OnabotulinumtoxinA intradetrusor injections effectively treat overactive bladder and urgency incontinence in individuals who have not responded to or are intolerant of anticholinergics. Less frequent intradetrusor injections might be avoided if onabotulinumtoxinA were administered by instillation instead.
The study’s investigators hoped to determine how well an onabotulinumtoxinA + hydrogel combination would work and whether it would be safe to inject it into the urethra. Participants were selected for Stage 2 and randomly assigned to receive either 100, 300, 400, or 500 U of onabotulinumtoxinA with hydrogel admixture or a placebo after an independent committee reviewed Stage 1 for safety. The primary end point was the percentage of participants who experienced a more than or equal to 50% decrease in urinary incontinence episodes per day from baseline to week 12.
Secondary endpoints included the number of micturition, urgency urinary, and nocturia episodes per day, the volume voided per micturition and the proportion of participants who experienced a 50% or greater decrease in urinary incontinence episodes per day. There were recorded adverse events. The number of urine incontinence episodes decreased from baseline to week 12 by a mean of -2.72 for the placebo group and by a range of -0.89 to -1.85 for the onabotulinumtoxinA + hydrogel treatment groups. No efficacy endpoint was found to be significantly different from the placebo. Asymptomatic bacteriuria had the greatest reported incidence rate (6.7%-15.5%) among treatment-emergent adverse events, but the incidence rate was similar across all groups.
Urinary retention or an abnormally high residual volume after urination were not reported. OnabotulinumtoxinA + hydrogel admixture was well tolerated but did not outperform placebo when used for the treatment of refractory overactive bladder.