with cervical dystonia (CD) on a simulated lane tracking, intersections and highway ride and to compare it to healthy controls.

Design: This study was performed as an explorative between groups comparison.

Participants: Ten CD patients with idiopathic CD, 30 years or older, stable on botulinum toxin treatment for over a year, holding a valid driver's license and being an active driver were compared with 10 healthy controls, matched for age and gender.

Main outcome measures: Driving performance and safety, measured by various outcomes from the simulator, such as the standard deviation of the lateral position on the road, rule violations, percentage of line crossings, gap distance, and number of collisions. Fatigue and driving effort were measured with the Borg CR-10 scale and self-perceived fitness to drive was assessed with Fitness to Drive Screening.

Results: Except for a higher percentage of line crossings on the right side of the road by controls (median percentage 2.30, range 0.00–37.00 vs. 0.00, range 0.00–9.20, p = 0.043), no differences were found in driving performance and driving safety during the simulator rides. Fatigue levels were significantly higher in CD patients just before (p = 0.005) and after (p = 0.033) the lane tracking ride (patients median fatigue levels before 1.5 (range 0.00–6.00) and after 1.5 (range 0.00–7.00) vs. controls median fatigue levels before and after 0.00 (no range). No significant differences were found on self-perceived fitness to drive.

Conclusion: In patients with CD there were no indications that driving performance or driving safety were significant different from healthy controls in a simulator. Patients reported higher levels of fatigue both before and after driving compared to controls in accordance with the non-motor symptoms known in CD.

Passive Monoclonal and Polyclonal Antibody Therapies

Passive antibody therapies have a long history of use. In the 19th century, antibodies from xenographic sources of polyclonal antibodies were used to treat infections (diphtheria). They were used often as protection from infectious agents and toxins. Complications related to their use involved development of immune complexes and severe allergic reactions. As a result, human source plasma for polyclonal antibodies became the preferential source for antibodies. They are used to treat infection, remove toxins, prevent hemolytic disease of the newborn, modify inflammatory reactions, and control autoimmune diseases. Continued improvements in processing decreased the transfusion/infusion transmission of infections. In the late 20th century (∼1986), monoclonal antibodies were developed. The first monoclonal antibodies were of xenographic source and were wrought with problems of immunogenicity. These forms of antibodies did not gain favor until chimerization took pace in the mid-1990s and in 1998 two monoclonal antibodies were approved one to treat respiratory syncytial virus and the other for breast cancers. Further development of humanized and then fully human monoclonal antibodies has led to an evolution of therapies with these agents. Monoclonal antibodies are being researched or approved to treat a multitude of diseases to include oncologic, inflammatory, autoimmune, cardiovascular, respiratory, neurologic, allergic, benign hematologic, infections, orthopedic, coagulopathy, metabolic and to decrease morbidity of disease (diminution of pain), modify disease progression, and potentially anatomic development. In this chapter, we will review the history of use of these passive antibody therapies, their mechanism of action, pharmacologic-therapeutic classification, particular medical indication, adverse reactions, and potential future use of these medications.

Use of botulinum toxin for movement disorders

The term movement disorders encompasses all disorders hypokinetic and hyperkinetic, which were previously known as extrapyramidal syndromes. With the definition of movement disorders and their diagnostic criteria and classifications, new studies for therapeutics could be performed. New drugs were launched, functional neurosurgery was developed, and the introduction of botulinum toxin (BoNT) for hyperkinesias was introduced. BoNT is an important therapy for dystonia, tics, myoclonus, and tremors. The aim of this review is to present the new and well-established uses of BoNT for movement disorders.

Safety, efficacy, and onset of a novel botulinum toxin type A (Nabota) for the treatment of glabellar frown lines: a single-arm, prospective, phase 4 clinical study

Background

Safety, efficacy, and time to onset of effect of botulinum toxin type A is of importance to persons who seek improvement in glabellar frown lines, but this has not been well studied. The aim of this study was to determine the safety, efficacy, and onset of action of a newly developed botulinum toxin type A (Nabota) for the treatment of glabellar frown lines.

Methods

This was a single-arm, open-label, and phase 4 clinical study. Forty-two subjects with glabellar lines were treated with five times of intramuscular injection of 0.1 mL (4 U/0.1 mL) for a total of 20 U of Nabota. Efficacy and safety were assessed at 2, 3, 4, 5, and 14 days. Efficacy was assessed by the investigator and it was defined as a 1-point change on a 4-point scale.

Results

Improvement in glabellar frown lines at maximum frown was observed in 85.4% of subjects 2 days after administration. Improvement in glabellar lines at rest was observed in 51.2% of subjects 2 days after administration, and the proportion of subjects showing improvement increased with time. No severe adverse events were recorded.

Conclusion

Onset of action was observed in the majority of subjects by 2 days after administration of Nabota. In addition, Nabota was found to be safe and effective for the treatment of glabellar frown lines.

