Review of the use of botulinum toxin for hyperhidrosis and cosmetic purposes

Successful Treatment of Schwartz-Jampel Syndrome with Botulinum Toxin Type A

Schwartz-Jampel syndrome (SJS) is a rare autosomal recessive disorder characterized by typical facial dysmorphism, generalized muscle stiffness, joint contracture, and skeletal abnormalities. This condition is caused by mutations in the heparan sulfate proteoglycan 2 (HSPG2) gene, which encodes perlecan, a component of the basement membrane. The management of patients with SJS primarily aims to alleviate symptoms related to muscle stiffness. In this report, we describe a male patient with SJS type 1A. Trio whole-exome sequencing identified a pathogenic mutation (NM_001291860.1: c.10897C>T; p.Arg3633Ter) and variants of unknown significance (NM_001291860.2: c.413+10G>T). The patient experienced difficulty in opening his eyes and mouth, which significantly limited his daily activities. Botulinum toxin A injection was administered and demonstrated significant clinical improvement after the treatment.

Different Glabellar Contraction Patterns in Chinese and Efficacy of Botulinum Toxin Type A for Treating Glabellar Lines: A Pilot Study

BACKGROUND

Published research studies have described the existence of 5 glabellar contraction patterns. Botulinum toxin A (BoNTA) has been an approved and effective treatment of glabellar lines.

OBJECTIVE

To study the pattern and frequency of glabellar contraction patterns in the Chinese population. To compare injection patterns and doses of BoNTA in Westerners within China.

METHODS

Four hundred fifty-six healthy volunteers were randomly recruited. Photographs both in static and in frown state were taken and classified based on the method of 5 glabellar line patterns. The severity of the glabellar lines both at repose and during forced contraction was assessed by the Facial Wrinkle Scale (FWS). Subsequently, 75 of them were treated with BoNTA.

RESULTS

The frequency of the various glabellar line patterns differs greatly between Chinese and Westerners with the "Converging arrows" pattern being the most common type and the "V" pattern being the least common when compared with the Westerners. Lower doses of BoNTA significantly improved the static and dynamic glabellar lines in the Chinese.

CONCLUSION

The classification of 5 glabellar patterns is compatible for the Chinese population despite different proportions. The dosage of BoNTA should be less than 20 U during treatment in China with lowered incidence of complications.

Comparative characterization of botulinum neurotoxin subtypes F1 and F7 featuring differential substrate recognition and cleavage mechanisms

BoNT/F7, one of the seven subtypes of botulinum neurotoxin type F (F1 to F7), is the second-most divergent subtype of this group. Despite sharing >60% identity with BoNT/F1 at both holotoxin and enzymatic domain levels, it requires an N-terminal extended peptide substrate for efficient substrate cleavage, suggesting its unique substrate recognition and specificity mechanism. Substrate mapping and saturation mutagenesis analysis revealed that VAMP2 (20-65) was likely a minimally effective substrate for LC/F7 (light chain of BoNT/F7), and in addition, LC/F7 recognized VAMP2 in a unique way, which differed significantly from that of LC/F1, although both of them share similar substrate binding and hydrolysis mode. LC/F7 utilizes distinct pockets for specific substrate binding and recognition in particular for the B1, B2 and S2 sites recognitions. Our findings provide insights into the distinct substrate recognition features of BoNT subtypes and useful information for therapy development for BoNT/F.

Substrate-based inhibitors exhibiting excellent protective and therapeutic effects against Botulinum Neurotoxin A intoxication

Potent inhibitors to reverse Botulinum neurotoxins (BoNTs) activity in neuronal cells are currently not available. A better understanding of the substrate recognition mechanism of BoNTs enabled us to design a novel class of peptide inhibitors which were derivatives of the BoNT/A substrate, SNAP25. Through a combination of in vitro, cellular based, and in vivo mouse assays, several potent inhibitors of approximately one nanomolar inhibitory strength both in vitro and in vivo have been identified. These compounds represent the first set of inhibitors that exhibited full protection against BoNT/A intoxication in mice model with undetectable toxicity. Our findings validated the hypothesis that a peptide inhibitor targeting the two BoNT structural regions which were responsible for substrate recognition and cleavage respectively could exhibit excellent inhibitory effect, thereby providing insight on future development of more potent inhibitors against BoNTs.

Exploration of endogenous substrate cleavage by various forms of botulinum neurotoxins

Botulinum neurotoxins are the most potent protein neurotoxin known to human. The dual roles of BoNTs as both the causative agent of human botulism and a widely used protein-based therapeutic agent for treatment of numerous neuromuscular disorders/cosmetic uses make it an extremely hot topic of research. Biochemical characterization of these toxins was mainly confined to the recombinant light chains and substrate and little is known about their efficiency on the cleavage of endogenous substrates. In the present study, we showed that BoNTs exhibited variable activities on their endogenous substrates and that their efficiency to cleave recombinant and endogenous substrate was not consistent, presumably due to the differential recognition of their respective substrates in the natural SNARE complex format. Through testing the combinatorial effects of different BoNTs on cleavage of endogenous substrates, we showed that the combinations of LC/A and LC/B, as well as LC/A and LC/F, could enhance the activity of each individual BoNT. This finding may shed light on the future development of new BoNT serotypes for clinical application, and formulation of combinatorial uses of different BoNTs to minimize the development of immuno-resistance by using a lower amount of individual type.

