“I am interested in exploring botulinum toxin injections for my unwanted facial wrinkles. What are the differences between brands?”
There are currently three products available. Onabotulinum toxin (“Botox”), Abobotulinum toxin (“Dysport”), and Incabotulinum toxin (“Xeomin”). Each product has a good safety profile and all can lead to excellent outcomes. The manufacturers of each product have spent millions of dollars on research, development and marketing. The biggest difference between products that has been touted by the manufacturers has been the size of their unique, proprietary botulinum toxin product.
The active protein of all 3 products is a 150 kilodalton protein. This protein, after it is injected, binds to nerves and prevents them from communicating with the muscle they innervate. This effectively prevents that part of the muscle from contracting. If enough nerve axons get inactivated, the muscles cannot contract forcefully. In facial muscles, the reduced ability to forcefully contract causes the overlying skin to appear smoother with less wrinkles.
Each active protein is surrounded by a protective coating of additional proteins called NAPs (neurotoxin associated proteins). Botox has the biggest coating, Dysport has the second biggest and Xeomin has no coating at all, just the active botulinum protein.
The two factors that were felt to be affected by the overall size of the final product were the tendency of the botulinum product to diffuse through tissue and the susceptibility of the product to becoming inactivated due to our bodies developing antibodies against the protein (thereby negating its ability to remove wrinkles).
Thus, Botox (which is the biggest product) was felt by some to have less risk of diffusing and was touted to be safer – less chance of causing eyebrow drop or eyelid drop, etc. It was also criticized at having a higher risk of causing an antibody/immune response that could make it less effective than its competitors. Xeomin (which has no associated NAPs) would be considered higher risk of diffusion but less risk of developing immunity to its effects.
Studies that looked into these issues, however, found mixed results. Unfortunately, in some cases, the favorability of a particular product’s performance depended on the pharmaceutical company sponsor of the study.
Recently, it has been shown that NAPs associated with the botulinum products require an acidic Ph in order to remain attached to the botulinum toxin. When the products are reconstituted (“mixed”) with saline before they are injected, the NAPs all fall off!
It will be interesting to see how the manufactures explain the differences between the products. It may be, that there are no significant differences between products! We feel that the choice between which product to use should be based primarily on cost and that is what we tell our clients.