Beyond Botox

Y RACHEL HERSCHENFELD, M.D. - DERMATOLOGIST

Beauty writing is not known for its critical appraisals of current products and procedures. It's always possible to find a glowing review of the latest, greatest trend; it's far harder to find balanced discussions of their pros and cons. Even tried and true procedures have drawbacks and need improvement. Case in point: Botox. The first injectable muscle relaxer approved by the FDA for the treatment of facial lines and wrinkles is the most common non-invasive cosmetic procedure performed in the United States, with more than 4.6 million Botox procedures completed in 2007 (data from the American Society of Plastic Surgeons). Botox is safe, effective and relatively easy to administer (although it takes practice to perfect injection techniques), and it is widely available. However, it is not a perfect treatment (close, but just not quite). Anyone who has been treated with Botox knows that it is administered through a series of tiny injections and takes several days and sometimes up to two weeks to see the effects. Botox also doesn't last forever -- in fact, a typical treatment lasts for three to four months before another treatment is necessary to maintain an improved appearance. Moreover, there are some patients who don't respond well to Botox and don't see much improvement.
Despite these drawbacks, Botox has been a wildly successful product. This success has spurred the development of many potential competitors, some of which may offer advantages over Botox. Manufactured by Allergan, Botox is one of several brands of botulinum toxin subtype A, which all work by temporarily interrupting communication between nerves and muscles, thereby leading to relaxation of wrinkles that are caused by repetitive motions. So far, the only other botulinum toxin available in the U.S. is Myobloc, which contains a slightly different form of this medication, called subtype B. Although Myobloc can work more quickly after it is injected, its effects don't last as long as Botox, so it is not widely used for cosmetic treatments.
Other brands of subtype A are in the works. Reloxin is already available in Europe, where it is known as Dysport. Reloxin may turn out to have some advantages over Botox: It may act more quickly, and in some cases its effects may last longer. However, Reloxin may spread out more after injection. This could increase certain side effects, such as drooping (known as ptosis) of the eyebrows if it is used on the forehead. Spreading out more may prove to be an advantage in other situations, such as treating crow's feet around the eyes, or in treating underarm sweating, which can require more than 15 injections on each side. At least two other injectable botulinum toxins are being studied. Xeomin, which is available in Germany, may be less likely than Botox to cause immune reactions that can lead patients to become resistant to the effects of botulinum toxins. However, because this hasn't been a common problem among patients treated with Botox for cosmetic purposes, it is not clear whether this represents a real advantage. PurTox, another type A botulinum toxin, is currently undergoing trials for treatment of frown lines as well as for other medical uses.
Perhaps most intriguing is a topical form of botulinum toxin type A under development by Revance Therapeutics, Inc. Scientists here have developed a gel which transports the active molecule across the skin and into muscles where it has its effect. Preliminary studies have shown that the gel can treat wrinkles around the eye as well as excess axillary sweating. Because it may be more difficult to precisely target a cream compared with an injectable medication, this product may turn out to be more useful for a larger area, such as excessive sweating.