Botulinum toxin therapy: functional silencing of salivary disorders

Botulinum toxin (BTX) is a neurotoxic protein produced by Clostridium botulinum, an anaerobic bacterium. BTX therapy is a safe and effective treatment when used for functional silencing of the salivary glands in disorders such as sialoceles and salivary fistulae that may have a post-traumatic or post-operative origin. BTX injections can be considered in sialoceles and salivary fistulae after the failure of or together with conservative treatments (e.g. antibiotics, pressure dressings, or serial aspirations). BTX treatment has a promising role in chronic sialadenitis. BTX therapy is highly successful in the treatment of gustatory sweating (Frey's syndrome), and could be considered the gold standard treatment for this neurological disorder.

Injectable and topical neurotoxins in dermatology: Basic science, anatomy, and therapeutic agents

Botulinum toxin is a potentially deadly anaerobic bacterial toxin that acts by inhibiting release of acetylcholine at the neuromuscular junction, thereby inhibiting contraction of the exposed striated muscle. There are currently 4 botulinum toxin preparations approved by the US Food and Drug Administration (FDA): onabotulinumtoxin, abobotulinumtoxin, incobotulinumtoxin and rimabotulinumtoxin. While significant overlap exists, each product has unique properties and specifications, including dosing, diffusion, and storage. Extensive physician knowledge of facial anatomy, coupled with key differences of the various neurotoxin types, is essential for safe and successful treatments. The first article in this continuing medical education series reviews key characteristics of each neurotoxin, including new and upcoming agents, and provides an anatomic overview of the most commonly injected cosmetic sites.

Histological and immunohistochemical findings of the action of botulinum toxin in salivary gland: systematic review

The treatment of sialorrhea is necessary for the constant risks posed by hypersalivation. A new therapeutic option comes up with the application of botulinum toxin in salivary glands. However, little is known about its mechanism of action in glandular tissue. Based on the above, this work had the objective to systematically review the literature about the action of botulinum toxin on submandibular and parotid salivary glands tissues. Electronic search was performed in databases of great relevance for this study (PubMed, SciELO, HighWire, Crossref, Scopus, Science Direct, MEDLINE, OLDMEDLINE, Serials Database, NLM Catalog, LILACS and IBECS). Inclusion and exclusion criteria for articles were established, and a total number of 14 articles were selected and used. There are few publications that clarify how the salivary gland acini behave with application of botulinum toxin. Although, the immunohistochemical findings were consistent among authors, showing weak immunoreactivity in glands treated with botulinum toxin. Histometric data are divergent, requiring more detailed studies to answer the questions about the efficacy and safety of botulinum toxin in salivary glands.

Use of Botulinum Neurotoxin in Ophthalmology

Botulinum neurotoxin (BoNT) is the first biological toxin used in the treatment of ophthalmic diseases and to decrease skin wrinkles as an aesthetic agent. When used appropriately, it weakens the force of muscular contraction and/or inhibits glandular secretion. The most common areas for botulinum toxin treatment are the upper face, including the glabella, forehead, brows, and lateral canthal lines, or crow's feet. By relaxing the muscles causing wrinkles, non-permanent results may be achieved with its use. BoNT has gained widespread use in a variety of ophthalmic diseases. The effect of BoNT is temporary, but the therapeutic benefit is usually maintained even after repeated injections. Treatment is usually well tolerated. Complications and side effects associated with the treatment are rare and temporary. Complications occur due to weakness (chemodenervation) of adjacent muscle groups, immunological mechanisms and injection technique. Current therapeutic indications, doses, complications and contraindications of BoNT use in the following disorders related to ophthalmology were investigated: aesthetic use, strabismus, blepharospasm, hemifacial spasm, eyelid retraction, entropion, lacrimal hypersecretion syndrome, and facial paralysis.

Management of neurogenic lower urinary tract dysfunction in multiple sclerosis patients

Multiple sclerosis (MS) can be a debilitating neurological condition that attributes significant morbidity to bladder dysfunction. Although many effective treatment options exist, symptomatic patients are often underdiagnosed and undertreated. The purpose of this article is to give an overview of the current literature including new screening tools to identify symptomatic patients and updates on treatment options including medications, botulinum toxin, and neuromodulation.

Pain Relief in Cervical Dystonia with Botulinum Toxin Treatment

Dystonia is a neurological disorder characterized by intermittent or sustained muscle contractions that cause abnormal, usually repetitive, movements and postures. Dystonic movements can be tremulous and twisting and often follow a pattern. They are frequently associated with overflow muscle activation and may be triggered or worsened by voluntary action. Most voluntary muscles can be affected and, in the case of the neck muscles, the condition is referred to as cervical dystonia (CD), the most common form of dystonia. The high incidence of pain distinguishes CD from other focal dystonias and contributes significantly to patient disability and low quality of life. Different degrees of pain in the cervical region are reported by more than 60% of patients, and pain intensity is directly related to disease severity. Botulinum toxin (BoNT) is currently considered the treatment of choice for CD and can lead to an improvement in pain and dystonic symptoms in up to 90% of patients. The results for BoNT/A and BoNT/B are similar. The complex relationship between pain and dystonia has resulted in a large number of studies and more comprehensive assessments of dystonic patients. When planning the application of BoNT, pain should be a key factor in the choice of muscles and doses. In conclusion, BoNT is highly effective in controlling pain, and its analgesic effect is sustained for a long time in most CD patients.

