Overactive bladder treatment: application of methylene blue to improve the injection technique of onabotulinum toxin A.

[OBJECTIVE] The aim of this study was to test the addition of methylene blue (MB) to onabotulinum toxin A (BTX-A) solution in overactive bladder (OAB) treatment, as a means of facilitating observation of the injection site and assessing the distribution of the drug under the bladder mucosa during injection. Pharmacological interactions between BTX-A and MB were also evaluated.

[MATERIALS AND METHODS] The study was conducted between December 2014 and April 2016 on 30 patients: six males and 24 females (median age 57.7, range 23-80 years) diagnosed with OAB, who qualified for intravesical BTX-A injection. Each received 100 IU of BTX-A (Botox; Allergan), dissolved in 9.5 ml of 0.9% NaCl with the addition of 0.5 ml of MB. Cystoscopy with submucosal injection of the solution was performed systematically, including the bladder triangle. For pharmacological evaluation, quantitative determination of MB was performed on a capillary electrophoresis system with diode array detection.

[RESULTS] In the course of 600 injections, the addition of MB facilitated the observation of the procedure; the exact distribution of the solution could not be observed in only 43 injections in seven patients. The range of distribution of the drug varied from 1 to 2.5 cm. Pharmacological evaluation based on visual observations and experiments showed that pharmaceutical interactions do not occur between MB and this commercially available formulation of BTX-A.

[CONCLUSIONS] Applying a coloured solution of BTX-A significantly facilitates observation of the procedure and assessment of drug distribution. There are no pharmaceutical interactions between MB and BTX-A.