The Food and Drug Administration has approved Botox (onabotulinumtoxin A) for treatment of urinary incontinence that is the result of a neurologic condition, such as multiple sclerosis or a spinal cord injury, in adults who have not responded to or who cannot tolerate anticholinergic medications. Currently, the FDA approval does not extend to other causes of urinary incontinence.
Botox is the trade name for botulinum toxin, a protein produced by the bacterium Clostridium botulinum, and the most potent neurotoxin discovered thus far. The most popular uses for Botox include relaxing facial wrinkles, although it has also been approved to treat excessive sweating, chronic migraines, and other conditions.
The newest approval was partly based on the success seen in two placebo-controlled Phase III clinical studies involving 691 patients with urinary incontinence related to multiple sclerosis or spinal cord injuries. In both studies, patients who received Botox experienced a significant reduction in the frequency of incontinence episodes when compared with patients who received placebo.
The treatment involves injecting Botox into the bladder, which causes the bladder to relax and to increase its storage capacity. Doctors inject Botox with the assistance of a cystoscope, which allows them to see the interior of the bladder before they make the injection. In the phase III trials, 30 injections of 1 mL each were made into the bladder, evenly distributed into the bladder detrusor. The Botox injection is effective in reducing urinary incontinence for up to 10 months before retreatment is necessary.
Botox injections are not without side effects. The most common adverse reactions reported following initial injection were urinary tract infections (49%), urinary retention (17%), fatigue (6%), constipation (4%), and muscle weakness (4%).
Center for Drug Evaluation and Research. Approval package for Botox. 2011 Aug 24