Intravesical instillation of onabotulinum toxin A embedded in inert hydrogel in the treatment of idiopathic overactive bladder: A double-blind randomized pilot study.

Objective: It was hypothesized that increasing the time for which onabotulinum toxin A (OnabotA) is exposed to the urothelium following intravesical instillation will augment its effect. TC-3 is an inert heat-sensitive hydrogel, which creates an intravesical bulk providing a slow release of the embedded drug after instillation. The aim of this study was to evaluate the effect of OnabotA, embedded in inert TC-3 hydrogel, in patients with idiopathic overactive bladder (OAB).

Methods: In total, 39 female patients (age 30-65, average 53.8 years) with OAB symptoms were randomized for the study into four groups, each receiving 50 ml of the following intravesical instillations: Group A, 0.9% NaCl (placebo, n = 11); Group B, TC-3 gel + 200 U OnabotA (n = 9); Group C, TC-3 gel + 200 U OnabotA + dimethyl sulfoxide (DMSO) (n = 10); and Group D, DMSO (n = 9). The parameters were compared before and 1 month after treatment.

Results: When comparing parameters using conventional statistical methods (Kruskal-Wallis test), no statistically significant changes were observed within the groups. Comparison of the medians using an analysis based on the mathematical gnostics showed the superiority of the method used in Group B over the other groups in the following parameters: number of urgency grade 3 + 4 episodes/72 h, number of leakage episodes/72 h, Overactive Bladder Questionnaire total score and Patient Perception of Bladder Condition total score. Group D showed its superiority over the other groups in respect to the number of nocturia episodes/72 h.

Conclusions: The results indicate that intravesical instillation of OnabotA, embedded in TC-3 gel, could become an alternative to intramural injection for a well-selected subgroup of patients.