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27-03-2012 | Gynaecology | Article

Botulin injection improves bladder control in incontinent women


Free abstract

MedWire News: Women who suffer from an overactive bladder may benefit from an injection of botulinum toxin into the walls of their bladders, show findings from a UK study.

"Patients were able to pass water one or two times less often during the day, and also noticed far fewer times when they had bad feelings of urgency and had to rush to the bathroom," said lead author Douglas Tincello (University of Leicester) in a press statement.

An overactive bladder is usually caused by involuntary contractions of a bladder muscle called the detrusor muscle, explain Tincello and team. This is called detrusor overactivity (DO) and causes symptoms such as an urgent and frequent need to urinate, nocturia, and incontinence.

Currently, the condition is treated with anticholinergic drugs, which have moderate efficacy, but cause side effects such as a dry mouth, constipation, and blurred vision, and often result in patients discontinuing treatment.

However, emerging data suggest that botulinum toxin is an effective treatment for DO, write Tincello et al in European Urology. "But large studies confirming its efficacy and safety are lacking," they add.

To investigate, the team conducted a double-blind, placebo-controlled, randomized trial including 240 women with overactive bladder symptoms and DO, which had failed to improve after 8 weeks of anticholinergic therapy.

The women were randomly assigned to receive an injection of either 200-IU onabotulinumtoxinA (onaBoNTA; n=122) or placebo (n=118) into their bladder walls.

The researchers then followed up the women for 24-hour urinary voiding frequency, incontinence episode frequency, and urgency episode frequency, at 6 months post-treatment.

The authors report that the primary outcome of the median voiding frequency per 24 hours was significantly lower among the women who had received the onaBoNTA injection than it was in those who received placebo, at 8.33 versus 9.67. Similarly, median urgency episodes per 24 hours and leakage episodes per 24 hours were significantly reduced with onaBoNTA treatment when compared with placebo, at 3.83 versus 6.33, and 1.67 versus 6.00, respectively.

Furthermore, almost a third (31.3%) of the women treated with onaBoNTA achieved continence compared with only 12.0% of those treated with placebo, a significant between-group difference.

On the other hand, the team found that urinary tract infection occurred in a significantly greater proportion of those treated with onaBoNTA compared with placebo, at 31% versus 11%. And a significantly greater proportion of the onaBoNTA versus placebo group also experienced difficulty voiding that required self-catheterization, at 16% versus 4%.

"These findings are important because many doctors have been offering this treatment to patients based on the information from previous studies in people with spinal injuries, and now we have accurate information on exactly what benefit is likely to be noticed after treatment and how common the side effects will be," said Tincello. "This will allow patients to decide whether they wish to have this treatment, which at the moment is not licensed for treating DO and [overactive bladder]."

He added: "Since the effect of the treatment is so much greater than a six month course of tablets, our work may lead to botulinum toxin being used much more widely for this bladder condition and it may even turn out to be cheaper too."

By Sally Robertson

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