Efficacy and safety of a new bulk toxin of botulinum toxin in cervical dystonia: a blinded evaluation.

We investigated the efficacy and safety of botulinum toxin A (BTX) manufactured from a new bulk strain for the treatment of cervical dystonia. This was a single-blinded retrospective comparison of length of benefit, subjective improvement, and complications of treatment in 50 patients treated with the old form of toxin designated 79-11 and the new toxin strain BCB2024. The mean duration of benefit of the 79-11 strain and the BCB2024 strain were the same. Subjective efficacy, measured on a -4 to +4 scale, demonstrated no difference between the two strains. Dysphagia occurred in 12% of patients injected with the 79-11 strain and 14% of subjects injected with the BCB2024 strain. We also used a clinician's global assessment that incorporated the duration of benefit, subjective efficacy, and complications as a secondary analysis. There was no significant difference between the two forms of botulinum toxin A according to this scale. We conclude that the 79-11 strain and the BCB2024 strain offer similar peak efficacy duration of benefit, and adverse events.