Botox versus Dysport for “crow’s feet” - is one better?

   It’s becoming a crowded world for injectable wrinkle relaxers; first there was Botox, then more recently Dysport, and soon the newly approved competitor Xeomin. It was a simpler world when it was just Botox, as when Xerox was the only copier, Kleenex the default brand for facial tissue, and Clorox the go-to brand of bleach. On the one hand, all of the wrinkle relaxers work the same way, using highly purified versions of the toxin molecule that in very much larger doses causes botulism. When injected into hyperactive facial muscles, the wrinkles are smoothed out. But with several versions of these products now available, is there truly any difference? One new study suggests that Dysport may actually perform better for crow’s feet.
   Comparing the different products has its challenges, among which is figuring out what equivalent doses are. It’s not like with generic drugs, where it is the same thing once it is off-patent.  Botulinum toxin type A is a naturally occurring combination of molecules called a molecular complex.  So the differences are how these molecules are arranged. It functions somewhat like a Trojan horse, with the active part hidden inside. That is why it takes a few days for the effect to appear after injection; the “horse” has to open up and let the toxin molecule out. The newest product, Xeomin, has removed the “horse” already, and Dysport has sort of unlocked the door, so Dysport may take effect a bit faster.
   There are few studies comparing  Botox and Dysport directly however, so this recent one adds important information. A group of patients received Botox (10 units) on one side of the face and Dysport (30 units) on the other.* Unlike treating the area between the eyebrows, the crow’s feet area is separated enough that there is no crossover effect between the two products. Independent evaluation demonstrated a significantly better improvement in wrinkles on the Dysport side, and 2 out of 3 patients felt the result was better on that side. One possible reason for this is due to a quicker release of the active part of the molecular complex with Dysport, resulting in more spread of effect, which some have characterized as a “softer” look.
   There will remain debate about which products works best in which areas, and Xeomin will certainly add to that. What is most important is the experience and judgment of the injector.
*Botox and Dysport are measured in different units so they are not equivalent, rather like Fahrenheit vs. Celsius for temperature.