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The safety and dose equivalency of PurTox (Mentor) should place the botulinum toxin head-to-head with Botox when it reaches the U.S. market, according to a European physician who has experience using the pure toxin there. The newcomer, PurTox, is said to be equivalent to the universal comparator Botox (onabotulinumtoxinA, Allergan) in terms of dosing, and, therefore, represents a potential future nemesis for Botox and other toxins on the market.
The newcomer, PurTox, is said to be equivalent to the universal comparator Botox (onabotulinumtoxinA, Allergan) in terms of dosing, and, therefore, represents a potential future nemesis for Botox and other toxins on the market.
"Although the safety of leading botulinum toxin products such as Botox and Dysport (abobotulinumtoxinA, Medicis) have not really been a major issue, PurTox may potentially be the safer product and raises the stakes in botulinum toxin therapy," says Gerhard Sattler, M.D., board-certified dermatologic surgeon and director, Rosenpark Clinic, Darmstadt, Germany.
Similar to Botox, PurTox is a refined botulinum type A neurotoxin. The difference is that the company labels its product as a pure toxin, meaning that it does not have any surrounding hemagglutinin protein complex.
Complexing proteins are considered therapeutically superfluous and present a high foreign protein load, which may, in turn, increase the potential for eliciting an immune response. In theory, pure toxins could have less antigenicity and therefore, may be the safer product to use in terms of potential adverse events.
"Although the safety of leading botulinum toxin products such as Botox and Dysport have not really been a major issue, PurTox may potentially be the safer product and raises the stakes in botulinum toxin therapy," Dr. Sattler says.
PurTox recently completed the first of three phase 3 clinical trials for the reduction of glabellar rhytids. According to Dr. Sattler, PurTox is a high-quality product that can achieve excellent clinical outcomes lasting from three to five months and has a good safety profile, similar to that of other leading toxins.
Mentor claims that PurTox has a dose equivalency to Botox (1 unit PurTox:1 unit Botox). Historically, dose equivalency has always been an issue in botulinum toxin therapy, as most products have different dosing regimens (i.e., 2.5 units Dysport:1 unit Botox), adding an element of potential confusion when using different products.
"This dose equivalency was not available for a very long time with products like Dysport; however, with the advent of PurTox, I believe we may have to brace ourselves for the potential windfall of this directly competitive product," Dr. Sattler says.
Battle for top spot
According to Dr. Sattler, many botulinum toxin manufacturers state their product to be superior and claim advantages in regard to longevity of results, speed of onset of clinical effect, as well as a better safety profile. If botulinum toxin products are identical, however, these claims would be unfounded.
"As PurTox has an exact dose equivalency to Botox, it does not really make a difference if one uses one or the other. Any variations in aesthetic or clinical results may be due to other factors such as different injector capabilities, but would not be due to the product itself," Dr. Sattler says.
Although PurTox offers dose equivalency, Dr. Sattler says many physicians may not be quick to switch to a new product, simply because of the decades-long and positive experiences they may have had with more established products such as Botox.