The safety of botulinum neurotoxin type A's intraarticular application in experimental animals

Ana Dugonjić Okroša; Victor Ricardo Manuel Muñoz-Lora; Ivica Matak; Lidija Bach-Rojecky; Mikhail Kalinichev; Zdravko Lacković

doi:10.1016/j.toxcx.2023.100155

The safety of botulinum neurotoxin type A's intraarticular application in experimental animals

Toxicon X. 2023 Mar 31:18:100155. doi: 10.1016/j.toxcx.2023.100155. eCollection 2023 Jun.

Authors

Ana Dugonjić Okroša¹, Victor Ricardo Manuel Muñoz-Lora^{2

3}, Ivica Matak², Lidija Bach-Rojecky¹, Mikhail Kalinichev⁴, Zdravko Lacković²

Affiliations

¹ Department of Pharmacology, University of Zagreb Faculty of Pharmacy and Biochemistry, Croatia.
² Laboratory of Molecular Neuropharmacology, Department of Pharmacology, University of Zagreb School of Medicine, Croatia.
³ Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Brazil.
⁴ Ipsen Innovation, 91940 Les Ulis, France.

Abstract

In vivo studies of botulinum neurotoxin type A (BoNT-A) enabled characterization of its activity in the nociceptive sensory system separate from its preferred action in motor and autonomic nerve terminals. However, in the recent rodent studies of arthritic pain which employed high intra-articular (i.a.) doses (expressed as a total number of units (U) per animal or U/kg), possible systemic effects have not been conclusively excluded. Herein we assessed the effect of two pharmaceutical preparations, abobotulinumtoxinA (aboBoNT-A, 10, 20, and 40 U/kg corresponding to 0.05, 0.11, and 0.22 ng/kg neurotoxin) and onabotulinumtoxinA (onaBoNT-A, 10 and 20 U/kg corresponding to 0.09 and 0.18 ng/kg, respectively) injected into the rat knee, on safety-relevant readouts: digit abduction, motor performance and weight gain during 14 days post-treatment. The i. a. toxin produced dose-dependent impairment of the toe spreading reflex and rotarod performance, which was moderate and transient after 10 U/kg onaBoNT-A and ≤20 U/kg aboBoNT-A doses, and severe and long-lasting (examined up to 14 days) after ≥20 U/kg of onaBoNT-A and 40 U/kg aboBoNT-A. In addition, lower toxin doses prevented the normal weight gain compared to controls, while higher doses induced marked weight loss (≥20 U/kg of onaBoNT-A and 40 U/kg aboBoNT-A). Commonly employed BoNT-A formulations, depending on the doses, cause local relaxation of the surrounding muscles and systemic adverse effects in rats. Thus, to evade possible toxin unwanted local or systemic spread, careful dosing and motor testing should be mandatory in preclinical behavioral studies, irrespective of the sites and doses of toxin application.

Keywords: Motor effects; Rats; Systemic spread; abobotulinumtoxinA; onabotulinumtoxinA.