Botulinum Toxin in Pediatric Neurology: Switching Lanes From Death to Life

Botulinum neurotoxins are natural molecules produced by anaerobic spore-forming bacteria called Clostradium boltulinum. The toxin has a peculiar mechanism of action by preventing the release of acetylcholine from the presynaptic membrane. Consequently, it has been used in the treatment of various neurological conditions related to muscle hyperactivity and/or spasticity. Also, it has an impact on the autonomic nervous system by acting on smooth muscle, leading to its use in the management of pain syndromes. The use of botulinum toxin in children separate from adults has received very little attention in the literature. This review presents the current data on the use of botulinum neurotoxin to treat various neurological disorders in children.

Advances in the management of neurogenic detrusor overactivity in multiple sclerosis

Bladder dysfunction in multiple sclerosis (MS) can be socially disabling, have negative psychological and economic consequences, and impair patients' quality of life. Knowledge of the functional anatomy and physiology of the urinary tract is essential to understand the symptoms associated with central nervous system lesions and the pharmacotherapies used to treat them. Treatments for neurogenic detrusor overactivity (NDO) have consisted mainly of administration of anticholinergic drugs, which have been shown to provide suboptimal clinical benefits and be poorly tolerated. The US Food and Drug Administration (FDA) approval of intravesicular botulinum toxin therapy provides a second-line option for MS patients with NDO not responsive to anticholinergic drugs. We performed a review of key literature pertaining to the intravesicular application of botulinum toxin. In the management of NDO, administration of intravesicular botulinum toxin using clean intermittent catheterization decreases the incidence of urinary tract infections, promotes urinary continence, and improves quality of life for 9 months after a single injection; moreover, those benefits are maintained with repeated injections over time.

Botulinum toxin for prevention of delayed gastric emptying after esophagectomy

Background

Esophageal cancer is among the most common gastrointestinal cancers for which the main treatment is surgery. This study was undertaken to analyze the results of Botox injection in preventing gastric stasis in these patients.

Patients and methods

60 patients with esophageal cancer in the middle and lower third parts were included in our study between 2010 and 2011, and were randomly divided into two groups. In group A, 30 patients underwent pyloroplasty, and in group B, injection of botulinum toxin into the pyloric sphincter muscle was used in 30 patients.

Results

The mean age of these patients was 61 ± 10.7 years and the male/female ratio was 33:27. Isotope scans 3 weeks after surgery showed that 5 patients in group A and 3 in group B had delayed gastric emptying; there was no significant difference between the 2 groups, and the success rate of Botox injection was 90%.

Conclusion

Considering the fact that there was no significant difference between pyloroplasty and Botox injection on gastric emptying after surgery, and given the need to use less-aggressive techniques and facilitate greater use of endoscopic methods, botulinum toxin injection may be used instead of pyloroplasty as a simple, effective, and complication-free method to prevent delayed gastric emptying.

Effects of botulinum toxin A on calf muscles in children with cerebral palsy: a systematic review

OBJECTIVE

To assess the efficacy of botulinum toxin A injection for the management of spastic calf muscles in children with cerebral palsy.

DATA SOURCES

We reviewed all relevant literature indexed in MEDLINE, CINAHL, EMBASE, PEDro and the Cochrane Registered Trials, and also hand reviewed abstracts.

METHODS

Eligible studies were randomized controlled trials that compared botulinum toxin A injection with any type of treatment or no treatment with identical conditions. We extracted data on calf muscle tone, passive ankle range of motion, gait speed, ankle kinematics and Gross Motor Function Measure, and assessed methodological qualities.

RESULTS

Fifteen studies met our inclusion criteria. When botulinum injection was compared with a non-sham control, it was found to be effective at improving calf muscle tone (one month: -2.73 (confidence interval (CI) -3.42 to -2.04), three months: -1.72 (-2.68 to -0.76)), passive ankle range of motion (one month: 3.29 (CI 2.52 to 4.05), three months: 1.00 (CI 0.44 to 1.56)) and gait speed (one month: 0.91 (CI 0.29 to 1.53), three months: 0.61 (CI 0.01 to 1.21)) for four months, as well as Gross Motor Function Measure (2.02 (CI 1.30 to 2.75)) for two months. When compared with sham injection, botulinum injection was only effective on Gross Motor Function Measure (0.98 (CI 0.28 to 1.69)) after four months.

CONCLUSIONS

Although we found evidence supporting the efficacy of botulinum toxin A in studies comparing botulinum injection with non-sham controls, we did not find clear evidence of support in studies comparing botulinum injection with sham injection.

