Effective long-term treatment with incobotulinumtoxin (Xeomin®) without neutralizing antibody induction: a monocentric, cross-sectional study

Background

Among the spectrum of licensed botulinum neurotoxin preparations incobotulinumtoxin (incoBoNT/A; Xeomin®) is the only one which does not contain complex proteins. Therefore, incoBoNT/A has been suggested to have a low antigenicity, but precise estimations on incidence and prevalence of neutralizing antibody formation during long-term treatment are outstanding so far.

Methods

For the present cross-sectional study, 59 patients having exclusively been treated with incoBoNT/A (mono group) and 32 patients having been treated with other BoNT/A preparations less than nine times and who were then switched to at least 14 sessions of incoBoNT/A treatment (switch group) were recruited from one botulinum toxin outpatient clinic. Side effects and doses were extracted from the charts, and the efficacy of treatment was assessed by the patients using a visual analogue scale (0–100). The prevalence of neutralizing antibodies was tested by means of the mouse hemi-diaphragm assay (MHDA).

Findings

None of the patients in the mono and only two in the switch group had a positive MHDA-test. Across all indications and patients, mean improvement exceeded 67%. Improvement did not depend on age at onset, sex, change of dose or duration of treatment, but on disease entity. In patients with cervical dystonia, improvement was about the same in the mono and switch subgroup, but the last dose was different.

Conclusions

The present study confirms the low antigenicity of incoBoNT/A, which has immediate consequences for patient management, and the use of higher doses and shorter durations of reinjection intervals in botulinum toxin therapy.

IncobotulinumtoxinA: A Highly Purified and Precisely Manufactured Botulinum Neurotoxin Type A

Aesthetic dermatologic applications of botulinum neurotoxin (BoNT), including treatment of glabellar lines, horizontal forehead lines, and crow’s feet, were the most common non-surgical cosmetic procedures in the US in 2017, with high levels of subject satisfaction. Since the first BoNT type A (BoNT-A) formulation was approved in 1989, the number of formulations available on the world’s commercial markets has increased and new approvals are expected. BoNT is produced by Clostridium botulinum in nature as part of a large protein complex. However, the unnecessary clostridial proteins, which dissociate from BoNT under physiological conditions with a half-life of <1 minute, have no role in clinical applications. Data demonstrate that BoNT administration can elicit an immunological response, leading to production of neutralizing antibodies that can be associated with reduced efficacy or treatment non-response. As repeat treatments are required to maintain efficacy, clinicians should be aware of the possibility of antibody development and choose a BoNT with the lowest risk of immunogenicity. IncobotulinumtoxinA is manufactured using advanced technology to precisely isolate the pure BoNT without unnecessary clostridial proteins, and with low immunogenicity and high specific activity. In incobotulinumtoxinA clinical studies, no previously BoNT-naïve subjects developed neutralizing antibodies, and there was no secondary non-response to incobotulinumtoxinA treatment. Here we review the role of unnecessary clostridial proteins in BoNT-A and discuss the unique incobotulinumtoxinA manufacturing and purification process with a focus on the implications for use in aesthetic medicine. J Drugs Dermatol. 2019;18(1):52-57.

Current and future botulinum neurotoxin type A preparations in aesthetics: a literature review

Botulinum neurotoxin type A (BTX-A) preparations are well established for cosmetic use. BTX-A inhibits the release of acetylcholine, resulting in temporary muscle paralysis, which has been utilized successfully to treat glabellar frown lines, periorbital wrinkles and other facial enhancement procedures. Two BTX-A products are approved for aesthetic procedures in the United States (U.S.) and Europe, and a next generation of preparations free from complexing proteins has recently been approved in Germany. Despite established efficacy profiles, concerns remain regarding the propensity for immunogenic reactions, which can lead to premature loss of effect and secondary therapy failure. NT 201 is a BTX-A preparation that is free from complexing proteins and is in the advanced stages of aesthetic development. Pivotal clinical studies in therapeutic indications demonstrate noneriority and comparable safety of NT 201 to another available BTX-A preparation. This article reviews the pharmacologic and clinical profiles of BTX-A preparations currently available and in development. Novel BTX-A preparations may offer advantages over existing products in terms of handling and immunogenicity.

National pholcodine consumption and prevalence of IgE-sensitization: a multicentre study

BACKGROUND

The aim of this study was to test, on a multinational level, the pholcodine (PHO) hypothesis, i.e. that the consumption of PHO-containing cough mixtures could cause higher prevalence of IgE antibodies to PHO, morphine (MOR) and suxamethonium (SUX). As a consequence the risk of anaphylaxis to neuromuscular blocking agents (NMBA) will be increased.