Engineering Clostridia Neurotoxins with elevated catalytic activity

BoNT/B and TeNT cleave substrate VAMP2 at the same scissile bond, yet these two toxins showed different efficiency on substrate hydrolysis and had different requirements for the recognition of P2' site of VAMP2, E(78). These differences may be due to their different composition of their substrate recognition pockets in the active site. Swapping of LC/T S1' pocket residue, L(230), with the corresponding isoleucine in LC/B increased LC/T activity by ∼25 fold, while swapping of LC/B S1' pocket residue, S(201), with the corresponding proline in LC/T increased LC/B activity by ∼10 fold. Optimization of both S1 and S1' pocket residues of LC/T, LC/T (K(168)E, L(230)I) elevated LC/T activity by more than 100-fold. The highly active LC/T derivative engineered in this study has the potential to be used as a more effective tool to study mechanisms of exocytosis in central neuron. The LC/B derivative with elevated activity has the potential to be developed into novel therapy to minimize the impact of immunoresistance during BoNT/B therapy.

Unique substrate recognition mechanism of the botulinum neurotoxin D light chain

Botulinum neurotoxins are the most potent protein toxins in nature. Despite the potential to block neurotransmitter release at the neuromuscular junction and cause human botulism, they are widely used in protein therapies. Among the seven botulinum neurotoxin serotypes, mechanisms of substrate recognition and specificity are known to a certain extent in the A, B, E, and F light chains, but not in the D light chain (LC/D). In this study, we addressed the unique substrate recognition mechanism of LC/D and showed that this serotype underwent hydrophobic interactions with VAMP-2 at its V1 motif. The LC/D B3, B4, and B5 binding sites specifically recognize the hydrophobic residues in the V1 motif of VAMP-2. Interestingly, we identified a novel dual recognition mechanism employed by LC/D in recognition of VAMP-2 sites at both the active site and distal binding sites, in which one site of VAMP-2 was recognized by two independent, but functionally similar LC/D sites that were complementary to each other. The dual recognition strategy increases the tolerance of LC/D to mutations and renders it a good candidate for engineering to improve its therapeutic properties. In conclusion, in this study, we identified a unique multistep substrate recognition mechanism by LC/D and provide insights for LC/D engineering and antitoxin development.

Clinical uses of botulinum neurotoxins: current indications, limitations and future developments

Botulinum neurotoxins (BoNTs) cause flaccid paralysis by interfering with vesicle fusion and neurotransmitter release in the neuronal cells. BoNTs are the most widely used therapeutic proteins. BoNT/A was approved by the U.S. FDA to treat strabismus, blepharospam, and hemificial spasm as early as 1989 and then for treatment of cervical dystonia, glabellar facial lines, axillary hyperhidrosis, chronic migraine and for cosmetic use. Due to its high efficacy, longevity of action and satisfactory safety profile, it has been used empirically in a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, and painful disorders. Currently available BoNT therapies are limited to neuronal indications with the requirement of periodic injections resulting in immune-resistance for some indications. Recent understanding of the structure-function relationship of BoNTs prompted the engineering of novel BoNTs to extend therapeutic interventions in non-neuronal systems and to overcome the immune-resistance issue. Much research still needs to be done to improve and extend the medical uses of BoNTs.

Long-term follow-up after botulinum toxin A (BTX-A) injection into the detrusor for treatment of neurogenic detrusor hyperactivity in children

Purpose

To prove the long-term efficacy of BTX-A injection in the management of children with neurogenic detrusor hyperactivity.

Materials and methods

28 out of 145 children with neurogenic bladder (15 male and 13 female, mean age 10.7 years) who were treated between 2002 and 2010 and became non-responders to conservative treatment were included into the retrospective study.

We injected 10-12 U/kg of BTX-A (Botox^®) into the detrusor at 20-30 sites, sparing the trigone. The mean follow-up was 48 months (range 6-84 months).

Results

Group 1. 14 patients had a single injection of BTX-A. Five of them were successful.

Mean bladder reflex volume increased (from 62.9 to 117.5 ml), maximum detrusor pressure decreased (from 59 to 37.5 cm H₂O), detrusor compliance increased (from 4.8 to 9.5 ml/cm H₂O), and leak-point-pressure decreased (from 46.5 to 24.2 cm H₂O). Four patients did not respond and were treated by ileocystoplasty. Another five were lost to follow-up. Group 2. 14 patients had repeated (mean 2.5) injections of BTX-A with a mean interval of 13.7 months. In thirteen patients, urodynamic parameters of the first and last injection were similar to those obtained in Group 1, showing a good response. One patient received an ileocystoplasty.

