Primary resistance of human patients to botulinum neurotoxins A and B

Functional Polymorphism in the ADRB3 Gene, Encoding the Beta-3 Adrenergic Receptor, and Response to Intra-Detrusor Injection of Botulinum Toxin-A in Women with Overactive Bladder

BACKGROUND

There are reports suggesting an association between the rs4994 polymorphism in the ADRB3 gene encoding the beta-3 adrenergic receptor and OAB risk in females. The injection of botulinum toxin-A into the bladder wall is recommended as a possible treatment for OAB patients in whom first-line therapies have failed. The aim of our study was to analyze the possible association between the ADRB3:rs4994 polymorphism and the patient-perceived response to a single intra-detrusor injection of botulinum toxin-A in Polish women with overactive bladder.

METHODS

The study group consisted of 115 consecutive female patients with OAB. The response to botulinum toxin-A was evaluated at three months after injection, as absolute or relative reductions in OAB symptoms or in scores from questionnaires ICIQ-OAB (parts A and B) and ICIQ-LUTS-QoL (parts A and B). ADRB3:rs4994 variants were identified by the sequencing of genomic DNA extracted from buccal swabs.

RESULTS

There were no statistically significant differences between ADRB3:rs4994 [T];[T] homozygotes and [T];[C]+[C];[C] subjects for absolute or relative reductions in symptoms or in scores from all four questionnaire parts at three months after the injection of botulinum toxin-A.

CONCLUSIONS

Our results do not support the hypothesis that ADRB3:rs4994 polymorphism is associated with the response to the intra-detrusor injection of botulinum toxin-A in Polish females with overactive bladder.

Long-term treatment of blepharospasm with botulinum toxin A: a service-based study over a 16-year follow-up in southern China

OBJECTIVE

To elucidate the effect of long-term treatment with botulinum toxin A (BTX-A) for blepharospasm. Prevalence data and clinical features in southern China and influencing factors for selecting BTX-A treatment were explored.

METHODS

We collected data retrospectively from 338 consecutive patients diagnosed with blepharospasm over 16 years to assess prevalence data and clinical features. Thereafter, all patients were classified into BTX-A (n = 135) or non-BTX-A (n = 203) treatment groups according to the patients' requests in order to explore the factors influencing whether BTX-A treatment was chosen. Furthermore, dynamic follow-up data were analyzed to evaluate the long-term efficacy in the BTX-A group.

RESULTS

The prevalence was 23.3 per million, with an onset age of 50.3 ± 12.3 years and a female:male ratio of 2.4:1; the most common symptom was excessive blinking (91.2%). The symptom severity and psychological assessment scores were significantly decreased by treatment with BTX-A (p < 0.01), and there was no significant difference in response duration with the prolongation of BTX-A injections. Adverse events occurred 52 times (5.0%) among 1038 injections. The symptom severity and psychological assessment scores and the occurrence of eye-opening difficulty were higher, and medical expenses and the symptom tolerability rate were lower in the BTX-A group than in the non-BTX-A group (p < 0.05).

CONCLUSION

The onset age was earlier than that in Western countries. However, starting BTX-A treatment early is justified, even though a higher dosage was needed to maintain reliable long-term efficacy. Additionally, symptom severity and medical expenses are the primary factors affecting whether patients select BTX-A treatment.

Immunogenicity Associated with Botulinum Toxin Treatment

Botulinum toxin (BoNT) has been used for the treatment of a variety of neurologic, medical and cosmetic conditions. Two serotypes, type A (BoNT-A) and type B (BoNT-B), are currently in clinical use. While considered safe and effective, their use has been rarely complicated by the development of antibodies that reduce or negate their therapeutic effect. The presence of antibodies has been attributed to shorter dosing intervals (and booster injections), higher doses per injection cycle, and higher amounts of antigenic protein. Other factors contributing to the immunogenicity of BoNT include properties of each serotype, such as formulation, manufacturing, and storage of the toxin. Some newer formulations with purified core neurotoxin devoid of accessory proteins may have lower overall immunogenicity. Several assays are available for the detection of antibodies, including both structural assays such as ELISA and mouse-based bioassays, but there is no consistent correlation between these antibodies and clinical response. Prevention and treatment of antibody-associated non-responsiveness is challenging and primarily involves the use of less immunogenic formulations of BoNT, waiting for the spontaneous disappearance of the neutralizing antibody, and switching to an immunologically alternate type of BoNT.

The whole truth about botulinum toxin - a review

Treatment with botulinum toxin is widely viewed as safe, effective and largely devoid of serious side effects. There are two classes of Botox-related adverse events – transient and benign events, and potentially serious events. The aim of this study was to provide an overview of Botox-related side effects and advise potential management and preventive strategies. Benign side effects are well-localized, reversible and self-limited complications which develop within a few days of the injection, and they usually disappear without any treatment. The aesthetic and functional adverse effects are associated with different muscle responses to botulinum toxin or with misplacement of botulinum toxin. The serious events are sequelae due to the systemic spread of toxin leading to botulism.