METHODS

National PHO consumptions were derived from the United Nations International Narcotics Control Board (INCB) database. IgE and IgE antibodies to PHO, MOR, SUX and P-aminophenyl-phosphoryl choline (PAPPC) were measured in sera from atopic individuals, defined by a positive Phadiatop test (>0.35 kU(A)/l), collected in nine countries representing high and low PHO-consuming nations.

RESULTS

There was a significant positive association between PHO consumption and prevalences of IgE-sensitization to PHO and MOR, but not to SUX and PAPPC, as calculated both by exposure group comparisons and linear regression analysis. The Netherlands and the USA, did not have PHO-containing drugs on the markets, although the former had a considerable PHO consumption. Both countries had high figures of IgE-sensitization.

CONCLUSION

This international prevalence study lends additional support to the PHO hypothesis and, consequently, that continued use of drugs containing this substance should be seriously questioned. The results also indicate that other, yet unknown, substances may lead to IgE-sensitization towards NMBAs.

Skeletal Muscle Atrophy Induced by Intramuscular Repeated Dose of Botulinum Toxin Type A in Rats

Botulinum toxin type A was intramuscularly administered to Sprague-Dawley rats once a day for 28 days at doses of 1, 3, and 9 ng kg-1 day-1 to investigate the possibility of unanticipated toxicity of repeated dose. A dose-related decrease in body weight gain was noted and lasted throughout the 4-week recovery period. Paralytic gait was a common clinical sign observed in the animals dosed at >or=3 ng kg-1 day-1 and muscle atrophy at 9 ng kg-1 day-1. Decreased creatinine was monitored in both males and females treated at 9 ng kg-1 day-1. Microscopic examination of the quadriceps femoris muscle, the test article application site, confirmed the muscle atrophy with a decrease in myofiber diameter and an increase of myofiber nuclei and intermyofiber connective tissue. Although antibody against botulinum toxin type A was detected in the sera from both males and females at 9 ng kg-1 day-1, no immunogenicity-related changes or lesions were noted. In conclusion, no other side effects of the botulinum toxin type A injection except the decrease in body weight gain and the muscle atrophy at the administration site were noted in the 28-day intramuscular repeated dose study.

Formation of neutralizing antibodies in patients receiving botulinum toxin type A for treatment of poststroke spasticity: a pooled-data analysis of three clinical trials

OBJECTIVE

The purpose of this study was to investigate the incidence of neutralizing antibody (NAb) formation in patients with poststroke spasticity treated with a specific formulation of botulinum toxin type A (BoNTA).

METHODS

Data from 3 previous clinical trials of BoNTA in patients with upper and/or lower limb spasticity were pooled and evaluated. Study 1 was a randomized, double-blind, placebo-controlled, multicenter trial of BoNTA in patients aged >/=21 years who had experienced a stroke >6 months before the initiation of the study. Study 2 was an open-label extension of study 1. Study 3 was a randomized, double-blind, multicenter trial of a specific BoNTA formulation in patients aged >/= 21 years who had experienced a stroke >/=6 weeks before study entry. Patients with a fixed contracture of the studied limb were excluded from participation in studies 1 and 2. Serum samples were obtained from each patient before each BoNTA treatment and at the end of each study. The mouse protection assay (MPA) was used for detection of NAbs to BoNTA in serum.

RESULTS

A total of 235 individual patients with post-stroke spasticity were enrolled in the 3 trials, including 126, 111 (all of whom participated in study 1), and 109 in studies 1, 2, and 3, respectively. Study 1 had an equal (50.0%) distribution of male and female patients (63/63). The distribution of male and female patients was 56 (50.5%) and 55 (49.5%), respectively, in study 2, and 55 (50.5%) and 54 (49.5), respectively, in study 3. The mean (SD) ages of patients in studies 1, 2, and 3 were 61.4 (13.8), 61.5 (14.1), and 58.5 (13.9) years, respectively. The MPA was used for detection of NAbs to BoNTA in the serum samples of 191 patients, including 64 from study 1, 111 from study 2 (55 of these patients were placebo recipients and 56 received their first BoNTA injection in study 1), and 72 (a sample was not obtained for 1 patient who had not received an injection) from study 3. The median number of BoNTA treatments received by these patients was 2 (range, 1-4 treatments) over a period lasting from 12 to 42 weeks. The mean dose of BoNTA was 241 U (range, 100-400 U), with a maximum dose of 960 U in any 1 patient. NAbs to BoNTA were detected in the serum sample of 1/191 (0.5%) patient who had participated in studies 1 and 2. Based on muscle-tone scores (3 and 4 for wrist and fingers, respectively) on a 5-point Ashworth Scale (0 = none to 4 = severe), the patient did not appear to exhibit a clinical response to BoNTA at any time during the studies.

