NEUROLOGY AND PRECLINICAL NEUROLOGICAL STUDIES- SHORT COMMUNICATION Botulinum toxin therapy of cervical dystonia: comparing onabotulinumtoxinA (Botox) and incobotulinumtoxinA

Abstract Several botulinum toxin (BT) drugs are licensed for the treatment of cervical dystonia (CD). We wanted to compare the efficacy and the potency labelling of incobotulinumtoxinA (Xeomin) and onabotulinumtoxinA (Botox) by analysing the duration of their therapeutic effect in a cross-over study. For this we studied 40 CD patients (26 females, 14 males, age at therapy onset 52.6 ± 12.0 years, duration of dystonia at therapy onset 10.0 ± 9.2 years, Tsui score 9.1 ± 3.9) who first received Botox and then Xeomin for at least 4 injection series each. BT doses were exchanged based on a 1:1 conversion ratio. Altogether 1,101 treatment cycles were evaluated. For each patient 27.5 ± 13.1 treatment cycles were recorded. Patients received 18.4 ± 12.4 treatment cycles with Botox and 9.2 ± 4.5 with Xeomin. The treatment duration (TD) throughout the treatment course was 11.3 ± 1.0 weeks (Botox 11.2 ± 1.1 weeks, Xeomin 11.4 ± 1.3 weeks). The interinjection interval (II) throughout the treatment course was 14.8 ± 1.9 weeks (Botox 14.7 ± 1.6 weeks, Xeomin 15.0 ± 2.2 weeks). The mean difference between Botox and Xeomin was 0.3 weeks for TD (two-sided 95 % confidence interval [-0.3; 0.9]) and 0.5 weeks for II (two-sided 95 % confidence intervals [-0.4; 1.4]). The confidence intervals of both parameters were within the predefined therapeutic equiva-lence range set to ±1.5 weeks, thus indicating similar efficacy of both BT drugs. Having based the exchange of Botox and Xeomin on a conversion factor of 1:1 our data confirm previous findings of an identical potency labelling of both products, thus allowing comparisons of efficacy, adverse effects and costs