Chemodenervation, using botulinum neurotoxin-A, prolongs the lasting effects of hyaluronic acid (HA) fillers by reducing muscle activity in the treated area, according to a new study.
Aesthetic physicians have been known to use HA fillers in combination with Botox (Allergan) to temporarily reduce muscle activity and prolong filler life. Turkish researchers used an animal model to more objectively demonstrate the approach.
They injected a small amount of HA filler under rabbits’ skin, in the front of each ear (to mimic the glabellar region in humans). Researchers used HA filler, alone, on one side, and HA filler combined with Botox on the other.
After three months, the researchers compared the amount of filler remaining on the two sides by using MRI scans. The follow-up scans confirmed that Botox slowed filler degradation by 42% compared to the non-Botox side. The difference was both visible on photographs and measurable.
According to the study’s abstract: “Average initial volumes of filler only and filler combined with botulinum neurotoxin type A were 0.61 cm3 on both sides, and there was no difference between initial volumes of the two sides…. At the end of three months, average degraded volumes of filler only and filler combined with botulinum neurotoxin were 0.33 cm3 and 0.19 cm3, respectively, and the degradation difference was significant between the two groups…. End volumes for the filler-only and the filler combined with botulinum neurotoxin sides were 0.28 cm3 and 0.42 cm3, respectively, and end volumes between the two sides were also statistically significant….”