Intravesical instillation of botulinum toxin A: an in vivo murine study and pilot clinical trial

AIM: The objectives of this study were to compare the urodynamic effects of botulinum toxin A (BoNT-A) delivered via intramural injection into the bladder wall to that of intravesical instillation in a rat model of detrusor overactivity and to evaluate the effects of intravesical instillation of BoNT-A in female patients with idiopathic overactive bladder.

MATERIALS AND METHODS: Detrusor overactivity was induced in female Wistar rats using partial bladder outflow obstruction. Animals were treated with 5 units (U) of BoNT-A via intramural bladder injection (n = 6) or intravesical instillation (n = 7). Conscious cystometrograms were performed prior to BoNT-A administration and then repeated 7 days and 2 weeks following treatment. In the subsequent pilot clinical study, 16 female patients with overactive bladder refractory to antimuscarinics were treated with 200 units of BoNT-A in 50 mL of 0.9% saline instilled using a 12-F urethral catheter. Treatment outcome was evaluated immediately prior to and 1 month after BoNT-A administration.

RESULTS: In the preclinical study, the average intermicturition and threshold pressures, as well as the number and amplitude of non-voiding bladder contractions, decreased significantly in both instillation and injection groups. Micturition pressure decreased significantly only in the intramural injection group. In the pilot clinical study, seven patients reported improvement in symptoms. The average number of incontinence episodes was significantly reduced, and the volume at which the first non-voiding contraction was recorded increased by 52.8%.

CONCLUSION: The results of our urodynamic studies support the hypothesis that BoNT-A instilled into the urinary bladder affects bladder sensation.