Conclusion

BTX-A is a safe alternative in the treatment of detrusor hyperactivity in children with myelomeningocele (MMC). The efficacy lasted a mean of 12 months and urodynamic response was unchanged even after several injections. In our series, 21.7% of children with severe low-compliance bladders were non-responders.

Diffusion of botulinum toxins

BACKGROUND

It is generally agreed that diffusion of botulinum toxin occurs, but the extent of the spread and its clinical importance are disputed. Many factors have been suggested to play a role but which have the most clinical relevance is a subject of much discussion.

METHODS

This review discusses the variables affecting diffusion, including protein composition and molecular size as well as injection factors (e.g., volume, dose, injection method). It also discusses data on diffusion from comparative studies in animal models and human clinical trials that illustrate differences between the available botulinum toxin products (onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB).

RESULTS

Neither molecular weight nor the presence of complexing proteins appears to affect diffusion; however, injection volume, concentration, and dose all play roles and are modifiable. Both animal and human studies show that botulinum toxin products are not interchangeable, and that some products are associated with greater diffusion and higher rates of diffusion-related adverse events than others.

DISCUSSION

Each of the botulinum toxins is a unique pharmacologic entity. A working knowledge of the different serotypes is essential to avoid unwanted diffusion-related adverse events. In addition, clinicians should be aware that the factors influencing diffusion may range from properties intrinsic to the drug to accurate muscle selection as well as dilution, volume, and dose injected.

Specificity of botulinum protease for human VAMP family proteins

The botulinum neurotoxin light chain (BoNT-LC) is a zinc-dependent metalloprotease that cleaves neuronal SNARE proteins such as SNAP-25, VAMP2, and Syntaxin1. This cleavage interferes with the neurotransmitter release of peripheral neurons and results in flaccid paralysis. SNAP, VAMP, and Syntaxin are representative of large families of proteins that mediate most membrane fusion reactions, as well as both neuronal and non-neuronal exocytotic events in eukaryotic cells. Neuron-specific SNARE proteins, which are target substrates of BoNT, have been well studied; however, it is unclear whether other SNARE proteins are also proteolyzed by BoNT. Herein, we define the substrate specificity of BoNT-LC/B, /D, and /F towards recombinant human VAMP family proteins. We demonstrate that LC/B, /D, and /F are able to cleave VAMP1, 2, and 3, but no other VAMP family proteins. Kinetic analysis revealed that all LC have higher affinity and catalytic activity for the non-neuronal SNARE isoform VAMP3 than for the neuronal VAMP1 and 2 isoforms. LC/D in particular exhibited extremely low catalytic activity towards VAMP1 relative to other interactions, which we determined through point mutation analysis to be a result of the Ile present at residue 48 of VAMP1. We also identified the VAMP3 cleavage sites to be at the Gln 59-Phe 60 (LC/B), Lys 42-Leu 43 (LC/D), and Gln 41-Lys 42 (LC/F) peptide bonds, which correspond to those of VAMP1 or 2. Understanding the substrate specificity and kinetic characteristics of BoNT towards human SNARE proteins may aid in the development of novel therapeutic uses for BoNT.

Time-dependent botulinum neurotoxin serotype A metalloprotease inhibitors

Botulinum neurotoxins (BoNTs) are the most lethal of biological substances, and are categorized as class A biothreat agents by the Centers for Disease Control and Prevention. There are currently no drugs to treat the deadly flaccid paralysis resulting from BoNT intoxication. Among the seven BoNT serotypes, the development of therapeutics to counter BoNT/A is a priority (due to its long half-life in the neuronal cytosol and its ease of production). In this regard, the BoNT/A enzyme light chain (LC) component, a zinc metalloprotease responsible for the intracellular cleavage of synaptosomal-associated protein of 25 kDa, is a desirable target for developing post-BoNT/A intoxication rescue therapeutics. In an earlier study, we reported the high throughput screening of a library containing 70,000 compounds, and uncovered a novel class of benzimidazole acrylonitrile-based BoNT/A LC inhibitors. Herein, we present both structure-activity relationships and a proposed mechanism of action for this novel inhibitor chemotype.

Endoscopic thoracic sympathectomy for hyperhidrosis: Technique and results

Outline:

We review the clinical features of hyperhidrosis and the range of treatments used for this condition. We describe in detail the technique of endoscopic sympathectomy. We summarize studies that have reported results of endoscopic sympathectomy. We present new data highlighting the difference in quality of life between patients with hyperhidrosis and controls.

