Resiniferatoxin is an extract extracted from the Euphorobia plant and it contains, in its molecular structure, the homovanilil group, which, probably,  is the reason that it activates a specific place in the cellular membrane of the sensorial neurons of type C, known as vanilil receptor 1,2. Clinical evidence and experiments have suggested the involvement of afferent fibers of type C in hyperreflexy and in vesical instability 3.
This substance is a potent vanilla with a desensitizing effect in nanomolar concentration. On the case of the bladder, it occurs in low doses like 10nM. Meanwhile, the desensitizing and dependent dosage, and studies have shown that doses of 10nM,  in patients  with an instable bladder, gives a beneficial effect during weeks, as doses above 50nM, cause clinical and urodynamic alterations for several months 4.
Even though recent initial studies using resiniferotoxin, showed that this substance may desensitize vesical sensorial fibers and treat patients with detrusor instability, without evoking significant adverse effects, local anesthesia is not necessary for this procedure. The results have shown to be lasting and positive, after one only intravesical instillation of the medicine, reducing episodes of urinary loss frequency and enlarging vesicle capacity 5,6.
The authors describe their experience with this substance in a group of patients carriers of detrusor instability refractory to the use of anticholinergic.