Treatment of severe achalasia during pregnancy with esophagoscopic injection of botulinum toxin A: a case report

A pregnant Thai woman presented with progressive dysphagia starting from the gestational age of 18 weeks. Total parenteral nutrition was administered at 33 weeks of gestation due to severe malnutrition. The fetus was found to be growth restricted. Preliminary diagnosis was esophageal achalasia. Diagnostic and treatment options, including early delivery followed by surgical intervention, temporizing pneumatic dilation and intrasphincteric botulinum toxin injection, were discussed before endoscopic examination. The patient preferred temporizing treatments to prolong the pregnancy and to allow for an improvement of her nutritional status to facilitate postpartum recovery. Marked dilatation of the esophagus was found during esophagoscopy. Therefore, local injection of 80 U of botulinum toxin A was chosen over balloon dilation. The swallowing function improved soon after the treatment. The patient and the fetus started to gain weight. Subsequent sonographic examinations did not show any evidence of botulinum toxicity in the fetus. The baby was born at 36 weeks of gestation with an active respiration and preserved muscle tones. Breast-feeding was withheld. The patient remained asymptomatic for at least 6 weeks after delivery. There have been reports of an intentional use of botulinum toxin in selected cases of unremitting movement disorder during pregnancy. No deleterious effects to the mothers or the babies were found in local injection with limited dosage after the first trimester. The authors cannot encourage the routine administration of this neurotoxin for the treatment of achalasia during pregnancy. However, this report provides additional information of botulinum toxin use in pregnant women.

Reduction of EEG Myogenic Artifact with Botulinum Toxin during Video-EEG Monitoring

PURPOSE

To determine whether EEG myogenic artifact during video-EEG monitoring (VEM) is reduced with targeted scalp botulinum toxin (BTX-A) injections.

METHODS

Twelve consecutive patients scheduled for presurgical VEM were treated 2-3 weeks before admission with subcutaneous BTX-A injections at specific EEG electrode locations. On the basis of clinical data available before VEM, four subjects were treated unilaterally (group 1) and eight bilaterally (group 2). BTX-A efficacy was assessed quantitatively in group 1 subjects by comparing high-frequency (20-100 Hz) power at homologous "treated" and "untreated" electrodes during voluntary forceful jaw closure. The clinical impact of BTX-A treatment was assessed by determining whether > or =5 of the first 10 s of each ictal recording was obscured by muscle artifact, and whether residual myogenic artifact on BTX-A-"treated" electrodes rendered these ictal EEG segments impossible to interpret.

RESULTS

BTX-A treatment reduced high-frequency power by a mean of 53% at electrodes T3/T4 and 52% at electrodes F7/F8. None of 49 ictal EEGs had > or =5 of the first 10 s obscured by myogenic artifact, and all of these ictal epochs were interpretable. Adverse events were limited to two subjects who complained of transient difficulty chewing tough foods.

CONCLUSIONS

Scalp-muscle BTX-A treatment before VEM significantly reduces myogenic artifact in subsequent EEG recordings, including ictal EEG. The clinical utility of this technique for improved or more-rapid seizure localization will be determined only by large, blinded, prospective trials.

Botulinum toxin: a novel therapeutic option for bronchial asthma?

Two components are essential for the development of an attack of bronchial asthma: inflammation and bronchoconstriction, the latter being mediated by smooth muscle contraction. Despite the efficacy of chronic therapy, many asthmatics relapse. Measures to inhibit contraction of the airway smooth muscle, such as vagotomy and thermoablation, may decrease the bronchoconstrictor component of the asthma attack and help to decrease morbidity and mortality from the disease. Botulinum toxin acts to weaken skeletal and smooth muscle by preventing the docking of the acetylcholine vesicle on the inner surface of the presynaptic membrane, thus causing chemical denervation and paresis of skeletal or smooth muscle. We explore the possibility that administration of botulinum toxin may achieve the same effect in bronchial asthma and examine the evidence to support this hypothesis.

Treatment of Chronic Low Back Pain With Successive Injections of Botulinum Toxin A Over 6 Months

OBJECTIVES

The aim of this study was to evaluate the effects of two successive neurotoxin treatments for chronic low back pain using multiple pain rating scales in an open-label, prospective study.

METHODS

Adult patients with chronic low back pain received multiple paraspinal muscle injections with a maximum dosing of 500 units of botulinum A toxin per session. Those with a beneficial clinical response received a second treatment at 4 months. Pain was assessed by visual analog scale (VAS), modified low back pain questionnaire (OLBPQ), and a clinical low back pain questionnaire (CLBPQ) at baseline, 3 weeks, 2 months, 4 months, and 6 months after the first treatment.

RESULTS

Eighteen women and 42 men, ages 21 to 79 years (mean 46.6 years), with low back pain of a mean duration of 9.1 years were included. Significant improvement in back and radicular pain occurred at 3 weeks in 60% and at 2 months in 58% of the cohort. Beneficial clinical response to the first injection predicted response to reinjection in 94%. A significant minority of patients had a sustained beneficial effect from the first injection at 4 (16.6%) and 6 months (8.3%). Two patients had a transient flu-like reaction after the initial treatment.

CONCLUSIONS

Botulinum toxin A improves refractory chronic low back pain with a low incidence of side effects. The beneficial clinical response is sustained with a second treatment.

Topical botulinum toxin to treat hyperhidrosis? No sweat!

