Botox and Dysport / Azzalure are different molecular formulations of Botulinum Toxin type A. Both have a long (more than 20 years) of established medical use. It was already known that one unit of Botox is not equivalent to 1 unit of Dysport /Azzalure. In Europe the recommendation is to use 2.5 units of Dysport / Azzalure for every 1 unit of Botox. But there has been very little actual clinical research to substantiate this recommendation.
A study of 62 patients in 2006 showed that both treatments were effective in treating wrinkles. However it showed that Botox was better in terms of wrinkle improvement and the duration of effect at 16 weeks than Dysport for forehead wrinkles when the ratio of Botox to Dysport/Azzalure was 1:2.5. The authors said that this study was financially supported by Allergan, the makers of Botox.
However, another study was done in 2007 on 26 people. This time a 1:3 ratio of Botox to Dysport/Azzalure was used so unfortunately it is not directly comparable with the 2006 study. However, this study showed that Dysport/Azzalure was superior to Botox with better duration of effect at 20 weeks after injection. The authors said that this study did not receive financial backing from any of the manufacturers. This study also included electrical measurements of muscle activity as well as digital photographic appraisals done by an independent panel of 3 examiners who assessed with forehead wrinkles of the people in the study.
The conclusions that can be drawn from these studies is that there is no clear best type of Botulinum toxin for cosmetic use. The efficacy of both products in terms of their cosmetic effects is well proven as is their safety record. The duration of action depends to a large extent on how many units are administered. If 3 units of Dysport/Azzalure are used for every one unit of Botox, then the research suggests a slightly longer duration of effect than Botox, and the opposite seems to be true when the recommended 2.5:1 ratio is used.
In terms of other aspects of patient satisfaction, particularly the rapidity of onset of effect and relative incidence of side effects there is no research to guide decisions. Median time to onset of effect is from day 3 for both products and reaches maximal effect at day 30.
Dr. O. Mark Aszkenasy MRCP(UK) Medical Cosmetic Specialist Medical Director, Your Beautiful Skin Ltd http://www.yourbeautifulskin.co.uk
Dr. Aszkenasy is a fully registered medical doctor (GMC 2559874) who specialises in medical cosmetic treatments.