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RESEARCH PRODUCT

OnabotulinumtoxinA: how deep will it go?

subject

description

First-line treatment of overactive bladder syndrome (OAB) is based on conservative measures and oral medication such asmuscarinic receptor antagonists and, more recently, b3-adrenoceptor agonists.While this provides effective symptom relief for many patients, for others it has insufficient efficacy and/or intolerable side effects. The potent neurotoxin onabotulinumtoxinA (BoNT-A) has shown efficacy in placebo-controlled trials in patients with neurogenic voiding dysfunction or OAB [1], largely including patients exhibiting an insufficient treatment response to muscarinic antagonists. Although the role of a strong placebo component in the beneficial effects of oral treatment is well known, a considerable placebo responsewas also seen with injection treatment, even in patients refractory to oral treatment. This placebo response accounted for about one-third to half of that for active BoNT-A treatment, depending on the outcome parameter being studied, and testifies to the power of placebo when administered by injection. Key adverse events (AEs) of BoNT-A are increases in postvoiding residual urine and a need for catheterization. Although the incidence of these AEs varies considerably between trials, it is clearly dose dependent [2]. These AEs may partly mitigate the beneficial effects of BoNT-A for quality of life and lead to additional morbidity such as urinary tract infections (UTIs). The proof-of-concept study by Kuo et al. [3] in this month’s issue of European Urology attempts to kill two birds with one stone by administering a liposomal BoNT-A preparation by intravesical installation for 60 min. First, intravesical installation may avoid the need for anesthesia with administration by injection. Second, and perhaps more important, liposomal BoNT-A maymaintain the efficacy seenwith injection but exhibit an improved AE profile.