Palmar, plantar and axillary hyperhidrosis, though benign, may be burdensome and occupationally restrictive, even hazardous. Treatment modalities range from topical antiperspirants, iontophoresis, systemic medications such as anticholinergics and benzodiazepines and injections of botulinum toxin, to thoracic sympathectomy. Intradermal injections of botulinum toxin (BTX), though effective, are painful especially when multiple injections are required. Iontophoretic administration of BTX has been described, the BTX entering the eccrine sweat glands via the sweat pores and through the sweat ducts. We postulate that BTX can be administered topically, either unassisted or assisted by application of an electrical gradient, low-frequency ultrasound or excipients such as dimethylsulfoxide. We examine the rationale and feasibility for such a treatment modality and route of administration.

Achalasia in a patient with gastroesophageal varices: problematic treatment decisions

The coexistence of achalasia and gastroesophageal varices has been reported sporadically in the English medical literature. We report the case of a 60-year-old Hispanic woman with cryptogenic cirrhosis who was referred for a liver transplant evaluation and subsequently developed progressive dysphagia to both solids and liquids as well as substernal chest pain and weight loss. Endoscopy revealed the presence of grade I esophageal varices and large fundic varices, as well as retained liquid and solid food in the distal esophagus. Radiographic and manometric studies were consistent with achalasia. After botulinum toxin (Botox) injections were no longer effective a transjugular intrahepatic portosystemic shunt was performed for portal decompression before proceeding with pneumatic dilation. Optimal treatment of these 2 conditions, when they occur simultaneously, is problematic. We discuss this patient's management and our approach to this infrequent combination of diseases.

Botulinum toxin-physiology and applications in head and neck disorders

This article is structured around a literature review that was carried out using Ovid and Medline with the key words "botulinum," "toxin," and "ENT." Botulinum toxin has been used safely in humans for more than 20 years. The effects are transient, such that treatments are required to be repeated at intervals. Its application to ENT provides a useful tool to treat dystonia, autonomic dysfunction, facial nerve paresis, and hyperfunctional lines. It may also be of benefit in laryngeal rebalancing and the treatment of headaches. Further research is being carried out and new indications for treatment with botulinum toxin may include sialorrhea and rhinorrhea.

Botulinum toxin A for the treatment of cervical dystonia

Idiopathic cervical dystonia (ICD) is the most common adult-onset focal dystonia. It is characterised by relatively sustained, involuntary contractions of neck muscles. Injections of botulinum toxin (BTX)-A are safe and effective for the treatment of ICD, and have substantially improved its treatment. BTX-A is manufactured by Allergan Pharmaceuticals in the US and Ireland, and is distributed as Botox. In Europe, BTX-A is manufactured and distributed by Ipsen Pharmaceuticals as Dysport. Success rates for BTX-A injections for ICD ranges 64-90%, with 76-93% of injected patients experiencing pain reduction. Side effects are generally mild and include dysphagia and neck weakness.

Basic immunological aspects of botulinum toxin therapy

Previous studies in this laboratory had mapped the immune recognition profile of the regions recognized antibodies (Abs) and by T cells on the protective H(C) domain (C-terminal fragment corresponding to residues 855-1296 of the heavy chain) of botulinum neurotoxin serotype A (BoNT/A). The localization of these regions has several potential applications and has provided a basis for the understanding of immunoresistance to treatment. We briefly outline these localized regions and discuss the impact of these findings on the immunotherapeutic applications of BoNT/A. Immunoresistance to toxin therapy can appear in some patients after a few injections with the toxin. Our epitope mapping studies have shown that several factors can influence the immune response to the toxin. These factors include dose, duration of treatment, frequency of immunization, and quality of the toxin. The immune response to the whole toxin is under genetic control, and the response to each epitope is under separate genetic control. Therefore, the appearance of blocking Abs (i.e., immunoresistance) in patients might be controlled by the major histocompatability of the host. Once a patient becomes immunoresistant to one toxin then switching to another toxin will most often be of limited and short-lived benefit, because the patient becomes rapidly immunoresistant to the second toxin. Finally, because of the considerable structural homology between tetanus neurotoxin (TeNT) and BoNTs, it is possible, although not certain, that a prior active immune response to TeNT might play some role in the early appearance on anti-BoNT Abs in some patients.

Molecular targets of botulinum toxin at the mammalian neuromuscular junction

The molecular targets of botulinum neurotoxins (BoNTs) are SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein-receptor) proteins necessary for neurotransmitter release. BoNT are powerful therapeutic agents in the treatment of numerous neurological disorders. The goals of this study were to (1) assess toxin diffusion by measuring substrate cleavage in adjacent and distant muscles, and (2) characterize the clinical course using SNARE protein chemistry. A small volume of BoNT/A was injected unilaterally into the mouse gastrocnemius muscle. Motor impairment was limited to the toxin-treated limb. No systemic illness or deaths occurred. At five time points, a subset of mice were killed, and muscles from both hindlimbs, and the diaphragm, were collected. Protein samples were examined for changes in SNAP-25 (synaptosomal-associated protein of Mr = 25 kDa) using immunochemistry. SNAP-25 cleavage product was noted in the toxin-treated limb as early as 1 day postinjection and continued through day 28. Onset and peak levels of substrate cleavage corresponded to the onset and peak clinical response. Cleavage was observed in adjacent and distant muscles, demonstrating that substrate cleavage is a sensitive indicator of toxin diffusion. Significant increases in full-length SNAP-25 and vesicle-associated membrane protein II were evident early in the impaired limb and continued through day 28. The increased SNARE protein most likely originates from nerve terminal sprouts.

