A double blind, randomised, parallel group study to investigatethe dose equivalence of Dysport® and Botox®in the treatment of cervical dystonia

OBJECTIVE—This study was designed toestablish whether a ratio of three units of Dysport^® isequivalent to one unit of Botox^® for the treatment ofcervical dystonia.
METHODS—Patients with predominantly rotationalcervical dystonia, and a minimum of four previous Botox treatments,were randomised to receive either the clinically indicated dose ofBotox or three times that dose in Dysport units. Study botulinum toxinwas administered in a double blind fashion, to one or more clinicallyindicated muscles, at one or more sites per muscle. Patients returnedfor assessment two, four, eight, and 12 weeks after treatment.
RESULTS—A total of 73 patients (Dysport, 38;Botox, 35) were entered. The Dysport group received a mean (SD) dose of477 (131) (range 240-720) Dysport units, and the Botox group receiveda mean (SD) dose of 152 (45) (range 70-240) Botox units. The mean(SEM) post-treatment Tsui scores for the Dysport group (4.8 (0.3)) andthe Botox group (5.0 (0.3)) were not statistically different (p=0.66).The study had 91% power to detect a clinically significant differenceof two points. Both groups showed substantial improvement in Tsui scoreby week 2 (mean (SD); Dysport, 46 (28)%; Botox, 37 (28)%), with apeak effect at week 4 (mean (SD); Dysport, 49 (29)%; Botox, 44 (28)%). A similar response profile was seen for other assessments ofefficacy. The duration of effect, assessed by time to retreatment, wasalso similar (mean (SD); Dysport, 83.9 (13.6) days; Botox, 80.7 (14.4)days; p=0.85). During the study 22 of 38 (58%) Dysport patientsreported 39 adverse events, and 24 of 35 (69%) Botox patients reported56 adverse events (p=0.35). A global assessment of efficacy and safetyconsidered that 29 of 38 (76%) Dysport patients and 23 of 35 (66%)Botox patients were treatment successes (p=0.32).
CONCLUSION—Patients with predominantly rotationalcervical dystonia treated with the clinically indicated dose of Botoxor three times that dose in Dysport units show similar improvements anddo not have significantly different safety profiles.