CONCLUSION

Formation of NAbs was rare (1/191) in this group of adults with poststroke spasticity from three 12- to 42-week clinical trials who received >/=1 treatment with a specific BoNTA formulation at doses ranging from 100 to 400 U.

Antibodies Against Botulinum Neurotoxin Type A as a Cause of Treatment Failure After the First Detrusor Injection

Botulinum neurotoxins are increasingly used in treatment for hyperactive detrusor and sphincter function. Although reported results are promising, conditions in some patients are refractory. We report what we believe to be the first urologic case of therapy failure possibly induced by botulinum toxin antibodies after just one injection and discuss treatment alternatives based on experience in other fields.

Antibody-induced failure of botulinum toxin type A therapy in a patient with masseteric hypertrophy

BACKGROUND

With the expanding use of botulinum toxin, much concern about the antibody against botulinum toxin is arising. Unlike neurologic indications such as cervical dystonia, antibody-induced failure of botulinum toxin therapy has never been reported in the cosmetic field.

OBJECTIVE

The objective was to describe a case of an antibody-induced failure of botulinum toxin type A (BTX-A) therapy (BOTOX, Allergan, Inc.) that occurred in a patient with masseteric hypertrophy.

METHODS AND MATERIALS

We present a 20-year-old girl who developed antibody-induced therapy failure after the fourth injection series. Sixty units of toxin was injected at each series and the intertreatment interval was four to five months.

RESULTS

Frontalis test revealed no paresis of muscle after a unilateral injection of BTX-A. Circulating antibodies against BTX-A were detected by indirect enzyme-linked immunosorbent assay and mouse protection assay.

CONCLUSION

This case is unique in that, first, immunoresistance developed in a patient of cosmetic indication where only a small dose of BTX-A was administered and, second, antibodies developed on the so-called new formulation of BOTOX. Our case alerts cosmetic surgeons to the importance of antibody against the botulinum toxin.

Secondary non-response due to antibody formation in a child after three injections of botulinum toxin B into the salivary glands

Botulinum toxin (BTX) offers a new treatment option to reduce drooling in adults and children. Antibody formation against BTX is known to be one reason for clinical secondary non-response to this treatment. This is a case report on the development of secondary non-response to BTX type B (BTX-B) in a 15-year-old male, with bilateral dyskinetic cerebral palsy (Gross Motor Function Classification System Level IV) with additional learning disability* and microcephaly, treated for the indication of drooling. After three successful treatment sessions, the fourth and fifth injections showed no clinical response. This was associated with the presence of antibodies against BTX-B as determined using the mouse diaphragm assay. Thus, formation of neutralizing antibodies against BTX-B appears to be an important issue, not only in patients treated for cervical dystonia but also in children treated for drooling. Subsequent injections with an adequate dose of BTX type A (BTX-A) did not show any clinical response either, although no antibodies to BTX-A were detected. Besides the unanswered questions of dosing and distribution, a second possible explanation could be that BTX-B gave rise to non-neutralizing antibodies that cross-react with BTX-A. The resulting immune complexes could be taken up by phagocytes and, thereby, impede clinical response.

Clinico-immunologic aspects of botulinum toxin type B treatment of cervical dystonia

In this multicenter study of 100 patients with cervical dystonia, we examined the immunogenicity of botulinum toxin type B (BTX-B) and correlated the clinical response with the presence of blocking antibodies (Abs) using a novel mouse protection assay. One-third of the patients who were negative for BTX-B Abs at baseline became positive for BTX-B Abs at last visit. Thus, the high antigenicity of BTX-B limits its long-term efficacy.

Botulinum toxin therapy for cervical dystonia

Cervical dystonia (CD) is the most common form of focal dystonia treated with botulinum toxin (BoNT) injections. BoNT has been shown in numerous clinical trials to correct the abnormal posture and movement and to markedly reduce pain associated with CD. In addition, BoNT has favorably modified the natural history of the disease by preventing contractures and other complications of CD, such as secondary degenerative changes of the cervical spine and associated radiculopathy. In a long-term follow-up of patients treated for up to 20 years, the duration of response appears to be sustained and the risk of immunoresistance due to blocking antibodies is relatively small. This review provides and update on the treatment of CD with BoNT type A (BOTOX, Dysport, Xeomin and BoNT type B (Myobloc, NeuroBloc.