Botulinum toxin therapy in pain management

BTs seem to be a useful treatment in refractory MPS and headache. Presumably BTs work by breaking the spasm or pain cycle giving the patient a "window of opportunity" for traditional conservative measures to have a greater beneficial impact, but several studies suggest that a direct antinociceptive effect distinct from any reduction in muscle spasm may be at play. The major benefit of BTs compared with standard therapies is duration of response. We do not advocate that BTs be used as a first line treatment for MPS or headache. However, in refractory cases where nothing else has worked, it may offer a chance for improvement or cure not otherwise available. For now, it remains an off label, but increasingly accepted, approach in-patients with refractory myofascial pain and headache, who despite multidisciplinary approaches, continue to suffer.

Contraindications and complications with the use of botulinum toxin

Cosmetic use of BTX has skyrocketed in recent years, especially since the approval of BTX-A for treatment of glabellar lines. Complications and adverse reactions can easily arise, particularly for the novice injector. This paper provides insights from an experienced physician on how to avoid these complications, and how to treat them when and if they occur. The main cosmetic uses for BTX are analyzed for possible complications and adverse events. Injection techniques are discussed. Comparisons between BTX-A and BTX-B are given to point out the need for different injection techniques based on the product being used. Treatment recommendations for the Glabella, Brow, Crow's Feet, Upper Lip Wrinkling/Lines, Depressor Anguli Oris, Nasolabial Folds, Mentalis, Neck and Hyperhidrosis are discussed, as well as systemic complications. It is important for the injecting physician to be familiar with these potential complications, even though the use of BTX has been safe and generally well tolerated, because it will lead to even greater success with the use of BTX.

A highly sensitive immuno-polymerase chain reaction assay for Clostridium botulinum neurotoxin type A

Our goal was to develop a sensitive method for detecting Clostridium botulinum neurotoxin type A (BoNT/A). We were able to detect BoNT/A in the femtogram (10(-15)g) range using an indirect immuno-polymerase chain reaction (immuno-PCR) assay and an indirect sandwich immuno-PCR assay. For the indirect immuno-PCR assay, enzyme-linked immunosorbent assay (ELISA) plates were coated with BoNT/A that was recognized by anti-BoNT/A monoclonal antibody. For the indirect sandwich immuno-PCR assay, the monoclonal antibody was immobilized on ELISA plates for detecting BoNT/A that was recognized by its polyclonal antibodies. Reporter DNA was prepared by PCR amplification using biotinylated 5'-primers, and it was coupled with biotinylated antibodies through streptavidin. In order to increase sensitivity and reduce background noise, the amounts of reporter DNA (ranging from 50 fg to 50 ng) and streptavidin (ranging from 0.125 ng to 8 ng) were optimized. Using the optimized concentration of reporter DNA and streptavidin, both indirect and indirect sandwich immuno-PCR assays detected BoNT/A as low as 50 fg. These results are a 10(5)-fold improvement over conventional indirect ELISA and indirect sandwich ELISA methods. The assays we developed are currently the most sensitive methods for detecting BoNT/A.

Botulinum toxins in neurological disease

Botulinum toxins are among the most potent neurotoxins known to humans. In the past 25 years, botulinum toxin has emerged as both a potential weapon of bioterrorism and as a powerful therapeutic agent, with growing applications in neurological and non-neurological disease. Botulinum toxin is unique in its ability to target peripheral cholinergic neurons, preventing the release of acetylcholine through the enzymatic cleavage of proteins involved in membrane fusion, without prominent central nervous system effects. There are seven serotypes of the toxin, each with a specific activity at the molecular level. Currently, serotypes A (in two preparations) and B are available for clinical use, and have been shown to be safe and effective for the treatment of dystonia, spasticity, and other disorders in which muscle overactivity gives rise to symptoms. This review focuses on the pharmacology, electrophysiology, immunology, and application of botulinum toxin in selected neurological disorders.

The Use of Botulinum Toxins for Chronic Pain and Headaches

The use of botulinum toxin in the management of various neurologic and non-neurologic disorders has grown considerably over the past decade. At the same time, new information regarding the mechanism of action of these toxins has evolved allowing for a greater understanding of the versatility of these agents. Although two types of botulinum toxin (type A Botox and type B Myobloc ) are commercially available in the US, most studies of the use of these toxins for the management of chronic pain and headache have been completed with type A. Data from open-label and retrospective studies as well as clinical practice suggest as strongly as possible that there is a role for these agents, especially Botox, in the management of several chronic headache disorders, including chronic migraine, chronic tension-type, cervicogenic, and cluster headache. Emerging data regarding the use of these agents for so-called "analgesic-rebound" headache also appear impressive; however, as of yet, no multicenter, randomized, controlled studies for any headache type have been published that confirm the results seen in noncontrolled studies. Nevertheless, the benefit that some patients experience from this agent is impressive, and this drug appears for many to modify the disorder in a very positive manner. In a similar fashion, data for other pain states are often restricted to open-label and case study approaches; however, clinical experience and some of the available studies (even small controlled studies) suggest a role for the toxins in the management of various chronic pain states, such as myofascial pain, low back pain, and neuropathic pain. One of the greatest challenges ahead for all interested in this area is confirming the benefit seen clinically through appropriately designed multicenter, randomized, controlled studies.

