Diffusion of two botulinum toxins type A on the forehead: double-blinded, randomized, controlled study.

Area of Science:

• Cosmetic dermatology
• Neuromodulation
• Pharmacodynamics

Background:

• Variations in botulinum toxin type A (BoNTA) diffusion can influence cosmetic treatment outcomes.
• Understanding diffusion characteristics is crucial for optimizing clinical application.

Purpose of the Study:

• To compare the diffusion characteristics of onabotulinumtoxinA and Chinese type A botulinum toxin (CBTX-A).
• To evaluate the impact of injection technique (intradermal vs. subcutaneous) on BoNTA diffusion.

Main Methods:

• A double-blind, randomized, self-controlled study involving 20 healthy volunteers.
• Injections of 0.05 mL (2 U) of BoNTA were administered at medial forehead (subcutaneous) and temporal forehead (intradermal) sites.
• Diffusion was assessed on day 14 using the Minor's iodine starch test to measure the anhydrotic area and dimensions.

Main Results:

• CBTX-A exhibited significantly greater anhidrosis area and dimensions (vertical and horizontal) compared to onabotulinumtoxinA for intradermal injections.
• Subcutaneous injections of CBTX-A resulted in a larger anhidrosis area than onabotulinumtoxinA.
• OnabotulinumtoxinA showed greater horizontal diffusion with subcutaneous compared to intradermal injections.

Conclusions:

• OnabotulinumtoxinA diffuses less extensively than CBTX-A.
• Intradermal injection technique appears to limit diffusion more than subcutaneous injection.