Recently, the Food and Drug Administration (FDA) approved Dysport, the first new botulinum toxin for wrinkles and muscle spasticity since cosmetic Botox was introduced in 2002. Like Botox, this latest wrinkle fighter is a modified version of botulinum toxin A and inhibits facial muscle contractions that over time lead to forehead lines, frown lines and crows feet. My practice was an investigator in the clinical trial that led to the FDA approval, and we found that Dysport was extremely effective in reducing frown lines between the eyebrows. Our combined results in treating over 1200 patients showed that Dysport injections would reduce lines and furrows between the eyebrows within 7 days. Side effects included injection site reactions, such as bruising or injection misplacement causing drooping of the eyebrow or eyelid, but they were infrequent and resolved within a few weeks. These side effects decreased significantly as the physicians gained more experience in placing the injections. More information on this multicenter study can be found here.
Our study showed that Dysport was effective in eliminating wrinkles, but it is still unclear whether Dysport will be an improvement over Botox or just a healthy competitor. In theory, Dysport should attack wrinkles faster because it has fewer proteins surrounding the toxin. It should also stimulate a weaker immune response to break down the toxin, and thus last longer. Karsai and colleagues tested this by injecting one side of the forehead with Botox and the other side with Dypsort. Both injections suppressed muscle activity 2 weeks after injection, but Dypsort showed statistically greater suppression beginning 10 weeks after injection. On the other hand, Lowe and colleagues found that Botox was longer lasting when injected into the muscles between the eyebrows. These studies used slightly different concentrations of Dysport, which may explain the opposite results. As Dysport gains more use in the US market in the coming months, the optimum treatment techniques and their relative effectiveness compared to Botox will be further clarified.
Despite years of safe use in Europe, the FDA was cautious to approve Dysport in the U.S. after concerns were raised by Public Citizen, a consumer advocacy group, over potentially serious side effects of botulinum toxin injections. Public Citizen urged the FDA to investigate certain rare cases where the botulinum toxin may have spread beyond the injection site to other parts of the body, paralyzing or weakening the muscles used for breathing and swallowing, which could be potentially fatal. After investigating these cases, the FDA found that these adverse events occurred primarily in pediatric populations after high dose injections to treat muscle spasticity due to cerebral palsy, and in adult populations being treated for spasticity or cervical dystonia. It is important to realize that none of these events occurred as a result of the much lower doses of botulinum toxin injected for cosmetic reasons, or the slightly higher doses injected into the underarms for excessive sweating. Still, Dysport, and likely all other botulinum toxins in the future will carry a warning on the box about these risks and the FDA will continue to monitor any adverse events due to migration. Patients can reduce their risks of any adverse events by seeking treatments from highly skilled dermatologists or plastic surgeons and making sure they are treated with Botox or Dysport, the only FDA approved botulinum toxin treatments.
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