Use of botulinum toxin in the treatment of chronic myofascial pain

BACKGROUND

Myofascial pain syndrome (MPS) is defined as acute or chronic pain with sensory or motor autonomic symptoms, referred from active myofascial triggering points with associated dysfunction. Previous studies have suggested the usefulness of botulinum toxin A (BTX-A) in the treatment of MPS since it is capable of controlling muscular spasms, as well as other alternative mechanisms of action.

OBJECTIVES

To analyze the efficacy of BTX-A treatment and its effect on daily life activities assessing pain reduction using a visual analogue scale (VAS); degree of improvement in physical impairment and disability scoring in the Oswestry low back pain questionnaire; and psychologic status using the Hospital Anxiety and Depression Scale (HAD), in patients suffering from MPS.

METHOD

An open-label interventional prospective trial was conducted in 77 patients diagnosed of refractory MPS (defined as the presence of muscle spasm with pain on mobilization or stretching, plus the existence of trigger points with associated referred pain), resistant to both conservative management and to physical therapy. The BTX-A dosages for the different muscles were chosen according to a standardized protocol. Electromyographic guidance was used to localize the motor end plate prior to injection in superficial muscles; while fluoroscopic guidance was employed to evidence intramyofascial spread of the contrast solution within deep muscles. The assessment of treatment efficacy was based on a pain VAS applied before enrollment, at 15, 30, and 90 days and upon completion of the study; the Lattinen test to establish a relationship between pain intensity and its corresponding impact on daily living; and the HAD scale to assess psychologic stress, performed both before treatment and at the end of the study; and the Oswestry Questionnaire was used to evaluate patients' ability to carry out daily life activities according to their degree of physical impairment and disability scores.

RESULTS

The global analysis revealed a positive correlation between the VAS score prior to treatment and the scoring at 15, 30, and 90 days. This correlation was maintained when analyzing independently for superficial or deep muscles. The correlation coefficients for HAD scores and the Lattinen test values showed a significant association between pre- and post-treatment findings. No adverse events were recorded for 83.1% of the cases.

CONCLUSIONS

The results of this study are consistent with other studies showing the efficacy of BTX-A for treating pain in MPS. The evaluation of the psychologic dimension of this disorder and its associated disability can provide valuable information for the adequate management of these patients and for assessing treatment outcome.

A high-affinity competitive inhibitor of type A botulinum neurotoxin protease activity

The peptide N-acetyl-CRATKML-amide is an effective inhibitor of type A botulinum neurotoxin (BoNT A) protease activity [Schmidt et al., FEBS Lett. 435 (1998) 61-64]. To improve inhibitor binding, the peptide was modified by replacing cysteine with other sulfhydryl-containing compounds. Ten peptides were synthesized. One peptide adapted the structure of captopril to the binding requirements of BoNT A, but it was a weak inhibitor, suggesting that angiotensin-converting enzyme is not a good model for BoNT A inhibitor development. However, replacing cysteine with 2-mercapto-3-phenylpropionyl yielded a peptide with K(i) of 330 nM, the best inhibitor of BoNT A protease activity reported to date. Additional modifications of the inhibitor revealed structural elements important for binding and supported our earlier findings that, with the exception of P1' arginine, subsites on BoNT A are not highly specific for particular amino acid side chains.

Review of the FDA-approved uses of botulinum toxins, including data suggesting efficacy in pain reduction

Botulinum toxin has dramatically improved the treatment of a variety of neurologic disorders. Two botulinum toxin preparations are commercially available in the United States: type A (Botox) and type B (Myobloc). Current indications approved by the United States Food and Drug Administration include cervical dystonia, strabismus, blepharospasm, hemifacial spasm, and glabellar wrinkles for Botox, and cervical dystonia for Myobloc. Botulinum toxin inhibits release of acetylcholine from the neuromuscular junction, resulting in a localized paralysis when minute doses are injected. This mechanism enables botulinum toxin to alleviate symptoms of focal dystonias (which are characterized by excessive muscle contraction), and it may also, along with other theoretical mechanisms, be responsible for pain relief. Studies conducted in patients with cervical dystonia have shown that botulinum toxin effectively reduces pain associated with this disorder, suggesting that this agent may be effective in alleviating other painful syndromes.