Molecular mechanisms of substrate recognition and specificity of botulinum neurotoxin serotype F

BoNTs (botulinum neurotoxins) are both deadly neurotoxins and natural toxins that are widely used in protein therapies to treat numerous neurological disorders of dystonia and spinal spasticity. Understanding the mechanism of action and substrate specificity of BoNTs is a prerequisite to develop antitoxin and novel BoNT-derived protein therapy. To date, there is a lack of detailed information with regard to how BoNTs recognize and hydrolyse the substrate VAMP-2 (vesicle-associated membrane protein 2), even though it is known to be cleaved by four of the seven BoNT serotypes, B, D, F, G and TeNT (tetanus neurotoxin). In the present study we dissected the molecular mechanisms of VAMP-2 recognition by BoNT serotype F for the first time. The initial substrate recognition was mediated through sequential binding of VAMP-2 to the B1, B2 and B3 pockets in LC/F (light chain of BoNT serotype F), which directed VAMP-2 to the active site of LC/F and stabilized the active site substrate recognition, where the P2, P1' and P2' sites of VAMP-2 were specifically recognized by the S2, S1' and S2' pockets of LC/F to promote substrate hydrolysis. The understanding of the molecular mechanisms of LC/F substrate recognition provides insights into the development of antitoxins and engineering novel BoNTs to optimize current therapy and extend therapeutic interventions.

Small molecule inhibitors as countermeasures for botulinum neurotoxin intoxication

Botulinum neurotoxins (BoNTs) are the most potent of known toxins and are listed as category A biothreat agents by the U.S. CDC. The BoNT-mediated proteolysis of SNARE proteins inhibits the exocytosis of acetylcholine into neuromuscular junctions, leading to life-threatening flaccid paralysis. Currently, the only therapy for BoNT intoxication (which results in the disease state botulism) includes experimental preventative antibodies and long-term supportive care. Therefore, there is an urgent need to identify and develop inhibitors that will serve as both prophylactic agents and post-exposure ‘rescue’ therapeutics. This review focuses on recent progress to discover and develop small molecule inhibitors as therapeutic countermeasures for BoNT intoxication.

Iterative structure-based peptide-like inhibitor design against the botulinum neurotoxin serotype A

The botulinum neurotoxin serotype A light chain (BoNT/A LC) protease is the catalytic component responsible for the neuroparalysis that is characteristic of the disease state botulism. Three related peptide-like molecules (PLMs) were designed using previous information from co-crystal structures, synthesized, and assayed for in vitro inhibition against BoNT/A LC. Our results indicate these PLMS are competitive inhibitors of the BoNT/A LC protease and their K_i values are in the nM-range. A co-crystal structure for one of these inhibitors was determined and reveals that the PLM, in accord with the goals of our design strategy, simultaneously involves both ionic interactions via its P1 residue and hydrophobic contacts by means of an aromatic group in the P2′ position. The PLM adopts a helical conformation similar to previously determined co-crystal structures of PLMs, although there are also major differences to these other structures such as contacts with specific BoNT/A LC residues. Our structure further demonstrates the remarkable plasticity of the substrate binding cleft of the BoNT/A LC protease and provides a paradigm for iterative structure-based design and development of BoNT/A LC inhibitors.

Analysis of Botulinum Neurotoxin Serotype A Metalloprotease Inhibitors: Analogs of a Chemotype for Therapeutic Development in the Context of a Three-Zone Pharmacophore

Botulinum neurotoxins (BoNTs), and in particular serotype A, are the most poisonous of known biological substances, and are responsible for the flaccid paralysis of the disease state botulism. Because of the extreme toxicity of these enzymes, BoNTs are considered highest priority biothreat agents. To counter BoNT serotype A (BoNT/A) poisoning, the discovery and development of small molecule, drug-like inhibitors as post-intoxication therapeutic agents has been/is being pursued. Specifically, we are focusing on inhibitors of the BoNT/A light chain (LC) (ie, a metalloprotease) subunit, since such compounds can enter neurons and provide post-intoxication protection of the enzyme target substrate. To aid/facilitate this drug development effort, a pharmacophore for inhibition of the BoNT/A LC subunit was previously developed, and is continually being refined via the incorporation of novel and diverse inhibitor chemotypes. Here, we describe several analogs of a promising therapeutic chemotype in the context of the pharmacophore for BoNT/A LC inhibition. Specifically, we describe: 1) the pharmacophoric 'fits' of the analogs and how these 'fits' rationalize the in vitro inhibitory potencies of the analogs and 2) pharmacophore refinement via the inclusion of new components from the most potent of the presented analogs.

Engineering botulinum neurotoxin to extend therapeutic intervention

Clostridium botulinum neurotoxins (BoNTs) are effective therapeutics for a variety of neurological disorders, such as strabismus, blepharospam, hemificial spasm, and cervical dystonia, because of the toxin's tropism for neurons and specific cleavage of neuronal soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptors (SNARE) proteins. Modifying BoNT to bind nonneuronal cells has been attempted to extend therapeutic applications. However, prerequisite to develop nonneuronal therapies requires the retargeting the catalytic activity of BoNTs to nonneuronal SNARE isoforms. Here, we reported the engineering of a BoNT derivative that cleaves SNAP23, a nonneuronal SNARE protein. SNAP23 mediates vesicle-plasma membrane fusion processes, including secretion of airway mucus, antibody, insulin, gastric acids, and ions. This mutated BoNT/E light chain LC/E(K(224)D) showed extended substrate specificity to cleave SNAP23, and the natural substrate, SNAP25, but not SNAP29 or SNAP47. Upon direct protein delivery into cultured human epithelial cells, LC/E(K(224)D) cleaved endogenous SNAP23, which inhibited secretion of mucin and IL-8. These studies show the feasibility of genetically modifying LCs to target a nonneuronal SNARE protein that extends therapeutic potential for treatment of human hypersecretion diseases.

