On the absence of interchangeability of botulinum toxin type A drugs
In the Russian Federation, as well as in many countries of the world, several botulinum toxin type A (BTA) drugs are licensed for use as injections; these are biological medicinal products derived from Clostridium botulinum. It is highly important to choose the right drug from the available list or prefer one drug over another, as well as to decide on the interchangeability of drugs or lack thereof. Differences between BTA drugs concern production processes, formulation or composition, quantitative assays to measure biological activity and, consequently, interaction of each of the BTA drugs with target tissues in vivo which was demonstrated in preclinical dose-response trials. Differences also include clinical dosage, potency and duration of action, safety and tolerability. Many of the published trials noted differences in the action of certain BTA drugs depending on experimental and clinical conditions, whereas such differences are not always predictable. Moreover, the drugs vary by the number and quality of clinical trials in which they were tested, as evidenced by the reviewed articles. Designed as solutions for tough clinical situations, BTA drugs are highly efficient biological products with a complex structure and individual formulation. It is extremely important to understand that, and that doses and effects of drugs cannot be interchangeable; each BTA drug should be administered in strict accordance with the manufacturer's recommendations.