Intravesical resiniferatoxin for the treatment of hypersensitive disorder: a randomized placebo controlled study

Present therapeutic approaches to control hypersensitive disorder of the lower urinary tract and bladder pain are clinically and scientifically unsatisfactory. We performed a randomized placebo controlled study with followup after 1 and 3 months using intravesical resiniferatoxin to treat hypersensitive disorder and bladder pain.

We prospectively randomized 18 patients into 2 groups to receive a single dose of 10 nM. resiniferatoxin intravesically (group 1) or a placebo saline solution only (group 2). All patients had at least a 6-month history of frequency, nocturia, urgency and symptoms of pelvic pain as well as no urinary tract infection within the last 3 months, functional disorders of the lower urinary tract, or other vesical or urethral pathology. Pretreatment voiding pattern and pain score were recorded. Patients were evaluated after 30 days (primary end point) and 3 months (secondary end point).

The 2 groups were adequately homogeneous in regard to patient age, sex ratio, disease duration, voiding pattern and pain score. At the primary end point mean frequency plus or minus standard error of mean was decreased from 12. 444 +/- 0.70 voids to 7.111 +/- 0.67 and nocturia from 3.777 +/- 0. 27 to 1.666 +/- 0.16 (p <0.01). We observed a lesser significant improvement in mean frequency in group 1 at the secondary end point to 10.444 +/- 0.94 voids (p <0.05). No significant modification was noted in patients assigned to placebo. Mean pain score significantly decreased in group 1 at the primary end point from 5.555 +/- 0.29 to 2.666 +/- 0.23 (p <0.01) but not at the secondary end point (4.777 +/- 0.66, p >0.05). No statistically significant improvement in mean pain score was observed in placebo group 2. During resiniferatoxin infusion 4 group 1 patients noticed a light warm or burning sensation at the suprapubic and/or urethral level.

Intravesical resiniferatoxin may significantly improve the voiding pattern and pain score in patients with hypersensitive disorder and bladder pain. Because resiniferatoxin did not cause a significant warm or burning sensation at the suprapubic and/or urethral level, it may be considered a new strategy for treating hypersensitive disorder and bladder pain. However, further studies are necessary to confirm our results and define the resiniferatoxin mechanism of action, dose and necessary treatment schedule.