Immunological aspects of Botox, Dysport and Myobloc/NeuroBloc

In some patients treated with botulinum toxin (BT), antibodies are produced in association with certain treatment parameters, patient characteristics and immunological properties of the BT preparation used. Therapeutic BT preparations are comprised of botulinum neurotoxin, non-toxic proteins and excipients. Antibodies formed against botulinum neurotoxin can block BT's biological activity. The antigenicity of a BT preparation depends on the amount of botulinum neurotoxin presented to the immune system. This amount is determined by the specific biological activity, the relationship between the biological activity and the amount of botulinum neurotoxin contained in the preparation. For Botox the specific biological activity is 60 MU-EV/ng neurotoxin, for Dysport 100 MU-EV/ng neurotoxin and for Myobloc/NeuroBloc 5 MU-EV/ng neurotoxin. For Myobloc/NeuroBloc this translates into an antibody-induced therapy failure rate of 44% in patients treated for cervical dystonia, whereas for BT type A preparations this figure is approximately 5%. No obvious differences in antigenicity of BT type A preparations have been detected thus far. For the current formulation of Botox, the rate of antibody-induced therapy failure is reportedly less than 1%. To determine the antigenicity of different BT preparations in more detail, prospective studies on large series of unbiased patients with sensitive and specific BT antibody tests are necessary.

Mapping of the regions on the heavy chain of botulinum neurotoxin A (BoNT/A) recognized by antibodies of cervical dystonia patients with immunoresistance to BoNT/A

The purpose of this work was to map the entire recognition profile of the H chain of botulinum neurotoxin A (BoNT/A) by Abs in sera that have protective anti-BoNT/A Abs by the mouse protection assay (MPA) from cervical dystonia (CD) patients who had been treated with botulinum neurotoxin, serotype A (BOTOX). In previous studies we found that human anti-tetanus neurotoxin (TeNT) Abs cross-react with BoNT/A and BoNT/B. In the present work we devised an assay procedure for measuring specific anti-BoNT/A Abs in human sera by absorbing out or inhibiting the anti-TeNT Abs with TeNT before analyzing the sera for the anti-BoNT/A Abs. The sera were obtained from 28 CD patients who had become unresponsive to treatment with BoNT/A and the sera were found to protect mice against a lethal dose of BoNT/A. For localization of the Ab-binding regions on the H chain we employed a set of sixty, 19-residue synthetic peptides (except for peptide C31 which was 22 residues) that encompassed the entire H chain sequence 449-1296 and overlapped consecutively by five residues. The pattern of Ab recognition varied from patient to patient, but a very limited set of peptides were recognized by most of the patients. These were, in decreasing amounts of Ab binding, peptide N25 (H chain residues 785-803), C9/C10 (967-985/981-999), C31 (1275-1296), C15 (1051-1069), C20 (1121-1139), N16 (659-677), N22 (743-761), and N4 (491-509). But not every serum recognized all these peptides. The finding that the binding profile was not the same for all the patients is consistent with previous observations that immune responses to protein antigens are under genetic control and that the response to each epitope within a protein is under separate genetic control. Except for the region within C9/C10, the other regions either coincided (N16 and C31), or overlapped (N4, N22, N25, C15 and C20), with the recently mapped synaptosomes (snps)-binding regions on the H chain. The molecular and clinical implications of these findings are discussed.

The use of botulinum toxin type-B in the treatment of patients who have become unresponsive to botulinum toxin type-A -- initial experiences

The increasing use of botulinum toxin type-A, especially for focal dystonia and spasticity has highlighted the issue of secondary non-responsiveness. Within the last few years botulinum toxin type-B (Myobloc/Neurobloc) has become commercially available as an alternative to type-A. This paper discusses our initial experience of botulinum toxin type-B in a total of 63 individuals who attended our botulinum clinic. Thirty-six patients had cervical dystonia and a secondary non-response to type-A toxin. Thirteen of these patients (36%) had a reasonable clinical response to Neurobloc and continue to have injections. The other 23 patients either had no response, or a poor response, or had unacceptable side effects and ceased treatment. A small number of people with blepharospasm, hemifacial spasm and foot dystonia also had a disappointing response to injection. Twenty patients with spasticity were also type-A resistant. Seven of these show some continuing response to type-B, without unacceptable side effects. These findings demonstrate that botulinum toxin type-B has a place in the management of patients who have become non-responsive to type-A, but overall the responses to type-B toxin were disappointing.

