Current Evidence on the Unit Equivalence of Different Botulinum Neurotoxin A Formulations and Recommendations for Clinical Practice in Dermatology
Article first published online: 3 NOV 2008
© 2008 by the American Society for Dermatologic Surgery, Inc.
Volume 35, Issue 1, pages 1–8, January 2009
How to Cite
KARSAI, S. and RAULIN, C. (2009), Current Evidence on the Unit Equivalence of Different Botulinum Neurotoxin A Formulations and Recommendations for Clinical Practice in Dermatology. Dermatologic Surgery, 35: 1–8. doi: 10.1111/j.1524-4725.2008.34375.x
- Issue published online: 5 JAN 2009
- Article first published online: 3 NOV 2008
BACKGROUND The unit equivalence between the two main Botulinum neurotoxin A (BoNTA) preparations, Dysport (Ipsen Ltd., Slough, Berkshire, UK) and BOTOX (Allergan Inc., Irvine, CA), is a matter of discussion. The UK assay used to test Dysport is more sensitive than the U.S. assay used for BOTOX, resulting in a different efficacy per unit in both formulations. Ratios ranging from 6:1 to 1:1 can be found in the literature, but the more recently published literature suggests that 1 unit of BOTOX is equivalent to approximately 2 to 4 units of Dysport (ratio 2:1–4:1).
OBJECTIVE Because the number of BoNTA treatments is constantly increasing, these differences warrant a systematic review of published evidence about the unit equivalence of UK and U.S. formulations.
METHODS The review is based on a detailed literature research in all relevant databases (MEDLINE, PubMed, Cochrane Library, specialist textbooks).
RESULTS The present review supports the recent assumption that dose ratios of less than 3:1 (e.g., 2.5:1 or even 2:1) between Dysport and BOTOX are probably more suitable.
CONCLUSIONS The current evidence is still insufficient, and further investigation of lower dose ratios is recommended.