Botulinum toxin type A (BTX-A) formulations such as Botox (Allergan), Dysport (Galderma) and Xeomin (Merz) have moved well beyond their accepted roles as temporary erasers of glabellar lines, forehead rhytides and crow’s feet. Today, they are routinely employed all over the face and neck, and are being investigated for an impressive array of new indications.
New Products in the Pipeline
Although studies have shown few differences in effectiveness among the currently available brands of BTX-A, novel formulations now undergoing clinical trials could offer some new advantages, including increased ease of use, better longevity of results and needle-free delivery.
Topical BTX-A: Though there are several neurotoxin products currently in the FDA pipeline, perhaps none are generating as much excitement as RT001 (Revance). The topical gel, which combines pure BTX-A and a transmission peptide, is currently in Phase 3 clinical trials. “RT001 distributes BTX-A in the mid-dermis via a delivery peptide,” says Catherine P. Winslow, MD, assistant clinical professor at the Indiana University School of Medicine and facial plastic surgeon. “It shows promise for use with problems such as crow’s feet, where the skin is thin and distribution would be relatively effective. It also has applications for treatment of hyperhidrosis.
“It is unlikely to be as effective as injections for treatment in thicker-skinned areas, such as the forehead, or in areas where the muscle is strong, such as between the brows,” she continues. “However, as a weaker but still effective option it appears to be promising for those with needle phobias.”
Revance chief scientific officer Jacob Waugh, MD sees much wider use for RT001. “It behaves just like the intradermally injected BTX-A,” he says. “We thought we would see some differences—slower onset or less duration of action, for instance—but after treating more than 1,000 patients with RT001, tests show it acts just like injected BTX-A. Thickness or skin type seems to play no part in effectiveness. We think our topical treatment will be effective for most indications. Only those targeting deep muscles will require an injection.”
Revance is currently conducting a Phase 3 clinical trial to evaluate a single topical application of RT001 as treatment for moderate to severe crow’s feet. Researchers are employing advanced clinical methods such as electromyography to demonstrate the ability of the topical to penetrate and immobilize targeted muscle tissue. The company is also beginning Phase 2 clinical trials to determine the safety and efficacy of RT001 in the treatment of severe axillary hyperhidrosis.
As practitioners await the approval of this new topical neurotoxin, they are highlighting potential indications and voicing some concerns. Connie Brennan, RN, CPSN, CANS, CPC, director of medical aesthetic education at the Center for Advanced Aesthetics at Life Time Fitness and president/founder of Aesthetic Enhancement Solutions, questions the value of topical BTX-A. “Injections in the face are very precise, allowing exact placement at different depths in the tissue, which makes injected BTX-A a very safe and effective tool,” she says. “It will be interesting to see how the topically applied neurotoxin fares in Phase 3 clinical studies.” She speculates that a safe, effective topical could be delivered with microneedling or ultrasound in some areas.
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