Field effect of two commercial preparations of botulinum toxin type A: a prospective, double-blind, randomized clinical trial.

Background: The dose equivalence of commonly used commercial preparations of botulinum toxin type A, Dysport (abotulinumtoxinA [ABO] 500 U, Ipsen Biopharm Limited, Wrexham, United Kingdom) and Botox (onabotulinumtoxinA [ONA] 100 U, Allergan, Irvine, CA), remains unclear.

Objective: We sought to evaluate the field effect for ABO and ONA at dose equivalences of 2.5:1.0 U and 2.0:1.0 U, in both muscular and sweat gland activity.

Methods: In all, 59 female patients with forehead wrinkles were enrolled. Patients were randomized for dose equivalence between ABO and ONA, group A (2.0:1.0 U, ABO:ONA) or group B (2.5:1.0 U, ABO:ONA) administered in the frontalis muscles. Clinical assessment, Minor test, and electromyography evaluations were performed at baseline, 28 days, and 112 days.

Results: In group B, the field of anhidrotic effect of ABO showed a greater area and larger horizontal diameter than ONA at 28 and 112 days. At maximum frontalis muscle activity (day 112) patients receiving ABO demonstrated greater improvement based on the Wrinkle Severity Scale. No differences were found in frontalis muscle activity at rest between groups A and B based on results of Wrinkle Severity Scale, electromyography, and interindividual variability data at 28 and 112 days.

Limitations: Currently, there are no objective measurements other than electromyography to evaluate the field effect of botulinum toxin type A in muscles.

Conclusion: At a dose equivalence of 2.0:1.0 U (ABO:ONA), similar field effects were found for both muscle and sweat gland activity. At a higher dose equivalence of 2.5:1.0 U (ABO:ONA), injections of ABO showed greater area and larger horizontal diameter in field of anhidrotic effect at 28 and 112 days than ONA.