Alkalinised lidocaine as an anaesthetic before onabotulinumtoxinA injections. a randomised trial

To evaluate the effect of intravesical alkalinised lidocaine as an anaesthetic treatment on procedural pain during intradetrusor onabotulinumtoxinA (BTX-A) injections for overactive bladder.

This single-centre, randomised, double-blind, placebo-controlled two period crossover trial was conducted on women scheduled for BTX-A injections at our outpatient urogynaecology clinic between September 2022 and May 2024. Patients were randomly assigned (1:1) to receive either alkalinised lidocaine or placebo during the first treatment period. Alkalinised lidocaine solution comprised lidocaine hydrochloride (20 mg/mL, 20 mL), sodium hydrogen carbonate (1 mmoL/mL, 10 mL), and sodium chloride (9 g/L, 10 mL). The matching placebo was sodium chloride (9 g/L, 40 mL). The primary outcome measure was procedural pain rated on a 100-mm visual analogue scale (VAS). Secondary outcomes included adverse effects such as post-void residual urine volumes requiring catheterisation, urinary tract infection, haematuria 1 week after treatment, and patient satisfaction measured on a 5-point scale. During the second treatment period, patients received the alternative intervention.

We enrolled 50 patients, of which 41 were eligible for per-protocol analyses. The mean VAS score was significantly lower following intravesical alkalinised lidocaine (mean 21.3 mm, 95% confidence interval [CI] 14.7-27.8 mm) compared to placebo (mean 41.6 mm, 95% CI 35.0-48.1 mm) with a mean difference of -20.3 mm (95% CI -29.2 to -11.5 mm; P < 0.001). Adverse events and patient satisfaction did not significantly differ between the alkalinised lidocaine and placebo treatments (P = 0.825 and P = 0.138, respectively).

Intravesical instillation of alkalinised lidocaine before BTX-A injections significantly reduced VAS pain scores compared to placebo (ClinicalTrials.gov identifier: NCT05415865).