Safety, effectiveness, and duration of effect of BOTOX after switching from Dysport for blepharospasm, cervical dystonia, and hemifacial spasm

Background: Local injection of botulinum toxin type A is first-line treatment of blepharospasm, cervical dystonia, and hemifacial spasm; however, there is uncertainty about the optimal dose of toxin for each indication as well as dose-conversion ratios that should be used when switching products in clinical practice. Objective: The goal of this study was to compare the safety, effectiveness, and duration of clinical effect of BOTOX* and Dysport dagger after drug switching (Dysport to BOTOX) among patents with movement disorders. Methods.-A total of 48 patients diagnosed with blepharospasm (n = 27), cervical dystonia (n = 12), or hemifacial spasm (n = 9) were evaluated during a single-arm, crossover-design study in which each patient was his/her own historical control using a 5:1 or 4:1 conversion ratio of Dysport to BOTOX units. Patients were assessed (using Jankovic, Visual Analog Scale, general pain scale, Toronto Western Spasmodic Tiorticollis Rating Scale [TWSTRS] scores) after the last injection of Dysport and the first injection of BOTOX. Moreover, each patient kept a diary during treatment to track onset and duration of therapeutic effect. Results: Although BOTOX and Dysport were both clinically effective, this effect was more significant with BOTOX compared to Dysport based on TWSTRS for cervical dystonia (P = 0.012), and Jankovic scores for blepharospasm (p = 0.006). Longer duration of effect also was noted with BOTOX than with Dysport (blepharospasm, 62.2 days vs 47.4 days (p = 0.001); cervical dystonia, 64.3 days vs 44.6 days (p = 0.014); hemifacial spasm, 65.1 days vs 41.8 days (p < 0.014), respectively). Of the 48 patients, 19 experienced at least one adverse drug reaction (ADR) during Dysport treatment, with the most commonly reported ADRs being ptosis for blepharospasm and hemifacial spasm and neck weakness for cervical dystonia. No patient reported an ADR during BOTOX treatment. Conclusions: Results suggest therapeutic effectiveness is enhanced with BOTOX compared to Dysport at a dosing ratio between 5:1 and 4:1 (Dysport:BOTOX). Safety and duration of therapeutic effect also are enhanced with BOTOX. Further research is needed.