The FDA has expanded the approved use of Allergan Inc’s Botox (onabotulinumtoxinA) to treat adults with overactive bladder (OAB) who cannot use or do not adequately respond to a class of medications known as anticholinergics.
Affecting about 33 million men and women in the United States, OAB is a condition in which the bladder squeezes too often or squeezes without warning. Symptoms include leaking urine (urinary incontinence), feeling the sudden and urgent need to urinate, and frequent urination.
When Botox is injected into the bladder muscle, it causes the bladder to relax, increasing the bladder’s storage capacity and reducing episodes of urinary incontinence. Injecting the bladder with Botox is performed using cystoscopy, a procedure that allows a doctor to visualize the interior of the bladder while Botox is being injected.
Botox may help refractory OAB patients, says Victor Nitti, MD, the vice-chairman of urology and professor of urology at NYU Langone Medical Center in New York City. He also served as an investigator in the trial that led to this approval. “They are the OAB patients who have failed to respond to medical therapy including anticholinergic agents or who have been unable to tolerate those same medications,” he tells PSP. These patients include both men and women.
Studies suggest the effects can last up to 6 months. To treat OAB, urologists typically make about 20 injections throughout the bladder to cover a large percentage of its surface area. “We deliver the Botox to the majority of the bladder muscle so it has a global effect,” he says.
The shots are not particularity painful, Nitti says. “It is done in an office setting, most commonly with local anesthesia,” he says. Once the anesthetic begins to work, the divot will insert the cystoscope.
Some insurers already cover the cost of the treatment for OAB, but the new FDA approval will likely encourage more to follow suit.
Importantly, Nitti says, the new indication does not apply to Botox alternatives. These other products have not been widely studied in the lower urinary tract. “The toxins work in a similar manner, but one is not equivalent to another.”
Risks do exist, he says. “Theoretically, there is a risk of the toxin spreading, but we didn’t see any major side effects at a low dose used in the clinical trial,” he says.
Botox’s safety and effectiveness for this new indication were established in two clinical trials of 1,105 patients with symptoms of OAB. Patients were randomly assigned to receive injections of 100 units of Botox (20 injections of five units each) or placebo.
Results after 12 weeks showed that patients treated with Botox experienced urinary incontinence an average of 1.6 to 1.9 times less per day than patients treated with placebo. Botox-treated patients also needed to urinate on average 1.0 to 1.7 times less per day and expelled an average of about 30 milliliters more urine than those treated with placebo.
Treatment with Botox can be repeated when the benefits from the previous treatment have decreased, but there should be at least 12 weeks between treatments.
Common side effects reported during clinical trials included urinary tract infections, painful urination, and incomplete emptying of the bladder (urinary retention). Patients who develop urinary retention may need to use a catheter until the urinary retention resolves. Patients being treated for OAB with Botox should not have a urinary tract infection and should take antibiotics before, during, and for a few days after Botox treatment to lower the chance of developing an infection from the procedure.
SOURCE: FDA news release