Three-dimensional database mining identifies a unique chemotype that unites structurally diverse botulinum neurotoxin serotype A inhibitors in a three-zone pharmacophore

A search query consisting of two aromatic centers and two cationic centers was defined based on previously identified small molecule inhibitors of the botulinum neurotoxin serotype A light chain (BoNT/A LC) and used to mine the National Cancer Institute Open Repository. Ten small molecule hits were identified, and upon testing, three demonstrated inhibitory activity. Of these, one was structurally unique, possessing a rigid diazachrysene scaffold. The steric limitations of the diazachrysene imposed a separation between the overlaps of previously identified inhibitors, revealing an extended binding mode. As a result, the pharmacophore for BoNT/A LC inhibition has been modified to encompass three zones. To demonstrate the utility of this model, a novel three-zone inhibitor was mined and its activity was confirmed.

Botulinum toxin A injection for primary and recurrent chalazia

BACKGROUND

To study the efficacy and safety of subcutaneous botulinum toxin A injections in the treatment of primary and recurrent chalazia.

METHODS

Prospective, placebo-controlled consecutive case-series trial. Sixty three patients were divided into two groups: group 1 consisting of 32 patients previously diagnosed with and treated for primary or recurrent chalazia with 2-5 international units (IU) in 0.2-0.5 ml of preserved saline solution of botulinum toxin injection, and group 2 consisting of 31 patients receiving placebo. The main outcome measures were localization and duration of the disease, size of chalazion before and after treatment, clinical resolution of chalazion, time to resolution, and complications of treatment.

RESULTS

There was a clinically and statistically significant between-group difference in the rate of therapeutic success and post-therapeutic chalazion regression, but not in the rate of complications.

CONCLUSIONS

Botulinum toxin A injection is effective and safe treatment for primary and recurrent chalazia. Lesion regression that did not respond to the average of two injections would benefit more from surgical excision or systemic antibiotic therapy.

Botulinum neurotoxins: fundamentals for the facial plastic surgeon

The most commonly performed nonsurgical cosmetic procedure in the facial plastic surgery armamentarium involves the various commercial preparations of botulinum neurotoxins. These drugs have undergone a transformation from public health scourge to near ubiquitous therapeutic modality across the entire medical spectrum. Herein, the history of botulinum neurotoxins is reviewed, including an exploration of their pharmacology, neuromuscular junction physiology, a description of the commercially available preparations, and the recent research concerning the practicalities of their clinical use.

Botulinum Toxin in Closed Treatment of Mandibular Condylar Fracture

BACKGROUND

The topic of condylar injury in adults has generated more discussion and controversy than any other in the field of maxillofacial trauma. The treatment of condylar fractures in adults is still a highly debated theme.

METHODS

Patients with unilateral subcondylar or condylar neck fractures of the mandibula without any significant angulation of the condylar head were managed with closed-treatment protocol. Closed treatment was applied through the injection of 100 units of botulinum toxin A, diluted to a concentration of 20 IU/mL, into the muscles of mastication of the fractured side. Masseter and anterior fibers of temporalis muscles were reached through percutaneous extraoral route and 30 IU of the toxin was injected to each muscle. Additional 40 IU of the toxin was injected around the fractured bone fragments through transmucosal intraoral route to paralyze medial and lateral pterygoid muscles as much as possible. An asymmetric occlusal splint was applied for maxillomandibular fixation to restore the vertical height for 10 days. Functional therapy with intermaxillary guiding elastics was advocated for 2 months.

RESULTS

There were no complications related to either toxin injections or splint application procedures. The toxin was effective on all occasions. Fractured condylar process and ramus of the mandibula were in good approximation and remained in reduced positions. None of the patients had any occlusal disturbance, mandibular asymmetry, or joint dysfunction in the follow-up period.

CONCLUSIONS

We believe that modification of treatment options concerning the clinical situation of the patients is the best method for condylar injury. The purpose of this study is to present and discuss the results achieved in closed treatment of a selected group of patients with mandibular condylar fractures to whom botulinum toxin A was injected to relieve the spasm of muscles of mastication, along with special splint application.

