Assessing the Effectiveness of “Onabotulinumtoxin A”(Botox®) Intradetrusor Injection for Overactive Bladder(OAB) Patients After Medical Therapy Failure

Background: Urge urinary incontinence (UUI) is a persistent and disabling condition that occurs in Overactive Bladder (OAB) patients without evidence of urinary tract infection (UTI). At our institution, intradetrusor injections of onabotulinumtoxinA (BTX-A) are implemented as a second-line therapy for patients in whom pharmacological management has failed. Methods: Between January 2020 and March 2023, 62 patients (38 women, 24 men) with prior treatment using antimuscarinic agents and/or β3-adrenoceptor agonists were evaluated. Of these, 14 had significant comorbidities, including 8 patients with neurological disorders. Those with neurological involvement received 200 U of onabotulinumtoxinA, whereas the remaining 54 received 100 U (Botox®, Allergan, Irvine, CA, USA). Follow-up assessments at 3, 6, 12 and 24 months included urinary leakage (Pad test), the need for clean intermittent catheterisation (CIC), completion of the OAB questionnaire and monitoring of adverse events. Results: The treatment resulted in significant reductions in urinary leakage (UL) at 3 and 6 months compared with baseline, along with a marked decrease in detrusor pressure at 6 months (p < 0.05). Both the 100 U and 200 U regimens maintained clinical efficacy for up to one year postprocedure. The incidence of adverse events was comparable to that observed with oral pharmacotherapy. Conclusions: Intradetrusor BTX-A is a safe and effective therapeutic option for OAB patients who are unresponsive to other therapeutic options. The major benefits observed were lowered detrusor pressure and reduced UL at 6 months, as well as reduced CIC at 6 and 12 months. A 100 U dose appears adequate for most cases, although its benefit tends to diminish after 12 months. Thus, we propose to repeat the procedure after about one year. However, no clinically relevant differences were observed between the 100 U and 200 U doses.