Cross reaction of tetanus and botulinum neurotoxins A and B and the boosting effect of botulinum neurotoxins A and B on a primary anti-tetanus antibody response

The present studies were carried out in order to investigate the cross-reaction of botulinum neurotoxins (BoNTs) with human and mouse antibodies against tetanus neurotoxin (TeNT) and determine whether injection of BoNT into a host that has been primed with TeNT would result in boosting of the response to the injected BoNT. Human antisera against TeNT obtained from 9 individuals were found to exhibit substantial cross-reaction with BoNTs A and B. We prepared antibodies (Abs) against inactivated tetanus neurotoxin (TeNT) in outbred mice and determined the binding of these Abs to active TeNT and active botulinum neurotoxins (BoNTs) A and B. Blood samples were collected before immunization (day 0) and on days 42, 82 and 125 after the first injection. The reactions of these sera with the immunizing antigen (inactivated TeNT), active TeNT, active BoNT/A and active BoNT/B were determined. At a fixed dilution (1:62.5 v/v), the sera contained high levels of Abs that reacted with TeNT and also with BoNTs A and B. Throughout the test period (up through day 125) and at different dilutions the cross-reactions of the antisera with BoNT/B were almost twice those with BoNT/A. The reactions of the antisera with the immunizing antigen (inactive TeNT) or with active TeNT were essentially equal throughout the dilution range tested (1:16-1:500 v/v). To determine whether injection of BoNT/A or B into a host that had been primed with TeNT resulted in boosting of the response to the priming antigen (TeNT) as well as BoNT/A or B, mice were primed with TeNT and boosted 21 days later with TeNT, BoNT/A or BoNT/B. Appropriate controls were also employed. Blood samples were collected prior to TeNT priming (day -1) and on days 21, 32, 46 and 67 after priming. In TeNT-primed mice, BoNTs A or B boosted the anti-TeNT Ab responses slightly but had no significant boosting effect on the Ab populations that bind to BoNTs A or B. It is concluded that while Abs against TeNT cross react with BoNTs and the cross reaction with BoNT/B is almost double that of BoNT/A, injection of BoNTs A or B in the presence of a prior active immunity against TeNT is not very likely to make the host mount an Ab response against the injected BoNT.

Complications and adverse reactions with the use of botulinum toxin

Botulinum toxins are the causative agents of the severe food-borne illness botulism. With lethal doses approximating 10(-9) g/kg body weight, these neurotoxins represent some of the most toxic naturally occurring substances. Regardless, botulinum toxin is considered a safe therapy for inappropriate muscle spasms with adverse effects being typically self-limited. This article deals with some of the complications that have occurred with these treatments. The greatest concern with the use of BOTOX is probably the formation of blocking antibodies leading to nonresponse of subsequent treatment. Prevalence of resistance is less than 5%. Most complications associated with its aesthetic use are few and anecdotal. Nevertheless, the common problems and pitfalls associated with aesthetic treatment of the various areas of the face and neck with botulinum toxin are discussed. Also included are recommendations as to how to avoid these very undesirable, yet common, problems.

High-throughput assays for botulinum neurotoxin proteolytic activity: serotypes A, B, D, and F

Botulinum neurotoxins (BoNT) are zinc metalloproteases that cleave and inactivate cellular proteins essential for neurotransmitter release. Because the paralytic effect of BoNT is a consequence of its enzymatic activity, selective inhibitors may be useful as drugs or as tools for further research. To expedite inhibitor discovery, we developed high-throughput, solid-phase protease activity assays for four of the seven BoNT serotypes: A, B, D, and F. Each assay consisted of a cleavable oligopeptide, based on the natural substrate sequence, labeled with fluorescein and covalently attached to maleimide-activated multiwell plates. Solutions of holotoxin or nontoxic catalytic domain of BoNT were incubated in substrate-coated wells, with or without test compounds, followed by transfer and assay of solubilized product in a multiwell fluorometer. Routine toxin concentrations ranged from 10 to 100 ng/ml, but concentrations as low as 2 ng/ml gave reproducible signals. The fluorescence assays were selective, gave very low background readings, and were stable upon prolonged storage. Using the nontoxic catalytic domain of BoNT A, we determined the relative inhibitory potencies of a family of structurally related pseudotripeptide compounds. Unlike previous methods, our assays did not employ antibodies or reverse-phase extraction steps, only well-to-well transfers, and were easily adapted to a high-throughput automated environment.

Complications and adverse reactions with the use of botulinum toxin

Botulinum toxins are the causative agents of the severe food-borne illness botulism. With lethal doses approximating 10(-9) g/kg body weight, these neurotoxins represent some of the most toxic naturally occurring substances. Regardless, botulinum toxin is considered a safe therapy for inappropriate muscle spasms with adverse effects being typically self-limited. This article deals with some of the complications that have occurred with these treatments. The greatest concern with the use of BOTOX is probably the formation of blocking antibodies leading to nonresponse of subsequent treatment. Prevalence of resistance is less than 5%. Most complications associated with its aesthetic use are few and anecdotal. Nevertheless, the common problems and pitfalls associated with aesthetic treatment of the various areas of the face and neck with botulinum toxin are discussed. Also included are recommendations as to how to avoid these very undesirable, yet common, problems.