A Refined Pharmacophore Identifies Potent 4-Amino-7-chloroquinoline-Based Inhibitors of the Botulinum Neurotoxin Serotype A Metalloprotease

We previously identified structurally diverse small molecule (non-peptidic) inhibitors (SMNPIs) of the botulinum neurotoxin serotype A (BoNT/A) light chain (LC). Of these, several (including antimalarial drugs) contained a 4-amino-7-chloroquinoline (ACQ) substructure and a separate positive ionizable amine component. The same antimalarials have also been found to interfere with BoNT/A translocation into neurons, via pH elevation of the toxin-mediated endosome. Thus, this structural class of small molecules may serve as dual-function BoNT/A inhibitors. In this study, we used a refined pharmacophore for BoNT/A LC inhibition to identify four new, potent inhibitors of this structural class (IC50's ranged from 3.2 to 17 muM). Molecular docking indicated that the binding modes for the new SMNPIs are consistent with those of other inhibitors that we have identified, further supporting our structure-based pharmacophore. Finally, structural motifs of the new SMNPIs, as well as two structure-based derivatives, were examined for activity, providing valuable information about pharmacophore component contributions to inhibition.

Botulinum Toxin in Ophthalmology

Since its introduction into clinical medicine in 1980, botulinum toxin has become a major therapeutic drug with applications valuable to many medical sub-specialties. Its use was spearheaded in ophthalmology where its potential applications have expanded to cover a broad range of visually related disorders. These include dystonic movement disorders, strabismus, nystagmus, headache syndromes such as migraine, lacrimal hypersecretion syndromes, eyelid retraction, spastic entropion, compressive optic neuropathy, and, more recently, periorbital aesthetic uses. Botulinum toxin is a potent neurotoxin that blocks the release of acetylcholine at the neuromuscular junction of cholinergic nerves. When used appropriately it will weaken the force of muscular contraction, or inhibit glandular secretion. Recovery occurs over 3 to 4 months from nerve terminal sprouting and regeneration of inactivated proteins necessary for degranualtion of acetylcholine vesicles. Complications are related to chemodenervation of adjacent muscle groups, injection technique, and immunological mechanisms.

Results of Botilinum Toxin

Schwartz-Jampel syndrome (SJS) is a rare congenital disorder of continuous myotonia, causing visual and eyelid problems such as blepharospasm, acquired ptosis, and blepharophimosis. We report the management of blepharospasm in two sisters with Schwartz-Jampel syndrome with application of botulinum toxin type A (BTX-A), as an alternative to the surgical treatments, such as orbicularis oculi myectomy, levator aponeurosis resection, and lateral canthopexy as described in the literature. Three consequent doses of commercially available BTX-A (Botox-Allergan, Inc. 100 u/via) were injected to orbicularis oculi muscle in two sisters with Schwartz-Jampel syndrome. At the least, the authors waited for a six-month interval to prevent development of sensitivity to BTX-A in patients. No significant improvement was observed after the injection of first dose of BTX-A, with the total dose of 25 units of BTX-A to each orbicularis oculi muscle of the eyes. The muscle tone weakened after the second dose, which was the twice as such of the first applied total dose (50 units of BTX-A to each orbicularis oculi muscle of the eyes) and significant functional and cosmetic improvements were achieved after injection of the third dose, in which the total applied dose was the same as the one applied in second dose. The blepharospasm and eyelid alterations caused by Schwartz-Jampel syndrome should be treated to provide functional and cosmetic improvements. Application of BTX-A to orbicularis oculi muscle for the treatment of blepharospasm could be considered as an alternative to levator resection, and lateral canthopexy in Schwartz-Jampel syndrome.

Botulinum toxin in dermatology - beyond wrinkles and sweat

Botulinum toxin (BTX) types A and B have been used with success in cosmetic dermatology and hyperhidrosis treatment. The present review focuses on other uses of BTX in dermatology. Discussed in particular are the available data on BTX in inflammatory diseases, proctology, and some other indications. From studies in various types of eczema, it seems that BTX-A not only acts as a potent inhibitor of acetylcholine but also as an inhibitor of substance P and of glutamate as well. By those mechanisms, BTX-A may be antipruritic, which may help explain the benefits of BTX-A in lichen simplex and dyshidrotic hand eczema. In Hailey-Hailey disease, facial eccrine hidrocystomas, salivary fistulas, and intrinsic rhinitis, BTX-A blocks the secretion of sweat/saliva/mucus. BTX-A has important applications in proctology where it has become the most powerful nonsurgical therapy for anal fissures. In proctalgia fugax and after hemorrhoidectomy, BTX-A is analgesic. Current treatment applications of BTX-A and its limitations are reviewed in this paper.

Botulinum toxin type A injections: Adverse events reported to the US Food and Drug Administration in therapeutic and cosmetic cases

BACKGROUND

Botulinum toxin type A (BTA) (Botox) received Food and Drug Administration (FDA) approval for therapeutic treatment of strabismus and blepharospasm in 1989, cervical dystonia in 2000, and cosmetic treatment of glabellar wrinkles (Botox Cosmetic) in 2002. In 2002 alone there were approximately 1.1 to 1.6 million patients using cosmetic BTA. Our objective was to review adverse event (AE) reporting to the FDA after BTA administration.

