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

BACKGROUND

Different diffusion of different botulinum toxin type A (BoNTA) preparations may account for differences in outcomes in cosmetic clinical practice.

OBJECTIVES

A double-blind, randomized, self-controlled study was performed to evaluate the diffusion characteristics of onabotulinumtoxinA and a Chinese type A botulinum toxin (CBTX-A).

MATERIALS AND METHODS

Healthy volunteers (N = 20) were recruited to receive a 0.05-mL (2 U) injection of BoTNA at four forehead sites (medial forehead (subcutaneous (SC)) and temporal forehead (intradermal (ID))). On day 14, the Minor's iodine starch test was performed and photographs were taken for calculating the area and dimensions of anhydrotic area.

RESULTS

When BoNTAs were different, the anhidrosis ID area was significantly greater with CBTX-A than onabotulinumtoxinA, the vertical dimension was significantly longer with CBTX-A ID than onabotulinumtoxinA ID and the horizontal dimension was significantly greater with CBTX-A ID than onabotulinumtoxinA ID. The area of anhidrosis SC was significantly greater with CBTX-A than onabotulinumtoxinA. When injection depths were different, the mean horizontal dimension was significantly greater with onabotulinumtoxinA SC than ID. Comparing the dimension of the same BoNTA and injection method, the vertical dimension was significantly greater than the horizontal dimension.

CONCLUSION

OnabotulinumtoxinA diffuses less than CBTX-A. ID injection technique may result in less diffusion than SC.