The Food and Drug Administration said Friday it has approved Allergan's Botox injection for a new use in treating patients with overactive bladder that does not respond to conventional medications.
Patients with overactive bladder experience frequent, unexpected contractions of the bladder, which causes an urgent need to urinate. About 33 million people in the U.S. have the problem, according to the FDA. The condition is typically treated with nervous system-acting drugs called anticholinergics, though they do not work for all patients.
A Botox injection treats the problem by relaxing the bladder muscles and allowing more space for urine storage.
In company trials, patients injected with Botox had 1.6 to 1.9 fewer urinary leakage problems per day than patients taking a placebo.
Botox is already approved for a half-dozen uses, most famously for removing wrinkles on the forehead, but also muscle spasms, migraine and eyelid twitching. The drug was previously approved in 2011 for urinary incontinence caused by spinal cord injury or multiple sclerosis.
Botox works by blocking the connections between nerves and muscle, temporarily paralyzing the muscle. The drug is a purified form of botulinum, one of the most toxic substances in the world.
Allergan Inc., based in Irvine, Calif., reported global sales of $1.6 billion for Botox in 2011.