Treatment of Overactive Bladder with Botulinum Toxin: Are There More Challenges to Deal With?

Abstract

Bladder wall injections with botulinum neurotoxin type A (BoNTA) have emerged as an official second-line treatment for intractable incontinence due to neurogenic detrusor overactivity (DO), but it remains an unlicensed treatment for intractable urinary symptoms associated with idiopathic detrusor overactivity (IDO)/overactive bladder (OAB) despite increasing acceptance and use under local institution approvals worldwide. Although the efficacy of BoNTA intradetrusor injections in patients with OAB/IDO has been established in several randomized controlled and openlabel studies, mainly using the onabotulinumtoxinA (Botox) format [1], the risk–benefit ratio of the treatment remains a major issue. Analysis of clinical and urodynamic results of a single large dose-ranging trial identified a plateau of efficacy at doses of onabotulinumtoxinA >150 U [2,3]; the 100-U dose was the minimum dose to achieve a durable efficacy. Respective data on the abobotulinumtoxinA (Dysport) format derive from small noncontrolled studies and cannot be considered definitive. In addition, safety concerns associated largely with the risk of increased postvoid residuals (PVRs) and/or the need for clean intermittent catheterizations (CICs) following treatment have yet to be addressed. The specific effect of using (or having to use) CICs on quality of life (QoL) and well-being of patients with IDO, surprisingly, has been little studied. In most reports it has been masked under the vast overall improvement in patients’ QoL related to the reduction in urgency and associated incontinence [4]. However, other studies have suggested patients’ reservations regarding the treatment and its side effects [5]; only about half the women with OAB, independent of the response to first-line therapy with anticholinergics, considered intradetrusor BoNTA an acceptable treatment for their symptoms when taking into account both outcomes and possible complications. CIC-related issues were the second most common cause for treatment discontinuation when repeat injection data were analyzed [6].