Botulinum toxin type-A preparations are not the same medications - clinical studies (Part 2).

The growing number of Botulinum neurotoxin type A (BoNT/A) preparations on the market has resulted in a search for pharmacological, clinical and pharmacoeconomic differences. Patients are occasionally switched from one botulinum toxin formulation to another. The aim of this paper was to review studies that have made direct comparisons of the three major BoNT/A preparations presently on the market: ona-, abo- and incobotulinumtoxinA. We also review the single medication Class I pivotal and occasionally Class II-IV studies, as well as recommendations and guidelines to show how effective doses have been adopted in well-established indications such as blepharospasm, hemifacial spasm, cervical dystonia and adult spasticity. Neither direct head-to-head studies nor single medication studies between all preparations allow the formation of universal conversion ratios. All preparations should be treated as distinct medications with respect to their summary of product characteristics when used in everyday practice.