Lidocaine is a common local anesthetic and antiarrhythmic drug that acts via the local anesthetic effect of blocking voltage-gated sodium channels in peripheral neurons. To evaluate lidocaine as a therapeutic agent, we investigated optimal concentrations and effects of intravesical lidocaine instillation in a bladder outlet obstruction (BOO)-induced rat model of overactive bladder (OAB).
To determine the therapeutic dosage of lidocaine, 16 female Sprague-Dawley (SD) rats (mean weight = 200 ± 20 g) were divided into four treatment groups: those receiving saline, 0.5% lidocaine, 1% lidocaine, and 2% lidocaine (n = 4 per group). Twenty-four additional SD rats were divided into two groups to investigate the effect of 1% lidocaine treatment in rats with BOO and normal rats (n = 12 per group). Cystometry was performed by infusing physiological saline and lidocaine into the bladder at a slow infusion rate (0.04 mL/min). Cystometric parameters were analyzed using PowerLab®. The expression of c-Fos, a protein expressed by C-fibers in the spinal cord (L6), was investigated via western blotting.
Among the test lidocaine doses, only 1% lidocaine increased the intercontraction interval (ICI) (control mean = 500.56 ± 24.4 s; treatment mean = 641.0 ± 49.3 s; p < .01) without changes in threshold pressure and basal pressure. In the BOO-induced OAB group, the ICI increased significantly after instillation of 1% lidocaine (control mean = 135.8 ± 12.87 s; OAB-group mean = 274.2 ± 33.21 s; p < .01). Detrusor overactivity and non-voiding contraction were observed in the control group but not in rats with BOO after lidocaine instillation. The expression of c-Fos in C-fibers in the spinal cord (L6) decreased significantly after 1% lidocaine treatment in rats with BOO.
Intravesical instillation of 1% lidocaine improves cystometric parameters without deterioration of contractility by blocking excessive C-fiber activity in the rat model of BOO-induced OAB. Therefore, instillation of 1% lidocaine has minimal effects on normal nerves while blocking nerves that contribute to OAB. Our findings suggest that intravesical instillation of 1% lidocaine is a useful treatment for OAB.
Urology journal. 2019 Oct 20 [Epub ahead of print]
Hyo Jin Kang, Sang Woon Kim, Yong Seung Lee, Sang Won Han, Jang Hwan Kim
Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea. ., Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.