Avaliação da relação entre a resposta clínica à aplicação da toxina botulínica para fins estéticos e a produção de anticorpos antitoxina

Abstract

Background: Botulinum toxin (BTX) is composed of a central neurotoxin associated with several non-toxic accessory proteins (NAPs) and has a wide range of therapeutic applications. In dermatology, it has been employed for the treatment of facial rhytides, and despite its proven efficacy, some individuals either do not respond or lose clinical response over time. One possible explanation is the antigenic potential of the NAPs and excipients present in commercially available formulations; however, this remains a point of contention in the literature. Therefore, the objective of this study was to investigate the association between the absence of clinical response to BTX for aesthetic purposes and the presence of antitoxin antibodies (AATx). Methods: This was a pilot interventional clinical study divided into two phases. It involved the application of AbobotulinumtoxinA, reconstituted in 2 mL of 0.9% saline solution, in 34 participants on Day 0 (initial application) and again on Day 1 (15–21 days after D0). For statistical purposes, the first phase included 32 individuals (16 of each sex), aged 25 to 44 years (mean age: 30 years). Four independent evaluators assessed participants clinically using the Lemperle scale, and inter-rater agreement was measured using the weighted Kappa coefficient. In the second phase, blood samples collected on D0, D1 (15–21 days after D0), and D2 (120 days after D0) were analyzed via ELISA to detect AATx. Due to loss to follow-up, this phase included 31 participants. Hierarchical clustering followed by Fisher’s exact test was used to investigate a possible association between clinical response and antibody levels, with a significance level set at α = 0.05. Results: The clinical assessment tool proved effective, and inter-rater agreement was high. Males received higher doses of BTX than females; however, no significant difference between sexes was observed. One female participant showed no clinical response, but, contrary to expectations, no increase in antitoxin antibody levels was detected. Similarly, some participants exhibited elevated antibody levels without any impact on clinical response. Finally, Fisher’s exact test revealed no significant association between clinical response and AATx levels (p = 0.82). Conclusions: This study did not demonstrate an association between clinical response and AATx levels. The sample size and use of the ELISA method are limitations that may have influenced the results.