Botulinum toxin type B de novo therapy of cervical dystonia: frequency of antibody induced therapy failure

Botulinum toxin induced therapy failure type B antibody (BT-B, BT-B-AB) has so far only been reported after previous formation of antibodies against botulinum toxin type A (BT-A, BTA- AB). We wanted to explore the risk of BT-B-AB-induced therapy failure in patients who were exposed to botulinum toxin for the first time. For this purpose we followed nine patients with cervical dystonia receiving BT-B (NeuroBloc/Myo- Bloc, Elan Pharmaceuticals) in a dose of 11435 +/- 2977MU during 4.9 +/- 3.0 injection series. All patients showed a satisfactory initial therapeutic response as documented by a Toronto Western Spasmodic Torticollis Rating Scale score reduction from 17.7 +/- 9.4 to 5.3 +/- 4.8 and an overall subjective improvement of 56.1 +/- 28.3%. Seven patients experienced systemic anticholinergic side effects. Five patients had stable therapeutic responses over subsequent injection series. Four patients experienced complete therapy failure with BT-B-AB titres in excess of 10 mU/ml on the mouse diaphragm assay. Doubling the last effective BT-B dose produced neither therapeutic effects nor side effects. Subsequent applications of botulinum toxin type A produced a continued therapeutic response in one patient and complete therapy failure in the other.Despite the small sample size a frequency of 44 % indicates a high risk for BT-B-AB-induced complete therapy failure. The high amount of neurotoxin administered when NeuroBloc/MyoBloc is used might be a contributory factor. Further prospective comparative studies are necessary to monitor the frequency and time course of BT-B-AB formation.

Longitudinal assessment of the dose consistency of botulinum toxin type A (BOTOX) for cervical dystonia

Botulinum toxin type A (BoNT/A) is the principal therapy for patients with cervical dystonia. Repeated treatments over many years are required in most cases. This retrospective review evaluates the dose of BoNT/A used to treat cervical dystonia and the interval between treatments during a 2-year observation period. Outcomes data were abstracted from the medical records of 172 patients at 3 different sites who had received BoNT/A between January and December 1998. A total of 1059 treatments were assessed. Mean per-treatment doses throughout the 2-year study ranged from 241.80 to 254.07 units. The mean interval between treatments was 108.48 days during the first year of observation and 114.14 days during the second year. These findings indicate that doses of and intervals between BoNT/A treatments for cervical dystonia were consistent throughout 2 years of observation.

Mapping of the antibody-binding regions on the HN-domain (residues 449-859) of botulinum neurotoxin A with antitoxin antibodies from four host species. Full profile of the continuous antigenic regions of the H-chain of botulinum neurotoxin A

Previously, we mapped the antibody (Ab) and T-cell recognition regions on the HC domain (residues 855-1296) of the 848-residue heavy (H) chain of botulinum neurotoxin A (BoNT/A). We have mapped here the HN-domain (residues 449-859) regions that bind protective anti-BoNT/A Abs raised in four different species. We synthesized, purified, and characterized 29 19-residue peptides that spanned the entire HN and overlapped consecutively by 5 residues, and also region L218-231 around the L-chain's substrate-binding site. Human, horse, mouse, and chicken anti-BoNT/A Abs did not bind to the L-peptide but recognized similar HN regions within peptides 519-537/533-551/547-565/561-579 (with slight left- or right-shifts), 743-761, 785-803, and 813-831/827-845 overlap. Recognition of other peptides that bound lower Ab levels showed similarities and also some differences. Peptide 463-481, strongly immunodominant with horse antisera, did not bind human, mouse, and chicken Abs. However, peptide 449-467 bound Abs in these three antisera, and the region may have shifted to the right (peptide 463-481) with horse Abs. The overlap 659-677/673-691 reacted strongly with human Abs whereas with mouse and chicken antisera, only peptide 673-691 showed low reactivity. Horse antisera had no detectable Ab binding to region(s) 659-691. The Ab-recognition regions on the H chain occupy surface locations in BoNT/A three-dimensional structure, but the great part of the surface is not immunogenic. Regions recognized by the protective antisera of the four different species are prime candidates for inclusion in synthetic vaccine designs.

The beneficial antispasticity effect of botulinum toxin type A is maintained after repeated treatment cycles

OBJECTIVE

To study the efficacy, safety, and incidence of BtxA antibody formation with repeated treatments with BtxA in post-stroke upper limb muscle spasticity.

METHODS

The study was a prospective open label trial. Patients with established post-stroke upper limb spasticity received 1000 units of BtxA (Dysport) into five muscles of the affected arm on study entry. Treatment was repeated every 12, 16, or 20 weeks as clinically indicated. Each patient received a total of three treatment cycles. Efficacy of treatment was assessed using the Modified Ashworth Scale. Patients were assessed on study entry and on week 4 and 12 of each treatment cycle for all safety and efficacy parameters. Blood samples for BtxA antibody assay were taken at baseline and on completion of the trial.

RESULTS

Fifty one patients were recruited and 41 of them completed the study. Improvement from the cycle one baseline was observed in all the outcome measures. Mild to moderately severe treatment related adverse events were reported in 24% of cases. There were no serious adverse events. No BtxA antibodies were detected.

