Botulinum toxin A (Botox, Dysport) appears to be beneficial for the treatment of patients with idiopathic overactive bladder that is not adequately managed by anticholinergic drug therapy, according to a double-blind, placebo-controlled study presented at the European Association of Urology annual congress in Barcelona, Spain.

"The benefit/risk ratio has been evaluated over a broad range of [botulinum toxin A] doses in the idiopathic OAB population, and doses of 100 U to 150 U provide the appropriate benefit/risk balance," said Chris Chapple, MD, of Royal Hallamshire Hospital, Sheffield, United Kingdom. "The clinically meaningful benefit is balanced with dose-dependant post-void residual urine volume elevation."

Patients in the study were randomized to receive either botulinum toxin A at a dose of 50 U, 100 U, 150 U, 200 U, or 300 U; or placebo. Botulinum toxin was administered as intradetrusor injections. Patients were followed for 36 weeks after treatment with assessments that included a 7-day bladder diary, post-void residual urine volume, health-related quality of life questionnaires, and urodynamics.

"We were happy to see durable and clinically meaningful efficacy for all Botox dose groups of 100 U and above with significant reductions from baseline compared to placebo in patient symptoms, including being incontinence-free," Dr. Chapple said.

Dose response was identified in efficacy parameters. However, an urge urinary incontinence analysis demonstrated minimal additional efficacy at doses above 150 U, and several health-related quality-of-life measures showed minimal incremental benefit above 100 U, Dr. Chapple said.

Look for more coverage from the EAU annual congress in the June issue of 