Treatment of overactive bladder with botulinum toxin type B: a pilot study.

The purpose of this study was to determine the efficacy and safety of botulinum toxin type B (BTX-B/Myobloc) in the treatment of patients with overactive bladder. This open-label dose-escalation study enrolled 15 female patients with urinary frequency with or without incontinence. The BTX-B doses used in this study were 2500, 3750, 5000, 10 000 and 15 000 units. Response was defined as a subjective improvement in frequency, urgency and incontinence symptoms. A paired t-test of the pre/post frequency difference indicates that these 15 patients experienced an average of 5.27 fewer frequency episodes per day after treatment with BTX-B. The p value for the paired t-test was <0.001. The longest duration effect was 3 months using 10 000-15 000 units of BTX-B. The correlation between dose and duration was very significant, with a correlation coefficient = 0.96, p<0.001. Based on these findings, we feel the use of botulinum toxin to treat patients with overactive bladder warrants further study.