CONCLUSION

BtxA at a dose of 1000 units Dysport was efficacious in the symptomatic treatment of post-stroke upper limb spasticity. The study suggests that this effect can be maintained with repeated injections for up to at least three treatment cycles, with duration of effect per cycle of between 12 and 20 weeks. BtxA was safe in the dose used in this study and did not induce the formation of detectable levels of neutralising BtxA antibodies.

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.

Anaphylaxis during surgical and interventional procedures

OBJECTIVE

To describe the current evidence-based knowledge of the causes, diagnostic evaluation, and treatment of patients with anaphylaxis associated with surgical and interventional procedures.

DATA SOURCES

Articles published between 1966 and 2003 were identified in MEDLINE using the keywords anaphylactoid, anaphylaxis, anesthetics, antibiotics, cephalosporins, contrast media, colloids, flow cytometry, hypersensitivity, latex, neuromuscular depolarizing agents, neuromuscular nondepolarizing agents, penicillins, radioallergosorbent test, skin test, and vancomycin. Additional studies were identified from article reference lists.

STUDY SELECTION

Relevant, peer-reviewed original research articles and reviews.

RESULTS

Neuromuscular blocking agents, natural rubber latex, antibiotics, and induction agents are the most common causes of anaphylaxis during surgical and interventional procedures. Colloids, opioids, and radiocontrast media probably account for less than 10% of all reactions. Newer agents implicated in anaphylaxis include isosulphan blue and chlorhexidine. Skin tests are useful for evaluating allergic reactions to anesthetic agents and penicillins and for selecting alternative agents. Skin testing and specific IgE measurements for latex vary in allergen standardization and sensitivity and specificity, respectively. Flow cytometric allergen stimulation tests show promise in differentiating allergic from idiosyncratic ("pseudoallergic") reactions. Drug desensitization has been shown to be useful for penicillin anaphylaxis. Premedication with histamine receptor antagonists and corticosteroids helps prevent or attenuate radiocontrast media reactions.

CONCLUSIONS

Anaphylaxis during surgical and interventional procedures may be difficult to evaluate because of the rapid, successive use of multiple drugs or diagnostic agents. Careful analysis of anesthetic records and diagnostic tests for all the putative agents are necessary to ensure a complete evaluation.

Botulinum toxin in clinical practice

Botulinum toxin, the most potent biological toxin, has become a powerful therapeutic tool for a growing number of clinical applications. This review draws attention to new findings about the mechanism of action of botulinum toxin and briefly reviews some of its most frequent uses, focusing on evidence based data. Double blind, placebo controlled studies, as well as open label clinical trials, provide evidence that, when appropriate targets and doses are selected, botulinum toxin temporarily ameliorates disorders associated with excessive muscle contraction or autonomic dysfunction. When injected not more often than every three months, the risk of blocking antibodies is slight. Long term experience with this agent suggests that it is an effective and safe treatment not only for approved indications but also for an increasing number of off-label indications.

Deciphering antibody properties that lead to potent botulinum neurotoxin neutralization

Monoclonal antibodies (mAbs) have been developed that bind to the toxin binding domain (H(C)) of botulinum toxin type A. These mAbs recognize with high affinity nonoverlapping epitopes on native toxin. The potency of a combination of three of the mAbs is almost 100 times greater than that reported for human polyclonal botulinum immune globulin. Potency appears to result largely from a marked increase in binding affinity for toxin that results when antibodies are combined. Precise epitope, or even domain recognized, seems to be of much less importance. The very high affinity required for toxin neutralization suggests why single mAbs that potently neutralize toxin have not been reported. Such affinities are not typically generated by the immune response.

Complications with the use of botulinum toxin

This article discusses complications with the use of botulinum toxin. The following topics are explored: conditions caused by muscle spasms, resistance to botulinum toxin, cosmetic use of botulinum toxin, complications in treating hyperhidrosis, treatment of migraine headaches, and informed consent.

Ninhydrin sweat test: A simple method for detecting antibodies neutralizing botulinum toxin type A

Approximately 5% of patients with cervical dystonia receiving repeated botulinum neurotoxin A (BoNT/A) injections develop secondary loss of treatment benefit. Currently available tests to directly detect neutralizing BoNT/A antibodies (BoNT/A-AB) are either expensive or time consuming. To establish a simple, clinically useful test for antibody detection, we adapted the ninhydrin sweat test (NST). Eighteen dystonic patients with secondary nonresponse and clinically suspected BoNT/A-AB formation were tested for BoNT/A-AB in the mouse diaphragm test (MDT). In addition, the size of the anhidrotic area was determined by the NST 21 days after an intradermal dose of 10 U Dysport into the hypothenar region of the left palm. In nine patients, positive BoNT-AB titers were found in the MDT. There was a significant correlation between the BoNT/A-AB titers and the anhidrotic area (Spearman's rho = -0.9, P < 0.0001). Both tests provided comparably good results with respect to qualitative antibody detection. In the clinical situation of secondary nonresponse to BoNT/A therapy, the economical NST may be a helpful tool to detect neutralizing BoNT/A-AB.

