Repeated treatment with onabotulinumtoxinA consistently reduces urinary incontinence (UI) episodes in patients with neurogenic detrusor overactivity, show findings from an extension study of Phase III trials.
Two recent trials showed that a single treatment with the toxin was effective at reducing such episodes for 9-10 months in patients who had UI due to spinal cord injury or multiple sclerosis and who were inadequately treated with anticholinergics.
"The present results have demonstrated that onabotulinumtoxinA is effective in the long term with repeated treatments in these patients… without the emergence of new safety signals," report Michael Kennelly (Carolinas Rehabilitation, Charlotte, North Carolina, USA) and colleagues.
A total of 387 patients who participated in either of the previous trials were enrolled in the current extension study and they received repeat treatments of the toxin at the same doses they had received in the previous trials (either 200 U or 300 U). The patients were evaluated at weeks 2, 6, and 12 after each treatment, with a focus on the results at 6 weeks after treatments 1 to 5.
As reported in Urology, the number of UI episodes per week that patients were experiencing 6 weeks after treatment was significantly and consistently lower with repeated cycles of treatment than the mean number recorded at baseline (31.2). Episodes decreased by 22.7, 23.3, 23.1, 25.3, and 31.9 after treatment cycles 1 to 5, respectively, in the 200-U dose group and by 23.8, 25.0, 23.6, 24.1, and 29.5 in the 300-U dose group.
The proportion of patients with at least a 50% reduction in UI episodes per week ranged from 73-94% across the treatment cycles, and a significant proportion were also considered "dry" (100% reduction in episodes), at a range of 36-55%.
Consistent increases from baseline in the mean volume/void at week 6 were also observed with repeated treatments, at a mean of at least 130 mL after each treatment.
Furthermore, quality of life was improved after repeated treatments. Approximately 70-90% of patients achieved scores on the Incontinence Quality of Life questionnaire that indicated improvements greater than the reported minimally important difference of 11 points.
Furthermore, repeat onabotulinumtoxinA treatments were well tolerated, and the adverse event (AE) profile remained comparable across the treatment cycles. As was the case in the preceding phase III trials, the most frequently reported AE was urinary tract infection.
The researchers point out that one limitation of the results is that they come from an interim analysis, which has only reported the safety and efficacy parameters up to the cutoff date. "Evaluations are ongoing in the long-term study and will further characterize the safety and efficacy profile of onabotulinumtoxinA in this patient population."
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