METHODS

We reviewed all (therapeutic and cosmetic use) serious (per FDA regulations) AEs reported to the FDA for the 13.5 years since licensure of the product (December 1989-May 2003) and nonserious AEs reported from December 2001 to November 2002. AEs are reported to the FDA through the MedWatch system.

RESULTS

We reviewed 1437 AE reports; 406 followed therapeutic use of BTA (217 serious and 189 nonserious) and 1031 followed cosmetic use (36 serious and 995 nonserious). Reported AEs occurred predominantly in female patients, with a median age of 50 years. In the year December 2001 to November 2002, when both serious and nonserious reports were evaluated, the proportion of reports classified as serious was 33-fold higher for therapeutic than for cosmetic cases. The 217 serious AEs reported in therapeutic cases involved a wide spectrum of events and included all 28 reported deaths. Among cosmetic users, no deaths were reported and, of the 36 serious AEs, 30 were included as possible complications in the FDA-approved label. The remaining 6 serious AEs did not display a pattern suggesting a common causal relationship to BTA. Among the 995 cosmetic cases reported to have nonserious AEs, most commonly noted were lack of effect (623, 63%), injection site reaction (190, 19%), and ptosis (111, 11%).

CONCLUSIONS

Serious AEs were more likely to be reported for therapeutic than for cosmetic use, which may be related to higher doses, complicated underlying diseases, or both. Among cosmetic cases, few serious AEs were reported, and these were predominantly events that were previously recognized in clinical trials of BTA for the labeled use. This study is limited primarily by the incomplete nature of AE reporting by clinicians. Numerous departures from FDA-approved recommendations for drug dose, dilution, handling, site of injection, and storage were noted in these AE reports.

[Botulinum toxin and medical liability: is the patient sufficiently informed?]

INTRODUCTION

The use of botulinum toxin injection therapy is soaring significantly today, with an ever-wider field of applications despite well-known side effects of the treatment. This article aims at analysing the medicolegal practices of practitioners who use this therapy, especially the information given to patients and finding a common practice for providing that information.

METHODS

We sent a questionnaire to 340 practitioners who might use the therapy (physiatrists, neurologists, ophthalmologists, ENT specialists, plastic surgeons) working in hospitals and in physical therapy and rehabilitation centres in France. Besides mentioning the possible side effects of the therapy, the questionnaire focused on how such information was transmitted before the injection.

RESULTS

Data collection and analysis were performed by use of a spreadsheet software programme. A total of 124 questionnaires were analysed. We did not analyse the items dealing with side effects. Sixty-five percent of the responders said they did not seek statutory authorisation for injections. Only 31% provided written, detailed information and 12% required a signed consent form. Complaints were rare, approximately 12%, were written or verbal, and were always dismissed.

DISCUSSION

Side effects after botulinum toxin injection are clearly described in the medical literature. Therefore, it is of utmost importance for this product to be used therapeutically and only by experienced therapists who will carefully respect the product's standard rules of use and inform their patients to the best of their ability. Issuing a detailed letter of information describing all the side effects seems necessary. We suggest a model information letter such as that provided to the patients in our facility.

CONCLUSION

Botulinum toxin is a very worthwhile product for numerous abnormalities but has side effects, often brief, at the site of the injection. Therefore it is our duty to inform patients effectively.

Conformational sampling of the botulinum neurotoxin serotype a light chain: implications for inhibitor binding

Botulinum neurotoxins (BoNTs) are the most potent of the known biological toxins, and consequently are listed as category A biowarfare agents. Currently, the only treatments against BoNTs include preventative antitoxins and long-term supportive care. Consequently, there is an urgent need for therapeutics to counter these enzymes--post exposure. In a previous study, we identified a number of small, nonpeptidic lead inhibitors of BoNT serotype A light chain (BoNT/A LC) metalloprotease activity, and we identified a common pharmacophore for these molecules. In this study, we have focused on how the dynamic movement of amino acid residues in and surrounding the substrate binding cleft of the BoNT/A LC might affect inhibitor binding modes. The X-ray crystal structures of two BoNT/A LCs (PDB refcodes=3BTA and 1E1H) were examined. Results from these analyses indicate that the core structural features of the examined BoNT/A LCs, including alpha-helices and beta-sheets, remained relatively unchanged during 1 ns dynamics trajectories. However, conformational flexibility was observed in surface loops bordering the substrate binding clefts in both examined structures. Our analyses indicate that these loops may possess the ability to decrease the solvent accessibility of the substrate binding cleft, while at the same time creating new residue contacts for the inhibitors. Loop movements and conformational/positional analyses of residues within the substrate binding cleft are discussed with respect to BoNT/A LC inhibitor binding and our common pharmacophore for inhibition. The results from these studies may aid in the future identification/development of more potent small molecule inhibitors that take advantage of new binding contacts in the BoNT/A LC.