Pharmacology and immunology of botulinum toxin type A

The utility of botulinum neurotoxins as therapeutic and esthetic agents depends on their ability to inhibit neurotransmitter release from selected neurons, remain localized at the site of injection, and evade the body's immunologic defenses. The clinical correlates of these actions, respectively, are efficacy, safety, and a low rate of antibody formation. These properties have long formed the basis for the use of botulinum toxin type A (BTX-A) in the treatment of movement disorders such as focal dystonias, spasticity, and cerebral palsy and, more recently, in the treatment of glabellar lines--all of which are characterized by excessive muscle activity.

Botulinum toxin type A and other botulinum toxin serotypes: a comparative review of biochemical and pharmacological actions

Botulinum toxin type A is an important therapeutic agent for the treatment of movement and other disorders. As the clinical uses of botulinum toxin type A expand, it is increasingly important to understand the biochemical and pharmacological actions of this toxin, as well as those of other botulinum toxin serotypes (B-G). Botulinum neurotoxin serotypes exhibit differences in neurotoxin complex protein size, percentage of neurotoxin in the activated or nicked form, intracellular protein target, and potency. These properties differ even between preparations that contain the same botulinum toxin serotype due to variations in product formulations. As demonstrated in preclinical and clinical studies, these differences result in a unique combination of efficacy, duration of action, safety, and antigenic potential for each botulinum neurotoxin preparation.

Pharmacology and immunology of botulinum toxin serotypes

Botulinum toxin preparations can provide patients with a therapeutic modality that may improve both their medical condition and quality of life. The mechanism of action of the various botulinum toxin preparations and serotypes is similar: they all block neurotransmitter release. The majority of clinical conditions treated are based upon the targeted temporary chemodenervation of the selected organ. The antinociceptive effects of botulinum toxin type A (BTX-A), based on preclinical studies and clinical experiences in treating movement disorders and other painful conditions, will also be reviewed to illustrate how this compound may act as it alleviates the discomfort associated with various conditions. Chronic therapies with preparations with the lowest amount of neurotoxin protein provide the best chance for long-term therapy by minimizing the potential of the patient to form neutralizing antibodies. Differences in formulations or serotypes impart unique efficacy and safety profiles and thus does not support a simple dose ratio conversion between products.

Botulinum toxin type A: history and current cosmetic use in the upper face

This article reviews the cosmetic use of botulinum toxin in upper face from both the historic and clinical viewpoints. The published literature and our current experience are outlined. Botulinum toxin type A in the upper face has become an extremely poplular cosmetic procedure and is outstandingly safe.

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.

[Treatment of focal dystonia with botulinum toxin A]

Local injections with Botulinum toxin A (BtxA) are safe and effective in the treatment of focal dystonia. In cervical dystonia and blepharospasm, BtxA injections have become the treatment of choice. However, good results have also been reported with oromandibular dystonia, spasmodic dysphonia and writer's cramp. In cervical dystonia, muscles for injection are selected by clinical presentation or in complex forms with EMG guidance. Several studies have shown that 500 units Dysport are safe and effective in the treatment of cervical dystonia. In blepharospasm, injections are performed in the periorbital part of the orbicularis oculi muscle with good results for 12-14 weeks. The most frequently employed starting dose is 120 units Dysport per eye, divided in three periorbital injection sites. In case of levator inhibition, the pretarsal part of the orbicularis oculi muscle should be injected in a lower dose. EMG guidance is not necessary. By contrast, BtxA treatment of spasmodic dysphonia and writer's cramp require EMG-guided injections in order to avoid side-effects. Dose recommendations for the various types of dystonia are given in the text. In up to 5% of patients with dystonia, the development of neutralising antibodies is reported following repetitive injections with BtxA. Patients with antibodies had a shorter interval between injections, more "boosters", a higher dose per 3-month interval, and a higher total dose injected. In case of neutralizing antibodies against the A toxin, the treatment with Botulinum toxin B (Neurobloc) is a possible alternative.

