Treatment of glabellar lines with botulinum toxin type A (Speywood Unit): a clinical overview

Azzalure (Galderma) is a newly approved European botulinum neurotoxin type A (BoNT-A) specifically designed for aesthetic usages. It is sourced from Dysport (Ipsen Ltd.), which has a 20-year product consistency and has been used widely for various therapeutic and aesthetic applications. Azzalure and Dysport are collectively referred to as BoNT-A (Speywood Unit; s.U) (or abobotulinumtoxinA in the U.S.) after their biological activity unit, which is unique and not interchangeable with units of other commercial BoNT-A preparations. Azzalure is approved for the treatment of moderate-to-severe glabellar lines, with a total dose of 50 s.U distributed evenly among 5 injection points. To ensure optimal treatment outcomes with BoNT-A (s.U), it is crucial for injectors to adopt proper methods of reconstitution and injection, which can be acquired through training. We review here the method of reconstitution for BoNT-A (s.U), as well as the injection dose, points and techniques for glabellar line treatment. We also review the efficacy and safety results of BoNT-A (s.U) demonstrated in 11 clinical studies, most of which were randomized, double-blind and placebo-controlled. The studies included assessments after single injections as well as after up to 6 repeated treatment sessions. We summarize the clinical efficacy results, which include the responder rate 1 month post-injection, onset of response and duration of action, as well as safety results, which include incidence of treatment-emergent adverse events and specifically eyelid ptosis. The efficacy and safety profiles reported here are unique to BoNT-A (s.U) and cannot be generalized to other BoNT-A products.