Alkalinized lidocaine solution as a first-line local anesthesia protocol for intradetrusor injection of onabotulinum toxin A: results from a double-blinded randomized controlled trial

Aims: Local anesthesia protocols for intradetrusor onabotulinum toxin A (BoNTA) injection lack standardization. We aimed to determine if an alkalinized lidocaine solution is more effective than lidocaine only. Methods: Patients of both genders aged 18 or above enlisted for intradetrusor BoNTA injection (idiopathic, neurogenic, and bladder pain syndrome) were included in a double-blinded randomized controlled trial after obtaining their informed consent. All participants filled a bladder diary and a urine culture was performed. Subjects were randomized 1:1 to Protocol A (20 ml 2% lidocaine + 10 ml 8.4% sodium bicarbonate) or Protocol B (20 ml 2% lidocaine + 10 ml 0.9% saline solution). A Numeric Rating Scale (0–10) was used to assess the level of pain immediately after the procedure (primary endpoint). Secondary endpoints included pain after 1 h, urinary tract infection, acute urinary retention, and hematuria related to the procedure. Results: A total of 116 patients were randomized. Baseline characteristics (age, sex, indication, and bladder diary parameters) of patients in Group A and B were similar. Pain scores at the end of the procedure were significantly lower with the alkalinized solution (Protocol A and B, respectively, 2.37 ± 0.31 vs. 4.44 ± 0.36, p <.01). No differences were observed 1 h after treatment (Protocol A and B, respectively, 0.54 ± 0.17 vs. 0.69 ± 0.19, p =.487). The only adverse event reported was mild-to-moderate self-limited hematuria in 15.4% of patients. Conclusions: The use of an alkalinized lidocaine solution has proven to be significantly superior to lidocaine only as local anesthesia before intradetrusor BoNTA injection, suggesting that this may be considered a first-line option.