Safety and Feasibility of Intravesical Instillation of Botulinum Toxin-A in Hydrogel-based Slow-release Delivery System in Patients With Interstitial Cystitis-Bladder Pain Syndrome: A Pilot Study

Objective To assess the feasibility and the safety of a mixture instillation of TC-3 gel, a novel reverse-thermal gelation hydrogel, and botulinum toxin-A (BTX-A) for the treatment of interstitial cystitis-bladder pain syndrome (IC/BPS). TC-3 gel-BTX-A mix is instilled into the bladder as liquid, solidifies because of body heat, and gradually dissolves to release BTX-A for several hours. Methods A single intravesical instillation of 200 U BTX-A premixed with 40 mL TC-3 gel was delivered to the bladder. Adverse events and preliminary efficacy outcome measures were assessed: bladder diary, visual analog scale (VAS) for pain, and Interstitial Cystitis Symptom Index (ICSI) and Interstitial Cystitis Problem Index (ICPI) at baseline and at 2, 6, and 12 weeks. Results A total of 15 severely symptomatic patients with IC/BPS (ICSI and ICPI score ranges 12-19 and 12-16, respectively; median VAS = 7) were enrolled (male and female = 4 and 11, ages 24-76). In terms of safety, no increase in VAS score was noted at instillation. All adverse events were transient and mild, the most common being temporary mild constipation (n = 4, 26%). The mean VAS at baseline vs week 12 was 6.6 ± 2.7 vs 5.3 ± 2.8 ( P  = .044). The mean ICSI and ICPI scores were reduced at week 12 compared with baseline (15.4 ± 2.4 vs 12.9 ± 4.3, P  = .004, and 14.8 ± 1.4 vs 11.9 ± 4.0, P  = .004, respectively). The mean number of voids per night at baseline decreased for 6 weeks (3.3 ± 2.1 vs 1.8 ± 0.9, P  = .046) and then returned to baseline level at week 12. Conclusion Intravesical instillation of a TC-3 gel-BTX-A mixture is safe and tolerable. Preliminary results suggest temporary efficacy lasting for a few weeks.