Biotherapeutic medicines: use of botulinum toxins in the era of biosimilars

Introduction: Botulinum toxins are biotherapeutic drugs with great applications in the field of neurology such as headache and abnormal movements. Due to the medical importance and the increase in therapeutic indications of botulinum toxin, this article aims to clarify the basic terminology regarding the nature of this drug, the structural differences with conventional drugs and important aspects in relation to its biological potency and immunogenicity in order to understand the potential differences between the available toxins and conceptualize regarding the non-interchangeability or substitution of one toxin for another.Materials and methods: non-systematic review as recommended in the Scale for the Verification of Narrative Review Articles (SANRA).Conclusions: biological drugs are not interchangeable with each other, even if they demonstrate bioequivalence. They do not meet the FDA's definition of a biosimilar. They cannot be evaluated as interchangeable generic drugs because they are biologics. There are no head-to-head comparative studies. They are different due to the individual manufacturing process.