Neurotoxin Update: Botox and more

At the symposium "Perfecting the Art of Facial Rejuvenation", which was held this weekend, there was some updated neurotoxin information presented. Botox has been around since 1989, without much competition. Botox is botulinum toxin type A and the only approved alternative has been Myoblock, which is Botulinum toxin type B. Myoblock has a significantly greater tendency to spread to distant body sites when compared to Botox. People who were being treated with Myoblock for increased hand sweating reported experienced dry mouth, a sign of systemic toxin spread. Myoblock was specifically approved for use in the muscles of the neck, and apparently most of the small number of reported neurotoxin deaths in children were due to Myoblock administration.

Now the Allergan monopoly on Botulinum toxin A product is about to be broken with the imminent release of Reloxin, which is also a type A toxin and has been used in Europe, under the name Dysport, since 1991. Although both Botox and Reloxin use the same toxin, they are not completely identical, due to different manufacturing processes. The units will not be the same, and there is some ongoing discussion about what the equivalent doses will be. The current best guess is that one unit of Botox will equal 3 units of Reloxin. Reloxin also appears to diffuse more widely than Botox, but not nearly as widely as Myoblock. This diffusion will be a definite advantage in certain situations such as the treatment of increased sweating (hyperhidrosis) where wider diffusion may enable the use of less product.
Increased diffusion of the product can be a problem where there is an effect on muscles in which weakness is undesireable. This is uncommonly seen as eyelid droop with Botox. Reports from people who have participated in the US studies on Reloxin report that there this has not been a problem with this product.
There will be other similar products that will follow shortly. Competition will be good for the consumer since there will be more choices and the rapid product price rise will almost certainly slow.

Gerald N. Bock MD
California Skin & Laser Center
Stockton & Lodi, CA