Fields of effects of 2 commercial preparations of botulinum toxin type A at equal labeled unit doses: a double-blind randomized trial.

Importance: This article provides new data on a controversial issue, the influence of doses on the diffusion characteristics of 2 botulinum toxins type A. OBJECTIVE To assess the fields of effect of abobotulinumtoxinA and onabotulinumtoxinA at the same labeled unit dose (1:1 U) comparing sweat gland and muscle activity.

Design, Setting, And Participants: A prospective, single-center, randomized, double-blind study was conducted at the Brazilian Center for Studies in Dermatology in Porto Alegre, Brazil. The participants included 19 women.

Interventions: Each patient received 2 U of abobotulinumtoxinA on one side of the forehead and 2 U of onabotulinumtoxinA on the other side.

Main Outcomes And Measures: Horizontal and vertical diameter and area of the fields of anhidrotic effect, the amplitude of evoked compound muscle action potentials, and the 4-point validated Wrinkle Severity Scale were assessed at 28 days.

Results: The horizontal and vertical diameters of the fields of effect and the areas were significantly larger for onabotulinumtoxinA than those obtained for abobotulinumtoxinA. There were no significant differences between the products in the Wrinkle Severity Scale scores and Evoked Compound Muscle Action Potentials. OnabotulinumtoxinA had significantly more diffusion than abobotulinumtoxinA when isovolumetric injections of the same labeled unit dose of the products were injected. CONCLUSIONS AND RELEVANCE Although many studies state that diffusion is product dependent and abobotulinumtoxinA diffuses more than onabotulinumtoxinA, findings from the present study confirm that diffusion is dose dependent and the more potent dose tested diffuses more. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01732809.