Botulinum toxin type B (Myobloc): pharmacology and biochemistry

Purified toxin complexes have found a niche in the treatment of clinical disorders involving muscle hyperactivity. This report describes the fundamental biochemical properties of the commercially available form of Botulinum Toxin Type B and compares these attributes to the Type A form of the Toxin. Both neurotoxins act to inhibit the release of acetylcholine at the neuromuscular junction, causing muscle paralysis. The different serotypes are structurally and functionally similar; however, specific differences in neuronal acceptor binding sites, intracellular enzymatic sites, and species sensitivities suggest that each serotype is its own unique pharmacologic entity. Data are provided on the biochemical properties and long-term stability of the Type B product, which is uniquely formulated as a liquid product.

Type A botulinum toxin in the upper aspect of the face

The use of botulinum toxin type A (BTX-A) for facial rejuvenation was first systematically developed by Carruthers and Carruthers on the upper aspect of the face. In the early 1990s, the first studies of the cosmetic use of BTX-A were published. BTX-A was only approved in 2002, however, by the U.S. Food and Drug Administration when extensive cosmetic studies were evaluated. The treatment of facial wrinkles with BTX-A has truly changed the concepts held by physicians regarding facial rejuvenation, mainly on the upper aspect of the face. It is one of the most common cosmetic procedures currently performed by physicians.

Botulinum toxin types A and B: comparison of efficacy, duration, and dose-ranging studies for the treatment of facial rhytides and hyperhidrosis

One of the most common etiologic forces for the persistence of facial rhytides is the repetitive contraction of the intrinsic muscles that are necessary for facial expression. These include the forehead lines, crow's feet, glabellar rhytides, and wrinkles in the lower face. Although filling agents such as collagen and laser procedures can help reduce the appearance of these lines, they do not address the underlying forces that cause these wrinkles to persist. Botulinum toxin type-A and type-B are neurotoxins that address these issues and result in the relaxation of the intrinsic facial muscles and subsequent resolution of these dynamic facial rhytides. This article will compare the efficacy, duration, dose ranging studies, and safety in the treatment of facial rhytides with both types of toxins. In addition, the treatment of hyperhidrosis with type-A and type-B botulinum toxin will also be discussed.

The cosmetic use of botulinum toxin type B in the upper face

Facial wrinkles involving the forehead, glabellar, and/or periorbital regions are a common esthetic problem and are directly related to overactivity of the underlying facial musculature. For instance, the development of glabellar wrinkles is related, at least in part, to the dynamics of the underlying procerus, corrugator supercilii, and orbicularis oculi muscles. Facial lines are considered problematic because they produce the appearance of aging. In some cases, they can also be misinterpreted as manifestations of negative emotions (eg, anger, anxiety, sadness), fatigue, or stress. In recent years, botulinum toxin injections have become one of the most popular therapies for the treatment of hyperfunctional facial lines. After injection, the toxin acts to paralyze or weaken facial mimetic muscles. This reduces or eliminates the appearance of wrinkles and is extremely safe.

[Botulism toxin in practice]

Botulinum toxins (A and B) are neurotoxins derived from Clostridium botulinum. Clostridium are anaerobic bacteria. C. botulinum produces exotoxins (A to G) with distinct antigenicities. The neurotoxins inhibit the release of the neurotransmitter acetylcholine from the axon terminals of motor neurons. Botulinum toxin is officially used in clinic for the treatment of muscular hyperactivity (strabismus, blepharospam, cervical dystonia). Botulinum toxins are also used in non recognized clinical applications: neurogenic incontinence, palmar and axillary hyperhidrosis, chronic anal fissure. The respective formulations of Botox, Dysport and Neurobloc are described. Special considerations for administration are introduced.

Comparison of botulinum toxins A and B in the aesthetic treatment of facial rhytides

Botulinum toxin injections have become a popular treatment for minimizing or eliminating facial wrinkles. After injection, the toxin acts to paralyze or weaken facial mimetic muscles. Two antigenically distinct serotypes, botulinum toxin type A (BTX-A) and botulinum toxin type B (BTX-B), are currently available. BTX-A is a lyophilized powder preparation requiring reconstitution; BTX-B is a ready-to-use liquid formulation. Both agents produce the same resultant clinical effect (i.e., muscle weakening). However, in addition to differences with respect to formulation, they are pharmacologically distinct in terms of molecular size, cellular mechanism of action, and species sensitivity. BTX-A has been used for aesthetic purposes for more than 10 years. Clinical studies and observations have shown that it is an effective agent for treating hyperkinetic facial lines. BTX-B was approved for use in cervical dystonia in 2000, but it has been used off-label to treat facial wrinkles as reported in several open-label studies. These preliminary dose-ranging studies have demonstrated that BTX-B is also effective. Both agents are extremely safe nonsurgical modalities for hyperkinetic facial lines. This article reviews the pharmacology and molecular features of BTX-A and BTX-B and highlights some of the key clinical studies that have been published to date with these two agents.