The US Food and Drug Administration approved Allergan's Botox for treating detrusor overactivity associated with a neurological condition such as multiple sclerosis or spinal cord injury.
The drug received a similar approval in Europe earlier this month. Patients must first have tried to control the condition with anticholinergics.
A single injection of Botox (onabotulinumtoxin A) into the bladder can relax it and increase its storage capacity, with the effect lasting for about nine months.
In two phase III trials, the most frequently reported adverse reactions within 12 weeks of treatment for detrusor overactivity due to a neurological condition included urinary tract infection (24%), urinary retention (17%), hematuria (4%), fatigue (4%), and insomnia (2%).
About 60% to 80% of patients with multiple sclerosis or spinal cord injury experience some form of bladder problems, Allergan said, out of 350,000 such patients in the United States.
Botox' active ingredient is a toxin that blocks nerve signals. It gets about half its annual sales of $1.5 billion from reducing wrinkles. It is also approved to prevent migraine headaches and to treat upper limb spasticity, neck pain from cervical dystonia and certain types of eye muscle problems and spasms of the eyelids.
Allergan also hopes to gain approval to market Botox to a broader population of patients with overactive bladder, the company's CEO David Pyott said.
(Reuters Health, Anna Yukhananov and Bill Berkrot, August 2011)