The median duration for efficacy with BOTOX® at reducing urinary leakage and other symptoms of OAB in the two clinical studies was 135-168 days compared to 88-92 days with placebo based on qualification for retreatment. To qualify for retreatment, at least 12 weeks must have passed since the prior treatment, post-void residual urine volume must have been less than 200 mL and patients must have reported at least two urinary incontinence episodes over three days. BOTOX® treatment relieves OAB symptoms by temporarily calming muscle contractions by blocking the transmission of nerve impulses to the bladder muscle.OAB Clinical Development ProgramThe FDA approval of BOTOX® was based on safety and efficacy data from two double-blind, randomized, multi-center, placebo-controlled 24-week clinical studies of 1,105 adult patients whose OAB symptoms had not been adequately managed with anticholinergic therapy, either due to lack of efficacy or intolerance of the medication. To qualify for the study, patients had to have symptoms of OAB with symptoms of urge urinary incontinence, urgency and frequency, and experience a minimum of three urinary urgency leakage (incontinence) episodes and at least 24 urination episodes (micturitions) over a three-day timeframe. Patients in the studies were randomized to receive physician-administered treatment with 100 units of BOTOX® neurotoxin (n=557) or placebo (n=548) injected directly into the detrusor (bladder) muscle. Patients were treated in the physician’s office and received a local anesthetic, with or without sedation, to numb the bladder prior to treatment with BOTOX® or placebo. In both clinical trials, patients treated with BOTOX® experienced a reduction of 50% or more in the frequency of daily urinary incontinence episodes from baseline compared to placebo at week 12 (reduction of 2.5 episodes from baseline of 5.5 episodes in one study and reduction of 3 episodes from baseline of 5.5 episodes in the second study for those treated with BOTOX® vs. a reduction of 0.9 episodes from a baseline of 5.1 episodes in one study and a reduction of 1.1 episodes from a baseline of 5.7 episodes in the second study for those treated with placebo). 1 In addition, approximately three times as many patients treated with BOTOX® in the clinical studies achieved a complete elimination of their leakage episodes as compared to placebo (22.9% and 31.4% achieved complete continence with BOTOX® vs. 6.5% and 10.3% with placebo at week 12 in the two clinical trials). 5 Improvements in other symptoms of overactive bladder, including urge to urinate, frequency of urination and the amount of urine voided also occurred with BOTOX® treatment compared to placebo at week 12. In the clinical studies, the most frequently reported adverse reactions within 12 weeks of receiving BOTOX® injections included urinary tract infection (18% vs. 6% with placebo), dysuria (9% vs. 7% with placebo), which means painful or difficult urination; and urinary retention (6.5% vs. 0.4% with placebo), which is a temporary inability to fully empty the bladder requiring the use of a disposable self-catheter.