Criteria of evaluation and of interpretation of Sepharose drug IgE-RIA to anaesthetic drugs

The detection of antidrug specific IgE in serum is usually performed by a sandwich-type immunoassay in which the serum IgE is first adsorbed to a reactive phase and subsequently quantified via the binding of an anti-IgE tracer. The preparation of a new drug-reactive phase requires one to establish carefully different steps of validation: 1) criteria of positivity of control sera 2) competitive inhibition assays with the soluble drug, which should include the determination of the inhibition constant rather than estimation of a single inhibition percentage, especially when the assay is performed for the identification of determinants 3) estimation of nonspecific binding of IgE to the solid phase, including hydrophobic binding. The competitive inhibition depends on the concentration of the competitor and of IgE in the test-tube and the concentration of reactive drug bound to the solid phase. We have improved the inhibition assay by performing the Dixon test for calculating the inhibition constant (Ki) of the competitor. The Ki of six different muscle relaxants was determined in 12 patients who experienced an anaphylactic reaction to muscle relaxants. The values ranged between 1.5 nM and 2.5 microM. This confirmed the great heterogeneity of drug IgE cross-reactivity among patients. The Ki value of the incriminated drug was the lowest (affinity, the highest) in eight of the 12 patients. It was better correlated to clinical data than the classical inhibition assay. A hydrophobic environment seemed to be necessary, close to the quaternary ion, to allow IgE binding to the muscle relaxant. By contrast, in tiemonium, a hydroxyl group present at a distance of about 3 A from the quaternary ion may explain why this molecule had a high Ki (microM). In conclusion, it should be recommended, in molecular-recognition studies, that the inhibition constant of the soluble drug and of the related compounds be determined to complement the experiments based only on hapten inhibition assays.

DNA vaccination using the fragment C of botulinum neurotoxin type A provided protective immunity in mice

Botulinum neurotoxin (BoNT) is one of the most toxic substances known to produce severe neuromuscular paralysis. The currently used vaccine is prepared mainly from biohazardous toxins. Thus, we studied an alternative method and demonstrated that DNA immunization provided sufficient protection against botulism in a murine model. A plasmid of pBoNT/A-Hc, which encodes the fragment C gene of type A botulinum neurotoxin, was constructed and fused with an Igkappa leader sequence under the control of a human cytomegalovirus promoter. After 10 cycles of DNA inoculation with this plasmid, mice survived lethal doses of type A botulinum neurotoxin challenges. Immunized mice also elicited cross-protection to the challenges of type E botulinum neurotoxin. This is the first study demonstrating the potential use of DNA vaccination for botulinum neurotoxins.

[Botulinum toxin: mechanism of action]

Inhibitory effect of botulinum toxin on acetylcholine release from the neurons of peripheral nervous system and morphological changes produced in neuro-muscular junction by administration of the toxin are discussed. Other possible mechanisms of action, which can be responsible for the therapeutic effect are presented. Two clinically important problems are discussed: spreading of the toxin from the site of injection, and immunization which is responsible for non-responsiveness in some cases.

Variability of the immunologic and clinical response in dystonic patients immunoresistant to botulinum toxin injections

Immunoresistance (Ab+) to botulinum toxin type A (BTX-A) has been a serious concern since the introduction of BTX-A in the treatment of dystonia and other disorders associated with abnormal muscle contractions. We studied seven patients who developed Ab+ and later reverted to antibody-negative (Ab-) status. These seven patients, six women (mean age, 56 years; range, 41-80 years), with an average duration of dystonia for all patients of 197 months (range, 84-360 months), received a total mean cumulative dose of 1659 units (U) (range, 810-1975 U), with an average dose of 207 U per visit. All of these patients became unresponsive to BTX-A treatment and became Ab+ as determined by mouse bioassay. Their response to BTX-A after they reverted to Ab- was analyzed. The average latency between the initial BTX-A treatment and development of Ab+ was 27 months (range, 1543 months). The average duration between the detection of Ab+ status and subsequent reversal to Ab- status was 30 months (range, 10-78 months). Six of these Ab- patients were reinjected with BTX-A, and all six benefited from repeat injections comparable with their earlier response. Three patients lost their clinical response to subsequent injections and were found to be again Ab+. Two of the five patients who became immunoresistant to BTX-A received botulinum toxin type F (BTX-F) injections and one patient received a single session of BTX-B with improvement in their symptoms. In conclusion, this unique group of patients who were Ab+ and became Ab- responded favorably to repeat BTX-A injections, but some lost the benefit with subsequent injections. These observations suggest that the anamnestic immunologic response to BTX-A can wane, but can be reactivated by repeat BTX-A treatments. The presence of antibodies did not interfere with the response to BTX-F or BTX-B injections, thus confirming the antigenic specificity of various BTX serotypes.