Patient-centric dose equivalency pilot study of incobotulinumtoxin a (xeomin) vs. abobotulinumtoxin a (dysport) in the treatment of glabellar frown lines

Aim: Incobotulinumtoxin A (xeomin) has been proposed as an alternative to abobotulinumtoxin A (dysport) and onabotulinumtoxin A (Botox) in the treatment of glabellar frown lines. A recent study is comparing abobotulinumtoxin A and onabotulinumtoxin A revealed equivalent efficacy with a dose conversion ratio of 2.5:1. We sought to establish effectiveness and dosing equivalency of incobotulinumtoxin A vs. abobotulinumtoxin A. Methods: Inclusion criteria for this pilot study included patients of a single surgeon (LAC) who had previously received a constant dose of abobotulinumtoxin A over at least four consecutive treatment sessions for the previous 12 months to achieve an 85-90% elimination of dynamic glabellar frown lines. The primary outcome sought dose comparison between established maintenance abobotulinumtoxin A dosing and incobotulinumtoxin A first-time dosing. A 2:1 conversion (abobotulinumtoxin A: incobotulinumtoxin A) was chosen in most patients. Secondary outcomes were patient-reported onset of effect, physician-assessed effect at 10-12 weeks, pain associated with administration, and patient perceived need for re-treatment at 2 weeks. Results: A total of 32 subjects were included. The mean dose of incobotulinumtoxin A was 17.1 units (± 6.1, the median dose 20 units). The mean dose of abobotulinumtoxin A was 27.6 (± 11.7, the median dose 27.5 units). The mean difference in treatment units was -10.5 (95% confidence interval, P < 0.001). Among 30 patients who reported effect onset, the median was 8.5 days, with a range of 1-14. At 10-12 weeks, muscle paralysis was assessed to be 69.2% (± 27.3), vs. 90.3% (± 1.8) with abobotulinumtoxin A (P < 0.001). The majority of patients rated pain of administration as equal or greater to that of abobotulinumtoxin A (63% and 22%, respectively). Three patients (9%) required re-treatment at 2 weeks with abobotulinumtoxin A due to lack of effective treatment with incobotulinumtoxin A. Abobotulinumtoxin A re-treatment was chosen by the patient. Conclusion: We found incobotulinumtoxin A at 17.1 (± 6.1) units to be less effective than abobotulinumtoxin A at 27.6 (± 11.7) units in the treatment of glabellar frown lines at 10-12 weeks postadministration. Dosing was less predictable than dosing associated with abobotulinumtoxin A treatment. Larger, randomized controlled trials are indicated to further delineate these differences and to clarify whether this difference from previously published incobotulinumtoxin A dosing may have been due to the small sample size.