Botulinum toxin preparations: areas for improvement and issues of standardisation

Abstract

Scientific relevance. Botulinum toxin preparations are a good example of using a deadly toxin as a unique therapeutic agent. However, there are many unresolved issues related to biotechnology, biological activity, interchangeability, and standardisation of botulinum toxin preparations. Aim. To review current opportunities for improving therapeutic botulinum toxin preparations.Discussion. This review covers botulinum toxin type A preparations and unresolved issues related to them. In the absence of international non-proprietary names recommended by the World Health Organisation or by the Board of the Eurasian Economic Commission, domestic and imported botulinum toxin type A preparations approved in Russia have only similarity-based grouping names. In addition, manufacturers name botulinum toxin preparations at their discretion. Therefore, classifying these preparations under a common nomenclature is essential for clear identification, adequate selection, and correct prescription. Several studies have shown significant variability across botulinum toxin type A preparations. Due to the identified differences in qualitative and quantitative characteristics, botulinum toxin type A preparations cannot be considered similar, which raises the issue of their interchangeability and bioequivalence. To resolve this issue, a unified classification and naming system for botulinum toxin preparations should be established and documented in regulatory standards. According to the literature, manufacturers of botulinum toxin preparations use in-house reference standards. Hence, the same activity unit resulting from toxicity and efficacy studies may express a different protein load for each botulinum toxin preparation. Keeping that in mind, the authors discuss the development of a single international potency standard for existing and pipeline botulinum toxin type A preparations. Conclusions. The article describes novel pharmaceutical compositions containing botulinum toxin, including those in late development. Summarised data from clinical studies on the safety, efficacy, and cost-effectiveness of botulinum toxin type A preparations can guide prescribing decisions.

Keywords

• botulinum toxin
• biological activity of botulinum toxin preparations
• bioequivalence
• biosimilars
• international standards